阅读说明：本技术 层叠型全固体二次电池及其制造方法 (Laminated all-solid-state secondary battery and method for manufacturing same ) 是由 田中一正 室井雅之 于 2020-03-12 设计创作，主要内容包括：本发明提供层叠型全固体二次电池,其包括：由正极(30、330)和负极(40、340)隔着固体电解质层(50、350)层叠而成的层叠体,所述正极(30、330)具有正极集电体层(31、331)和正极活性物质层(32、332),所述负极(40、340)具有负极集电体层(41、341)和负极活性物质层(42、342),所述层叠体具有形成为与层叠方向平行的面的侧面,所述侧面包括正极集电体层(31、331)露出的第一侧面(21、121、321)和负极集电体层(41、341)露出的第二侧面(22、122、322)；设置于所述第一侧面(21、121、321)的正极外部电极(60、61、62、63、64、365)；和设置于所述第二侧面(22、122、322)的负极外部电极(70、71、72、73、74、375),所述正极外部电极(60、61、62、63、64、365)与所述正极集电体层(31、331)电连接,且所述正极外部电极(60、61、62、63、64、365)的侧端部位于不与所述负极(40、340)对置的位置,所述负极外部电极(70、71、72、73、74、375)与所述负极集电体层(41、341)电连接,且所述负极外部电极(70、71、72、73、74、375)的侧端部位于不与所述正极(30、330)对置的位置。(The present invention provides a laminated all-solid secondary battery including: a laminate formed by laminating a positive electrode (30, 330) and a negative electrode (40, 340) with a solid electrolyte layer (50, 350) therebetween, wherein the positive electrode (30, 330) has a positive electrode collector layer (31, 331) and a positive electrode active material layer (32, 332), the negative electrode (40, 340) has a negative electrode collector layer (41, 341) and a negative electrode active material layer (42, 342), the laminate has a side surface formed as a surface parallel to the lamination direction, and the side surface includes a first side surface (21, 121, 321) where the positive electrode collector layer (31, 331) is exposed and a second side surface (22, 122, 322) where the negative electrode collector layer (41, 341) is exposed; a positive external electrode (60, 61, 62, 63, 64, 365) provided on the first side surface (21, 121, 321); and a negative electrode external electrode (70, 71, 72, 73, 74, 375) provided on the second side surface (22, 122, 322), wherein the positive electrode external electrode (60, 61, 62, 63, 64, 365) is electrically connected to the positive electrode current collector layer (31, 331), and a side end portion of the positive electrode external electrode (60, 61, 62, 63, 64, 365) is located at a position not opposed to the negative electrode (40, 340), the negative electrode external electrode (70, 71, 72, 73, 74, 375) is electrically connected to the negative electrode current collector layer (41, 341), and a side end portion of the negative electrode external electrode (70, 71, 72, 73, 74, 375) is located at a position not opposed to the positive electrode (30, 330).)

1. A stacked all-solid secondary battery characterized by comprising:

a laminate in which a positive electrode having a positive electrode collector layer and a positive electrode active material layer and a negative electrode having a negative electrode collector layer and a negative electrode active material layer are laminated with a solid electrolyte layer interposed therebetween, the laminate having a side surface formed as a plane parallel to the lamination direction, the side surface including a first side surface on which the positive electrode collector layer is exposed and a second side surface on which the negative electrode collector layer is exposed;

a positive external electrode disposed on the first side surface; and

a negative external electrode disposed on the second side surface,

the positive electrode external electrode is electrically connected to the positive electrode current collector layer, and a side end portion of the positive electrode external electrode is located at a position not facing the negative electrode, and the negative electrode external electrode is electrically connected to the negative electrode current collector layer, and a side end portion of the negative electrode external electrode is located at a position not facing the positive electrode.

2. The laminated all-solid secondary battery according to claim 1, wherein:

the laminated body has an upper surface and a lower surface formed as planes orthogonal to the laminating direction,

the positive electrode external electrode and the negative electrode external electrode each have a sub-electrode extending to at least one of the upper surface and the lower surface.

3. The laminated all-solid secondary battery according to claim 2, wherein:

the tip end portion of the sub-electrode of the positive electrode external electrode is located at a position not opposed to the main surface of the negative electrode laminated at a position closest to the sub-electrode in the lamination direction.

4. The laminated all-solid secondary battery according to claim 2, wherein:

the tip end portion of the sub-electrode of the negative external electrode is located at a position not opposed to the main surface of the positive electrode laminated at a position closest to the sub-electrode in the laminating direction.

5. The stacked all-solid secondary battery according to any one of claims 1 to 4, wherein:

the first side and the second side are located at opposing positions.

6. The laminated all-solid secondary battery according to claim 1, wherein:

the side surface sub-electrode of the positive electrode external electrode is located at a position not facing the side end portion of the negative electrode, the negative electrode external electrode is electrically connected to the negative electrode current collector layer, and the side surface sub-electrode of the negative electrode external electrode is located at a position not facing the side end portion of the positive electrode.

7. The laminated all-solid secondary battery according to claim 6, wherein:

the laminate has an upper surface and a lower surface formed as surfaces orthogonal to the lamination direction, and the positive electrode external electrode and the negative electrode external electrode have an upper surface sub-electrode or a lower surface sub-electrode.

8. The laminated all-solid secondary battery according to claim 7, wherein:

the tip end portion of the upper surface sub-electrode or the lower surface sub-electrode of the positive electrode external electrode is located at a position not opposed to the main surface of the negative electrode laminated at a position closest to the upper surface sub-electrode or the lower surface sub-electrode in the laminating direction.

9. The laminated all-solid secondary battery according to claim 7, wherein:

the tip of the upper surface sub-electrode or the lower surface sub-electrode of the negative external electrode is located at a position not opposed to the main surface of the positive electrode laminated at a position closest to the sub-electrode in the laminating direction.

10. The stacked all-solid secondary battery according to any one of claims 6 to 9, wherein:

the first side and the second side are located at opposing positions.

11. A stacked all-solid secondary battery characterized by comprising:

a laminate sintered body obtained by sintering a laminate in which a positive electrode having a positive electrode current collector layer and a positive electrode active material layer and a negative electrode having a negative electrode current collector layer and a negative electrode active material layer are laminated with a solid electrolyte layer interposed therebetween, the laminate sintered body having a side surface formed as a surface parallel to a lamination direction, the side surface including a first side surface on which the positive electrode current collector layer is exposed and a second side surface on which the negative electrode current collector layer is exposed;

a positive external electrode disposed on the first side surface; and

a negative external electrode disposed on the second side surface,

the positive electrode external electrode is electrically connected to the positive electrode collector layer, and at least one of an upper end and a lower end of the positive electrode external electrode in the stacking direction is located inside an upper end or a lower end of the stacked sintered body in the stacking direction,

the negative electrode external electrode is electrically connected to the negative electrode current collector layer, and at least one of an upper end and a lower end of the negative electrode external electrode in the stacking direction is located inside an upper end or a lower end of the stacked sintered body in the stacking direction.

12. The stacked all-solid secondary battery according to claim 11, wherein:

the laminated sintered body has an upper surface and a lower surface formed as planes orthogonal to the laminating direction,

the positive electrode external electrode and the negative electrode external electrode each have a sub-electrode extending to at least one of the upper surface and the lower surface.

13. A method for manufacturing a stacked all-solid-state secondary battery, comprising:

a step of obtaining a cell laminate which is formed by laminating a positive electrode cell and a negative electrode cell with a solid electrolyte layer therebetween and has solid electrolyte layers on both upper and lower surfaces in a laminating direction, the positive electrode cell being formed by arranging two or more positive electrodes having a positive electrode collector layer and a positive electrode active material layer along a surface direction of the positive electrode with a spacer therebetween, the negative electrode cell being formed by arranging two or more negative electrodes having a negative electrode collector layer and a negative electrode active material layer along a surface direction of the negative electrode with a spacer therebetween, the positive electrode cell and the negative electrode cell being laminated with the solid electrolyte layer therebetween such that the spacer of the positive electrode cell faces the negative electrode of the negative electrode cell and the spacer of the negative electrode cell faces the positive electrode of the positive electrode cell;

forming a first groove penetrating the partition of the positive electrode cell and a second groove penetrating the partition of the negative electrode cell along the stacking direction from one surface of the cell stack in the stacking direction;

filling the first groove and the second groove with a conductive material;

forming cuts that penetrate the first grooves filled with the conductive material and the second grooves filled with the conductive material, respectively, and cutting the unit laminated body in a laminating direction to obtain a unit laminated body sheet; and

and firing and sintering the unit laminate sheet.

14. A method for manufacturing a stacked all-solid-state secondary battery, comprising:

a step of obtaining a cell laminate in which a positive electrode cell and a negative electrode cell are laminated with a solid electrolyte layer interposed therebetween, and the solid electrolyte layer is provided on one of upper and lower surfaces in a lamination direction, the positive electrode cell being formed by arranging two or more positive electrodes each having a positive electrode collector layer and a positive electrode active material layer along a surface direction of the positive electrode with a spacer therebetween, the negative electrode cell being formed by arranging two or more negative electrodes each having a negative electrode collector layer and a negative electrode active material layer along a surface direction of the negative electrode with a spacer therebetween, the positive electrode cell and the negative electrode cell being laminated with the solid electrolyte layer interposed therebetween such that the spacer of the positive electrode cell faces the negative electrode of the negative electrode cell, and the spacer of the negative electrode cell faces the positive electrode of the positive electrode cell;

forming a first groove penetrating the partition of the positive electrode cell and a second groove penetrating the partition of the negative electrode cell along the stacking direction from a surface of the cell stack opposite to the surface having the solid electrolyte layer;

filling the first groove and the second groove with a conductive material;

forming a solid electrolyte layer on a surface of the cell laminate opposite to the surface having the solid electrolyte layer;

forming cuts that penetrate the first grooves filled with the conductive material and the second grooves filled with the conductive material, respectively, and cutting the unit laminated body in a laminating direction to obtain a unit laminated body sheet; and

and firing and sintering the unit laminate sheet.

Technical Field

The present invention relates to a laminated all-solid-state secondary battery and a method for manufacturing the same.

The present application claims priority on the basis of Japanese application No. 2019-045032, published 3/12 in 2019 and Japanese application No. 2019-045035, published 3/12 in 2019, and the contents thereof are incorporated herein.

Background

In recent years, the development of electronic technology has been attracting attention, and the reduction in size and weight, the reduction in thickness, and the multi-functionalization of portable electronic devices have been achieved. Along with this, there is a strong demand for reduction in size and weight, reduction in thickness, and improvement in reliability for batteries as power sources for electronic devices, and attention is being given to all-solid-state lithium ion secondary batteries using a solid electrolyte as an electrolyte.

As an all-solid-state lithium ion secondary battery, a laminated all-solid-state lithium ion secondary battery (hereinafter, referred to as a laminated all-solid-state secondary battery) in which a positive electrode having a positive electrode collector layer and a positive electrode active material layer and a negative electrode having a negative electrode collector layer and a negative electrode active material layer are alternately laminated with a solid electrolyte layer interposed therebetween is known.

In addition, there is known a laminated all-solid-state lithium-ion secondary battery (hereinafter, referred to as a laminated all-solid-state secondary battery) in which a positive electrode and a negative electrode are alternately laminated through a solid electrolyte layer and sintered.

In a laminated all-solid-state secondary battery, a positive electrode collector layer and a negative electrode collector layer are generally exposed at a side surface of a laminate, and a positive electrode external electrode electrically connected to the positive electrode collector layer and a negative electrode external electrode electrically connected to the negative electrode collector layer are provided at the side surface of the laminate (patent document 1). Patent document 1 discloses a stacked all-solid-state secondary battery in which an end of a positive electrode external electrode is located at a position facing a negative electrode, and an end of a negative electrode external electrode is located at a position facing the positive electrode.

In addition, in the laminated all-solid-state secondary battery, the positive electrode collector layer and the negative electrode collector layer are generally exposed at the side surface of the laminated sintered body, and a positive electrode external electrode electrically connected to the positive electrode collector layer and a negative electrode external electrode electrically connected to the negative electrode collector layer are provided at the side surface of the laminated body (patent document 2). The laminated all-solid secondary battery is generally manufactured as follows. First, a laminate is obtained by laminating a positive electrode and a negative electrode with a solid electrolyte layer interposed therebetween. Next, the obtained laminate was fired and sintered to obtain a laminate sintered body. Then, a conductive material paste is applied to the side surfaces of the obtained laminated sintered body by a dip coating method or a printing method, and the sintered body is heated to form a positive external electrode and a negative external electrode (patent document 3).

Documents of the prior art

Patent document

Patent document 1: japanese laid-open patent publication No. 2015-11864

Patent document 2: japanese patent laid-open publication No. 2014-192041

Patent document 3: japanese patent laid-open publication No. 2011-146202

Disclosure of Invention

Technical problem to be solved by the invention

However, with the recent increase in output of electronic devices, there is a demand for a stacked all-solid-state secondary battery that has an improved charge/discharge capacity and is capable of continuous discharge with a large instantaneous current, i.e., improved pulse discharge cycle characteristics. However, the conventional laminated all-solid-state secondary battery has a technical problem that it is difficult to improve both the charge/discharge capacity and the pulse discharge cycle characteristics.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a laminated all-solid-state secondary battery capable of improving charge/discharge capacity and pulse discharge cycle characteristics.

In addition, with the recent miniaturization of electronic devices, there is a demand for improvement in charge/discharge capacity and volumetric energy density in a stacked all-solid-state secondary battery. However, since the laminated all-solid-state secondary battery has a structure in which an external electrode for taking out the positive electrode and the negative electrode to the outside is provided on the surface of the laminate, there are the following problems: when the external electrode is provided, the volume becomes large and the volume energy density becomes small.

In addition, the laminated sintered body obtained in the production of the laminated all-solid-state secondary battery may shrink the current collector layers of the positive electrode and the negative electrode, and may be insufficiently exposed at the side surfaces. Therefore, when the external electrode is applied to the side surface of the laminated sintered body, the collector layer and the external electrode may have poor adhesion, and thus excellent charge/discharge capacity may not be obtained. Further, due to volume expansion and contraction accompanying charge and discharge reactions, cracks are likely to occur at the joint surface between the current collector layer and the external electrode, and excellent cycle characteristics cannot be obtained.

The present invention has been made in view of the above-described problems, and an object thereof is to provide a laminated all-solid-state secondary battery having excellent charge/discharge capacity, volumetric energy density, and cycle characteristics, and a method for manufacturing the same.

Means for solving the problems

As a result of intensive studies to solve the above-described problems, the inventors of the present invention have found that charge/discharge capacity and pulse discharge cycle characteristics can be improved by positioning the side end portion of the positive electrode external electrode in a position not facing the side end portion of the negative electrode and positioning the side end portion of the negative electrode external electrode in a position not facing the side end portion of the positive electrode in a stacked all-solid secondary battery. The reason is not necessarily clear, but it is considered that the reason is that the generation of parasitic capacitance (stray capacitance) between the positive external electrode and the negative electrode or between the negative external electrode and the positive electrode can be suppressed. The parasitic capacitance refers to a capacitance component not intended by a designer due to an internal physical structure of an electronic component.

That is, the present invention provides the following means to solve the above problems.

(1) A first aspect of the present invention provides a stacked all-solid secondary battery including: a laminate in which a positive electrode having a positive electrode collector layer and a positive electrode active material layer and a negative electrode having a negative electrode collector layer and a negative electrode active material layer are laminated with a solid electrolyte layer interposed therebetween, the laminate having a side surface formed as a plane parallel to the lamination direction, the side surface including a first side surface on which the positive electrode collector layer is exposed and a second side surface on which the negative electrode collector layer is exposed; a positive external electrode disposed on the first side surface; and a negative electrode external electrode provided on the second side surface, the positive electrode external electrode being electrically connected to the positive electrode current collector layer, and a side end portion of the positive electrode external electrode being located at a position not opposed to a side end portion of the negative electrode, the negative electrode external electrode being electrically connected to the negative electrode current collector layer, and a side end portion of the negative electrode external electrode being located at a position not opposed to a side end portion of the positive electrode.

(2) In the laminated all-solid secondary battery according to the aspect (1), the laminated all-solid secondary battery may be configured such that: the laminate has an upper surface and a lower surface formed as surfaces orthogonal to the lamination direction, and the positive electrode external electrode and the negative electrode external electrode each have a sub-electrode extending to at least one of the upper surface and the lower surface.

(3) In the laminated all-solid-state secondary battery according to the aspect (2), the structure may be such that: the tip end portion of the sub-electrode of the positive electrode external electrode is located at a position not opposed to the main surface of the negative electrode laminated at a position closest to the sub-electrode in the lamination direction.

(4) In the laminated all-solid-state secondary battery according to the aspect (2), the structure may be such that: the tip end portion of the sub-electrode of the negative external electrode is located at a position not opposed to the main surface of the positive electrode laminated at a position closest to the sub-electrode in the laminating direction.

(5) In the laminated all-solid-state secondary battery according to any one of the above (1) to (4), the laminated all-solid-state secondary battery may be configured such that: the first side and the second side are located at opposing positions.

(6) In the laminated all-solid secondary battery according to the aspect (1), the laminated all-solid secondary battery may be configured such that: the side surface sub-electrode of the positive electrode external electrode is located at a position not facing the side end portion of the negative electrode, the negative electrode external electrode is electrically connected to the negative electrode current collector layer, and the side surface sub-electrode of the negative electrode external electrode is located at a position not facing the side end portion of the positive electrode.

(7) In the laminated all-solid secondary battery according to the aspect (6), the structure may be such that: the laminate has an upper surface and a lower surface formed as surfaces orthogonal to the lamination direction, and the positive electrode external electrode and the negative electrode external electrode have an upper surface sub-electrode or a lower surface sub-electrode.

(8) In the laminated all-solid-state secondary battery according to the aspect (7), the structure may be such that: the tip end portion of the upper surface sub-electrode or the lower surface sub-electrode of the positive electrode external electrode is located at a position not opposed to the main surface of the negative electrode laminated at a position closest to the upper surface sub-electrode or the lower surface sub-electrode in the laminating direction.

(9) The following may be configured: the tip of the upper surface sub-electrode or the lower surface sub-electrode of the negative external electrode is located at a position not opposed to the main surface of the positive electrode laminated at a position closest to the sub-electrode in the laminating direction.

(10) In the laminated all-solid-state secondary battery according to any one of the above (6) to (9), the laminated all-solid-state secondary battery may be configured such that: the first side and the second side are located at opposing positions.

Further, the present inventors have made extensive studies to solve the above-mentioned problems, and as a result, they have found that in a laminated all-solid secondary battery, by forming at least one of the upper end and the lower end of the positive electrode external electrode and the negative electrode external electrode inside the upper end or the lower end of the laminate, the charge/discharge capacity, the volumetric energy density, and the cycle characteristics can be improved. The reason is not necessarily clear, but is considered as follows.

First, by forming the external electrodes of the positive electrode and the negative electrode of the stacked all-solid-state secondary battery inside the stacked body, it is possible to prevent the external electrodes of the positive electrode and the negative electrode from being formed at the ridge portions of the stacked body. Therefore, the occurrence of parasitic capacitance (stray capacitance) between the positive electrode external electrode and the negative electrode at the ridge portion, or between the negative electrode external electrode and the positive electrode at the ridge portion can be suppressed. Therefore, it is considered that the charge/discharge capacity can be improved. The parasitic capacitance refers to a capacitance component not intended by a designer due to an internal physical structure of an electronic component. Further, by forming the external electrodes of the positive electrode and the negative electrode inside the laminate, the positive electrode current collector and the negative electrode current collector can be electrically connected to the external electrodes without increasing the volume of the laminated all-solid secondary battery, and therefore, it is considered that the volumetric energy density becomes high.

The present inventors formed grooves in the laminate in such a manner that the current collector of the positive electrode and the current collector of the negative electrode are exposed at the side surfaces of the laminate before the laminate in which the positive electrode and the negative electrode were laminated with the solid electrolyte layer interposed therebetween was fired, that is, at the stage of non-firing, and filled the grooves with a conductive material. Next, the groove filled with the conductive material is cut, whereby an unfired laminated all-solid-state secondary battery in which the conductive material is formed into the positive electrode external electrode and the negative electrode external electrode can be manufactured. Accordingly, it was found that an unfired laminated all-solid-state battery in which the positive electrode external electrode and the positive electrode current collector were well bonded and the negative electrode external electrode and the negative electrode current collector were well bonded could be obtained in the unfired stage. Therefore, even when the laminate is fired, the positive electrode external electrode and the positive electrode current collector, and the negative electrode external electrode and the negative electrode current collector exhibit good bondability after firing, and thus a laminated all-solid-state secondary battery having excellent cycle characteristics can be obtained.

That is, the present invention provides the following means to solve the above problems.

(11) Another aspect of the present invention provides a stacked all-solid secondary battery including: a laminate sintered body obtained by sintering a laminate in which a positive electrode having a positive electrode current collector layer and a positive electrode active material layer and a negative electrode having a negative electrode current collector layer and a negative electrode active material layer are laminated with a solid electrolyte layer interposed therebetween, the laminate sintered body having a side surface formed as a surface parallel to a lamination direction, the side surface including a first side surface on which the positive electrode current collector layer is exposed and a second side surface on which the negative electrode current collector layer is exposed; a positive external electrode disposed on the first side surface; and a negative electrode external electrode provided on the second side surface, the positive electrode external electrode being electrically connected to the positive electrode current collector layer, at least one of an upper end portion and a lower end portion of the positive electrode external electrode in the stacking direction being positioned inside an upper end portion or a lower end portion of the stacked sintered body in the stacking direction, the negative electrode external electrode being electrically connected to the negative electrode current collector layer, and at least one of an upper end portion and a lower end portion of the negative electrode external electrode in the stacking direction being positioned inside an upper end portion or a lower end portion of the stacked sintered body in the stacking direction.

(12) In the laminated all-solid-state secondary battery according to the aspect (11), the structure may be such that: the laminated sintered body has an upper surface and a lower surface formed as surfaces orthogonal to the laminating direction, and the positive electrode external electrode and the negative electrode external electrode each have a sub-electrode extending to at least one of the upper surface and the lower surface.

(13) Another embodiment of the present invention provides a method for manufacturing a stacked all-solid-state secondary battery, including: a step of obtaining a cell laminate which is formed by laminating a positive electrode cell and a negative electrode cell with a solid electrolyte layer therebetween and has solid electrolyte layers on both upper and lower surfaces in a laminating direction, the positive electrode cell being formed by arranging two or more positive electrodes having a positive electrode collector layer and a positive electrode active material layer along a surface direction of the positive electrode with a spacer therebetween, the negative electrode cell being formed by arranging two or more negative electrodes having a negative electrode collector layer and a negative electrode active material layer along a surface direction of the negative electrode with a spacer therebetween, the positive electrode cell and the negative electrode cell being laminated with the solid electrolyte layer therebetween such that the spacer of the positive electrode cell faces the negative electrode of the negative electrode cell and the spacer of the negative electrode cell faces the positive electrode of the positive electrode cell; forming a first groove penetrating the partition of the positive electrode cell and a second groove penetrating the partition of the negative electrode cell along the stacking direction from one surface of the cell stack in the stacking direction; filling the first groove and the second groove with a conductive material; forming cuts that penetrate the first grooves filled with the conductive material and the second grooves filled with the conductive material, respectively, and cutting the unit laminated body in a laminating direction to obtain a unit laminated body sheet; and a step of firing and sintering the unit laminated body sheet.

(14) Another aspect of the present invention provides a method for manufacturing a stacked all-solid-state secondary battery, including: a step of obtaining a cell laminate in which a positive electrode cell and a negative electrode cell are laminated with a solid electrolyte layer interposed therebetween, and the solid electrolyte layer is provided on one of upper and lower surfaces in a lamination direction, the positive electrode cell being formed by arranging two or more positive electrodes each having a positive electrode collector layer and a positive electrode active material layer along a surface direction of the positive electrode with a spacer therebetween, the negative electrode cell being formed by arranging two or more negative electrodes each having a negative electrode collector layer and a negative electrode active material layer along a surface direction of the negative electrode with a spacer therebetween, the positive electrode cell and the negative electrode cell being laminated with the solid electrolyte layer interposed therebetween such that the spacer of the positive electrode cell faces the negative electrode of the negative electrode cell, and the spacer of the negative electrode cell faces the positive electrode of the positive electrode cell; forming a first groove penetrating the partition of the positive electrode cell and a second groove penetrating the partition of the negative electrode cell along the stacking direction from a surface of the cell stack opposite to the surface having the solid electrolyte layer; filling the first groove and the second groove with a conductive material; forming a solid electrolyte layer on a surface of the cell laminate opposite to the surface having the solid electrolyte layer; forming cuts that penetrate the first grooves filled with the conductive material and the second grooves filled with the conductive material, respectively, and cutting the unit laminated body in a laminating direction to obtain a unit laminated body sheet; and a step of firing and sintering the unit laminated body sheet.

Effects of the invention

The present invention can provide a laminated all-solid-state secondary battery capable of improving charge/discharge capacity and pulse discharge cycle characteristics.

Further, a laminated all-solid secondary battery excellent in charge/discharge capacity, volumetric energy density and cycle characteristics, and a method for manufacturing the same can be provided.

Drawings

Fig. 1 is a schematic diagram of a laminated all-solid secondary battery according to a first embodiment, in which (a) is a plan view as viewed from above, and (b) is a bottom view as viewed from below.

Fig. 2 is a sectional view taken along line II-II of fig. 1.

Fig. 3 is a schematic diagram of a laminated all-solid secondary battery according to a second embodiment, in which (a) is a plan view as viewed from above, and (b) is a bottom view as viewed from below.

Fig. 4 is a sectional view taken along line IV-IV of fig. 3.

Fig. 5 is a schematic diagram of a laminated all-solid secondary battery according to a third embodiment, in which (a) is a plan view as viewed from above, and (b) is a bottom view as viewed from below.

Fig. 6 is a sectional view taken along line VI-VI of fig. 5.

Fig. 7 is a schematic diagram of a laminated all-solid secondary battery according to a fourth embodiment, in which (a) is a top view and (b) is a bottom view.

Fig. 8 is a sectional view taken along line VIII-VIII of fig. 7.

Fig. 9 is a schematic diagram of a laminated all-solid secondary battery according to a fifth embodiment, in which (a) is a top view seen from above, and (b) is a bottom view seen from below.

Fig. 10 is a cross-sectional view taken along line X-X of fig. 9.

Fig. 11 is a schematic diagram of a conventional laminated all-solid-state secondary battery, in which (a) is a plan view seen from above and (b) is a bottom view seen from below.

Fig. 12 is a sectional view taken along line XII-XII of fig. 11.

Fig. 13 is a schematic diagram of a laminated all-solid secondary battery according to a sixth embodiment, in which (a) is a top view and (b) is a bottom view.

Fig. 14 is a sectional view taken along line II-II of fig. 13.

Fig. 15 is a flowchart of a method for manufacturing a laminated all-solid secondary battery according to a sixth embodiment.

Fig. 16 is a schematic diagram of a cell laminate used in the method for manufacturing a laminated all-solid secondary battery according to the sixth embodiment, where (a) is a plan view and (b) is a sectional view taken along line IVb-IVb of (a).

Fig. 17 is a schematic view showing a state in which a groove is provided in the cell laminate of fig. 16, wherein (a) is a plan view, and (b) is a cross-sectional view taken along the line Vb-Vb of (a).

Fig. 18 is a cross-sectional view showing a state in which the grooves of the cell laminate of fig. 17 are filled with electrodes.

Fig. 19 is a cross-sectional view showing a state in which the sub-electrode is connected to the electrode of the cell laminate of fig. 18.

Fig. 20 is a cross-sectional view showing a state in which the cell laminate of fig. 19 is cut.

Fig. 21 is a sectional view of a unit laminate used in the method for manufacturing a laminated all-solid secondary battery according to the ninth embodiment.

Fig. 22 is a cross-sectional view showing a state in which a groove is provided in the cell stack of fig. 21.

Fig. 23 is a cross-sectional view showing a state in which the cell stack of fig. 21 has electrodes filled in the grooves.

Fig. 24 is a cross-sectional view showing a state in which a solid electrolyte layer is formed on the surface of the upper surface of the cell laminate of fig. 23.

Fig. 25 is a cross-sectional view showing a state in which the cell laminate of fig. 24 is cut.

Fig. 26 is a sectional view of the laminated all-solid secondary battery according to the seventh embodiment, in which (a) is a top view and (b) is a bottom view.

Fig. 27 is a sectional view taken along line II-II of fig. 26.

Fig. 28 is a sectional view of the laminated all-solid secondary battery according to the eighth embodiment, in which (a) is a top view seen from above, and (b) is a bottom view seen from below.

Fig. 29 is a sectional view taken along line II-II of fig. 28.

Fig. 30 is a sectional view of the laminated all-solid secondary battery according to the ninth embodiment, in which (a) is a top view and (b) is a bottom view.

Fig. 31 is a sectional view taken along line II-II of fig. 30.

Fig. 32 is a schematic diagram of a conventional laminated all-solid-state secondary battery, in which (a) is a plan view seen from above and (b) is a bottom view seen from below.

Fig. 33 is a cross-sectional view taken along line XVIII-XVIII of fig. 32.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings as appropriate. In the drawings used in the following description, portions that are characteristic for the convenience are sometimes enlarged for easy understanding of the features of the present invention. Therefore, the dimensional ratios of the respective components shown in the drawings and the like may be different from the actual ones. The materials, dimensions, and the like illustrated in the following description are merely examples, and the present invention is not limited to these, and can be implemented by appropriately changing the materials, dimensions, and the like within a range in which the effects of the present invention can be achieved.

[ conventional laminated all-solid-state secondary battery ]

First, a conventional laminated all-solid secondary battery will be described.

Fig. 11 is a schematic diagram of a conventional laminated all-solid-state secondary battery, in which (a) is a plan view seen from above and (b) is a bottom view seen from below. Fig. 12 is a sectional view taken along line XII-XII of fig. 11.

In the drawings of the present specification, in all of the top and bottom views of the laminated all-solid-state secondary battery, at least a side edge sufficient for preventing short-circuiting is provided between the side surface of the positive electrode or the negative electrode and the side surface of the outer wall of the all-solid-state secondary battery. Even if the two are depicted in contact in the drawing, a side edge that is thin enough not to be illustrated is provided between the two.

As shown in fig. 11 and 12, the laminated all-solid-state secondary battery 310 includes a laminate 320 in which a positive electrode 330 and a negative electrode 340 are laminated with a solid electrolyte layer 350 interposed therebetween. The positive electrode 330 has a positive electrode collector layer 331 and a positive electrode active material layer 332. The anode 340 has an anode current collector layer 341 and an anode active material layer 342. The stacked body 320 is a hexahedron, and has: 4 side surfaces (a first side surface 321, a second side surface 322, a third side surface 323, and a fourth side surface 324) formed as surfaces parallel to the stacking direction; and an upper surface 325 formed above and a lower surface 326 formed below as surfaces orthogonal to the stacking direction. The positive electrode collector layer is exposed on the first side 321, and the negative electrode collector layer is exposed on the second side 322. The third side 323 is a side on the right side when viewed from the first side 321 with the top 325 facing upward, and the fourth side 324 is a side on the left side when viewed from the first side 321 with the top 325 facing upward.

A positive electrode external electrode 360 electrically connected to the positive electrode current collector layer 331 is provided on the first side 321 of the laminate 320. The positive electrode external electrode 360 includes: a side sub-electrode 360a extending to the third and fourth sides 323 and 324; an upper surface sub-electrode 360b extending to the upper surface 325; and a lower surface sub-electrode 360c extending to the lower surface 326. That is, the cross-sectional shape of the positive electrode outer electrode 360 is コ, and has 5 planes. The end of the side sub-electrode 360a (the end of the positive external electrode 360) is positioned to face the negative electrode 340 (the side of the negative electrode 340). Here, the facing position refers to a position where the side sub-electrode 360a and the negative electrode 340 overlap each other when the stacked all-solid-state secondary battery 310 is seen through. The end of the upper surface sub-electrode 360b (the upper end of the positive electrode outer electrode 360) is positioned to face the negative electrode 340 (the upper surface of the negative electrode 340). The end of the lower surface sub-electrode 360c (the lower end of the positive electrode external electrode 360) is positioned to face the negative electrode 340 (the lower surface of the negative electrode 340).

A negative electrode external electrode 370 electrically connected to the negative electrode current collector layer 341 is provided on the second side surface 322 of the laminate 320. The negative external electrode 370 has: a side sub-electrode 370a extending to the third and fourth sides 323 and 324; an upper surface sub-electrode 370b extending to the upper surface 325; and a lower surface sub-electrode 370c extending to the lower surface 326. That is, the negative electrode 370 has a cross-sectional shape of コ and 5 planes. The end of the side sub-electrode 370a (the end of the negative external electrode 370) is positioned to face the positive electrode 330 (the side surface of the positive electrode 330). The end of the upper surface sub-electrode 370b (the upper end of the negative external electrode 370) is positioned to face the positive electrode 330 (the upper surface of the positive electrode 330). The end of the lower sub-electrode 370c (the lower end of the negative external electrode 370) is positioned to face the positive electrode 330 (the lower surface of the positive electrode 330).

In the laminated all-solid secondary battery 310, the ends of the side sub-electrode 360a, the upper sub-electrode 360b, and the lower sub-electrode 360c of the positive electrode external electrode 360 extend to positions facing the negative electrode 340, and the ends of the side sub-electrode 370a, the upper sub-electrode 370b, and the lower sub-electrode 370c of the negative electrode external electrode 370 extend to positions facing the positive electrode 330. Therefore, as indicated by arrows P, parasitic capacitances of the negative electrode 340 are generated in 4 places between the positive external electrode 360, the side surface sub-electrode 360a, and the lower surface sub-electrode 360c, and the negative electrode 340. As indicated by arrow Q, the parasitic capacitance of the positive electrode 330 is generated at 4 locations between the negative external electrode 370, the side sub-electrode 370a, and the upper sub-electrode 370b, and the positive electrode 330. In order to increase the charge/discharge capacity of the laminated all-solid-state secondary battery 310, it is preferable that the area of the positive electrode 330 facing the negative electrode 340 is large, that is, the interval between the positive electrode 330 and the second side surface 322 is narrow, and the interval between the negative electrode 340 and the first side surface 321 is narrow. However, when the distance between the positive electrode 330 and the second side surface 322 is narrowed and the distance between the negative electrode 340 and the first side surface 321 is narrowed, parasitic capacitance is easily generated. When the parasitic capacitance is generated, the current consumption other than the charge-discharge reaction is reduced, and therefore, the continuous discharge characteristic (pulse discharge cycle characteristic) of a large instantaneous current is reduced. Therefore, it is difficult for the conventional laminated all-solid secondary battery 310 to improve both the charge/discharge capacity and the pulse discharge cycle characteristics.

[ first embodiment ]

Next, a laminated all-solid secondary battery according to a first embodiment of the present invention will be described.

Fig. 1 is a schematic diagram of a laminated all-solid secondary battery according to a first embodiment, in which (a) is a plan view as viewed from above, and (b) is a bottom view as viewed from below. Fig. 2 is a sectional view taken along line II-II of fig. 1. In the description of the first embodiment, the same reference numerals are given to the constituent elements that overlap with those of the conventional stacked all-solid secondary battery 310, and the description thereof will be omitted.

As shown in fig. 1 and 2, in the laminated all-solid secondary battery 311 according to the present embodiment, the positive external electrode 361 is provided on the first side surface 321 of the laminate 320. A negative electrode external electrode 371 is provided on the second side 322 of the laminate 320.

The positive electrode external electrode 361 is an electrode having a cross-sectional shape コ with an upper surface sub-electrode 361b extending to the upper surface 325 and a lower surface sub-electrode 361c extending to the lower surface 326. The end of the upper surface sub-electrode 361b (the upper end of the positive electrode external electrode 361) is positioned to face the negative electrode 340 (the upper surface of the negative electrode 340). The end of the lower sub-electrode 361c (the lower end of the positive external electrode 361) is positioned to face the negative electrode 340 (the lower surface of the negative electrode 340). The positive electrode external electrode 361 has no side sub-electrode extending to the third and fourth sides 323 and 324. However, if the end of the side sub-electrode (the side end of the negative electrode external electrode 371) is located at a position not facing the negative electrode 340 (the side surface of the negative electrode 340), the positive electrode external electrode 361 may have a side sub-electrode. Here, the non-facing position is a position where the side sub-electrode and the negative electrode 340 do not overlap with each other in the case of the see-through laminated all-solid-state secondary battery 311. When the positive electrode external electrode 361 has the side sub-electrode, the end of the side sub-electrode is preferably located within a range of 10 μm or less from the end of the third side 323 and the fourth side 324 on the first side 321 side.

The negative external electrode 371 is an electrode having a cross-sectional shape コ with an upper surface sub-electrode 371b extending to the upper surface 325 and a lower surface sub-electrode 371c extending to the lower surface 326. The end of the upper surface sub-electrode 371b (the upper end of the negative external electrode 371) is positioned to face the positive electrode 330 (the upper surface of the positive electrode 330). The end of the lower surface sub-electrode 371c (the lower end of the negative electrode external electrode 371) is located at a position facing the positive electrode 330 (the lower surface of the positive electrode 330). The negative external electrode 371 does not have a side sub-electrode extending to the third and fourth sides 323 and 324. However, if the end of the side sub-electrode (the side end of the positive electrode external electrode 361) is located at a position not facing the positive electrode 330 (the side surface of the positive electrode 330), the negative electrode external electrode 371 may have a side sub-electrode. Here, the non-facing position is a position where the side sub-electrode and the positive electrode 330 do not overlap with each other in the case of the see-through laminated all-solid-state secondary battery 311. When the negative electrode external electrode 371 has the side sub-electrode, the end of the side sub-electrode is preferably located within a range of 10 μm or less from the end of the third side 323 and the fourth side 324 on the side of the second side 322.

In the laminated all-solid secondary battery 311 according to the present embodiment, as indicated by the arrow P, the occurrence of the parasitic capacitance of the negative electrode 340 is suppressed at two locations between the positive electrode external electrode 361 and the lower surface sub-electrode 362c and the negative electrode 340. Further, as indicated by the arrow Q, the occurrence of the parasitic capacitance of the positive electrode 330 is suppressed at two locations between the negative external electrode 371 and the upper surface sub-electrode 371b and the positive electrode 330. As described above, the laminated all-solid secondary battery 311 according to the present embodiment can suppress the occurrence of parasitic capacitance and improve the pulse discharge cycle characteristics, as compared with the conventional laminated all-solid secondary battery 310. In addition, since the generation of parasitic capacitance can be suppressed, the current distribution accompanying the charge and discharge reaction becomes uniform, and the battery reaction can be performed uniformly. As a result, the charge/discharge capacity is improved.

In the laminated all-solid secondary battery 311, the materials of the cathode current collector layer 331, the cathode active material layer 332, the anode current collector layer 341, the anode active material layer 342, the solid electrolyte layer 350, the cathode external electrode 361, and the anode external electrode 371 are not particularly limited, and known materials used in conventional laminated all-solid secondary batteries can be used.

As the material of the positive electrode collector layer 331 and the negative electrode collector layer 341, a material having high electrical conductivity is preferably used. Specifically, metals such as silver, palladium, gold, platinum, aluminum, copper, and nickel can be used. In addition, a mixture of the metal and the positive electrode active material may be used as the material of the positive electrode collector layer 331, and a mixture of the metal and the negative electrode active material may be used as the material of the negative electrode collector layer 341.

The positive electrode active material layer 332 and the negative electrode active material layer 342 contain a positive electrode active material and a negative electrode active material that can transfer electrons. In addition, a conductive aid, a binder, or the like may be contained. The positive electrode active material and the negative electrode active material are preferably capable of efficiently inserting and extracting lithium ions.

As the positive electrode active material and the negative electrode active material, for example, a transition metal oxide or a transition metal composite oxide is preferably used. Specifically, lithium manganese composite oxide Li may be used₂Mn_aMa_1-aO₃(0.8. ltoreq. a.ltoreq.1, Ma. Co, Ni), lithium cobaltate (LiCoO)₂) Lithium nickelate (LiNiO)₂) Lithium manganese spinel (LiMn)₂O₄) The general formula is as follows: LiNi_xCo_yMn_zO₂A complex metal oxide represented by (x + y + z ≦ 1, 0. ltoreq. x.ltoreq.1, 0. ltoreq. y.ltoreq.1, 0. ltoreq. z.ltoreq.1), and a lithium vanadium compound (LiV)₂O₅) Olivine type LiMbPO₄(where Mb is 1 or more elements selected from the group consisting of Co, Ni, Mn, Fe, Mg, Nb, Ti, Al and Zr), lithium vanadium phosphate (Li)₃V₂(PO₄)₃Or LiVOPO₄) From Li₂MnO₃-LiMcO₂(Mc＝Mn、Co、Li-excess solid solution represented by Ni) and lithium titanate (Li)₄Ti₅O₁₂) From Li_sNi_tCo_uAl_vO₂And (0.9 < s < 1.3, 0.9 < t + u + v < 1.1).

The positive electrode active material and the negative electrode active material may be selected according to a solid electrolyte described later. For example, in the use of Li_1+nAl_nTi_2-n(PO₄)₃(0. ltoreq. n. ltoreq.0.6) As the solid electrolyte, LiVOPO is preferably used as the positive electrode active material and the negative electrode active material₄And Li₃V₂(PO₄)₃One or both of them. In this case, the interface between the positive electrode active material layer 332 and the negative electrode active material layer 342 and the solid electrolyte layer 350 is strongly bonded. In addition, the contact area of the interface between the positive electrode active material layer 332 and the negative electrode active material layer 342 and the solid electrolyte layer 350 can be increased.

The solid electrolyte layer 350 contains a solid electrolyte. As the solid electrolyte, a material having low electron conductivity and high lithium ion conductivity is preferably used. Specifically, for example, it is preferably selected from La_0.51Li_0.34TiO_2.94And La_0.5Li_0.5TiO₃Isoperovskite compound, Li₁₄Zn(GeO₄)₄Isolithium Super Ion Conductor (LISICON) type compound, and Li₇La₃Zr₂O₁₂Isogarnet-type compound, LiZr₂(PO₄)₃、Li_1.3Al_0.3Ti_1.7(PO₄)₃And Li_1.5Al_0.5Ge_1.5(PO₄)₃Sodium Isoionic Conductor (NASICON) type compound and Li_3.25Ge_0.25P_0.75S₄And Li₃PS₄Isothiolithium super ion conductor (Thio-lithium) type compound, 50Li₄SiO₄·50Li₃BO₃、Li₂S-P₂S₅And Li₂O-Li₃O₅-SiO₂Isoglass compound, Li₃PO₄、Li_3.5Si_0.5P_0.5O₄And Li_2.9PO_3.3N_0.46Isophosphoric acid compound, Li_2.9PO_3.3N_0.46(LIPON) and Li_3.6Si_0.6P_0.4O₄Iso-amorphous, Li_1.07Al_0.69Ti_1.46(PO₄)₃And Li_1.5Al_0.5Ge_1.5(PO₄)₃And so on, and at least 1 of the glass-ceramics.

As the material of the positive electrode external electrode 361 and the negative electrode external electrode 371, a material having high electrical conductivity is preferably used. For example, silver, gold, platinum, aluminum, copper, tin, nickel may be used.

(method for manufacturing laminated all-solid-state secondary battery)

Next, a method for manufacturing the laminated all-solid secondary battery 311 according to the present embodiment will be described.

The stacked all-solid secondary battery 311 can be manufactured, for example, by a method including the steps of: a paste preparation step of preparing a paste for each member constituting the laminate 320; a cell production step of producing a positive electrode cell and a negative electrode cell using the produced paste; a lamination step of alternately laminating the obtained positive electrode cell and negative electrode cell to produce a laminated structure; a cutting step of cutting the obtained laminated structure into a predetermined shape; a firing step of firing the stacked structure to obtain a stacked body 320; and an external electrode forming step of forming external electrodes (the positive external electrode 361 and the negative external electrode 371) on the side surfaces of the obtained laminate 320.

< preparation Process of paste >

In the paste preparation step, the respective members of the positive electrode collector layer, the positive electrode active material layer, the solid electrolyte layer, the negative electrode collector layer, the negative electrode active material layer, and the external electrode are pasted. The method of making the paste is not particularly limited, and for example, the paste can be prepared by mixing the powders of the above-mentioned respective members and a vehicle. As a mixing device for producing the paste, a conventionally known mixing device such as a bead mill, a planetary paste mixer, an automatic attritor, a three-roll mill, a high shear mixer, a planetary mixer, or the like can be used. Here, the vehicle is a generic term for a medium in a liquid phase, and includes a solvent, a binder, and the like. The binder contained in the paste of each member is not particularly limited, and a polyvinyl acetal resin, a polyvinyl butyral resin, a terpineol resin, an ethyl cellulose resin, an acrylic resin, a polyurethane resin, a vinyl acetate resin, a polyvinyl alcohol resin, or the like can be used. These resins may be used alone in 1 kind, or 2 or more kinds may be used in combination.

In addition, the paste of each material may contain a plasticizer. The type of plasticizer is not particularly limited, and phthalic acid esters such as dioctyl phthalate and diisononyl phthalate can be used.

By the above-described method, a paste for a positive electrode collector layer, a paste for a positive electrode active material layer, a paste for a solid electrolyte layer, a paste for a negative electrode active material layer, and a paste for a negative electrode collector layer were prepared.

< Process for producing cell >

The positive electrode unit is a laminate having a positive electrode obtained by sequentially laminating a positive electrode active material layer, a positive electrode collector layer, and a positive electrode active material layer on a solid electrolyte layer green sheet. The positive electrode unit may be fabricated as follows.

First, the prepared paste for a solid electrolyte layer is applied to a substrate such as a polyethylene terephthalate (PET) film to a desired thickness and dried to prepare a green sheet for a solid electrolyte layer. The method of applying the paste for the solid electrolyte layer is not particularly limited, and known methods such as a doctor blade method, a die coating method, a comma coating method, and a gravure coating method can be used. Next, a positive electrode active material layer paste, a positive electrode collector layer paste, and a positive electrode active material layer paste were sequentially printed on the solid electrolyte layer green sheet by a screen printing method and dried, thereby forming a positive electrode in which a positive electrode active material layer, a positive electrode collector layer, and a positive electrode active material layer were sequentially stacked. Further, in order to fill the difference in height between the solid electrolyte layer green sheet and the positive electrode, a solid electrolyte layer paste is printed on a region (edge) other than the positive electrode by a screen printing method and dried, thereby forming a solid electrolyte layer having the same height as the positive electrode. Then, the substrate was peeled off to obtain a positive electrode unit in which a positive electrode was formed on the solid electrolyte layer green sheet.

The negative electrode unit is a laminate having a negative electrode obtained by sequentially laminating a negative electrode active material layer, a negative electrode current collector layer, and a negative electrode active material layer on a solid electrolyte layer green sheet. The negative electrode unit can be produced in the same manner as the above-described method for producing the positive electrode unit, except that the paste for the negative electrode active material layer and the paste for the negative electrode current collector layer are used instead of the paste for the positive electrode current collector layer and the paste for the positive electrode active material layer.

< laminating Process >

In the stacking step, the positive electrode cells and the negative electrode cells are alternately stacked. In this way, a stacked structure including a plurality of positive electrode cells and negative electrode cells is produced.

Then, the produced laminated structure is collectively pressed and bonded by a die press, a Warm Isostatic Press (WIP), a Cold Isostatic Press (CIP), a hydrostatic press, or the like, and the adhesion between the positive electrode unit and the negative electrode unit can be improved. The pressurization is preferably carried out simultaneously with the heating, and may be carried out at 40 to 95 ℃.

< cutting step >

In the cutting step, the produced laminated structure is cut along the laminating direction of the laminated structure so that the positive electrode collector layer of the positive electrode cell and the negative electrode collector layer of the negative electrode cell are exposed at the side surface of the laminated structure.

As a device for cutting the laminated structure, a dicing blade, a fine laser processing machine, or the like can be used.

< firing Process >

In the firing step, the stacked structure is fired and sintered to obtain a stacked body 320 of the stacked all-solid secondary battery 311. By firing, the solid electrolyte layer, the electrode layer, and the collector layer are densified, and desired electrical characteristics can be obtained. In the case where the material constituting the collector layer is not suitable for heat treatment in an oxidizing atmosphere, firing may be performed in a non-oxidizing atmosphere. The firing temperature is, for example, 600 ℃ to 1000 ℃. The firing time is, for example, in the range of 0.1 hour to 3 hours. The non-oxidizing atmosphere may be a nitrogen atmosphere, an argon atmosphere, a mixed nitrogen-hydrogen atmosphere, or the like.

Before the firing step, binder removal treatment may be performed as a step different from the firing step. By thermally decomposing the binder component contained in the laminated structure before firing, rapid decomposition of the binder component in the firing step can be suppressed. The binder removal treatment is performed by, for example, heating in a non-oxidizing atmosphere at a temperature equal to or higher than the decomposition temperature of the binder component and lower than the sintering temperature of the laminated structure (usually, in the range of 300 ℃ to 800 ℃) for 0.1 hour to 10 hours.

< external electrode Forming Process >

In the external electrode forming step, external electrodes are formed on the side surfaces of the obtained laminated body 320 using a conductive material paste for external electrodes. Specifically, the positive electrode external electrode 361 is formed in a predetermined shape on the first side surface 321 of the laminate 320, and the negative electrode external electrode 371 is formed in a predetermined shape on the second side surface 322 of the laminate 320, and then the sintering process is performed. As a method for forming the positive electrode external electrode 361 and the negative electrode external electrode 371, a known method such as a screen printing method, a sputtering method, a dip coating method, a spray coating method, or the like can be used. As a method for forming the positive electrode external electrode 361 and the negative electrode external electrode 371 so as to have a predetermined shape by using a screen printing method, a sputtering method, a dip coating method, or a spray coating method, for example, the following methods can be used: the side surfaces of the stacked body 320 are shielded from regions other than the region where the external electrodes are to be formed by a jig for shielding, a tape, or the like. The conditions of the sintering treatment vary depending on the type of the metal material of the external electrode, but the sintering treatment can be performed by heating to a temperature of 200 ℃ to 600 ℃ in a reducing atmosphere. In order to improve the wettability between the external electrode and the solder, a nickel (Ni) layer, a tin (Sn) layer, or the like may be formed on the surface of the external electrode by plating, sputtering, or the like.

Before the external electrode forming step, the laminate 320 may be put into a cylindrical container together with an abrasive such as alumina and roll-polished. This enables chamfering of the corners of the stacked body 320. As another method, the polishing may be performed by sandblasting.

[ second embodiment ]

Next, a laminated all-solid secondary battery according to a second embodiment of the present invention will be described.

Fig. 3 is a schematic diagram of a laminated all-solid secondary battery according to a second embodiment, in which (a) is a plan view as viewed from above, and (b) is a bottom view as viewed from below. Fig. 4 is a sectional view taken along line IV-IV of fig. 3. In the description of the second embodiment, the same reference numerals are given to the constituent elements that overlap with those of the laminated all-solid secondary battery 311 of the first embodiment, and the description thereof will be omitted.

As shown in fig. 3 and 4, in the laminated all-solid secondary battery 312 according to the present embodiment, the positive electrode external electrode 362 is provided on the first side 321 of the laminate 320. A negative external electrode 372 is provided on the second side 322 of the stacked body 320.

The positive electrode external electrode 362 is an electrode having an L-shaped cross-sectional shape having a lower surface sub-electrode 362c extending to the lower surface 326. The end of the lower surface sub-electrode 362c (the lower end of the positive electrode external electrode 362) is located at a position not facing the negative electrode 340 (the lower surface of the negative electrode 340). The positive electrode external electrode 362 does not have a side sub-electrode extending to the third side 323 and the fourth side 324, and does not have the upper surface sub-electrode 361b in the laminated all-solid secondary battery 311 of the first embodiment.

The negative external electrode 372 has a lower surface sub-electrode 372c extending to the lower surface 326 and has an L-shaped cross-sectional shape. The end of the lower surface sub-electrode 372c (the lower end of the negative external electrode 372) is positioned to face the positive electrode 330 (the lower surface of the positive electrode 330). The negative electrode external electrode 372 does not have a side sub-electrode extending to the third side 323 and the fourth side 324, and does not have the upper surface sub-electrode 371b in the laminated all-solid secondary battery 311 of the first embodiment.

In the laminated all-solid secondary battery 312 according to the present embodiment, as indicated by the arrow P, the occurrence of parasitic capacitance in the negative electrode 340 is suppressed at two locations between the positive external electrode 362 and the lower surface sub-electrode 362c and the negative electrode 340. Further, as indicated by an arrow Q, the generation of the parasitic capacitance of the positive electrode 330 is suppressed to a portion between the negative external electrode 372 and the positive electrode 330. As described above, the laminated all-solid secondary battery 312 according to the present embodiment can suppress the occurrence of parasitic capacitance more than the laminated all-solid secondary battery 311 according to the first embodiment, and therefore can improve the pulse discharge cycle characteristics and the charge/discharge capacity more.

[ third embodiment ]

Next, a laminated all-solid secondary battery according to a third embodiment of the present invention will be described.

Fig. 5 is a schematic diagram of a laminated all-solid secondary battery according to a third embodiment, in which (a) is a plan view as viewed from above, and (b) is a bottom view as viewed from below. Fig. 6 is a sectional view taken along line VI-VI of fig. 5. In the description of the third embodiment, the same reference numerals are given to the constituent elements that overlap with those of the laminated all-solid secondary battery 311 of the first embodiment, and the description thereof will be omitted.

As shown in fig. 5 and 6, in the laminated all-solid secondary battery 313 according to the present embodiment, the positive electrode external electrode 363 is provided on the first side 321 of the laminated body 320. A negative electrode external electrode 373 is provided on the second side 322 of the stacked body 320.

The positive electrode external electrode 363 is an electrode having a cross-sectional shape コ not having a side sub-electrode extending to the third side 323 and the fourth side 324 but having an upper surface sub-electrode 363b extending to the upper surface 325 and a lower surface sub-electrode 363c extending to the lower surface 326. The end of the upper surface sub-electrode 363b (the upper end of the positive electrode external electrode 363) is located at a position not opposed to the negative electrode 340 (the upper surface of the negative electrode 340). The end of the lower surface sub-electrode 363c (the lower end of the positive electrode external electrode 363) is located at a position not facing the negative electrode 340 (the lower surface of the negative electrode 340).

The negative external electrode 373 is an electrode having a cross-sectional shape of コ, which does not have a side sub-electrode extending to the third side 323 and the fourth side 324, but has an upper surface sub-electrode 373b extending to the upper surface 325 and a lower surface sub-electrode 373c extending to the lower surface 326. The end portion of the upper surface sub-electrode 373b (the upper end portion of the negative electrode external electrode 373) is located at a position not facing the positive electrode 330 (the upper surface of the positive electrode 330). The end portion of the lower surface sub-electrode 373c (the lower end portion of the negative electrode external electrode 371) is located at a position not facing the positive electrode 330 (the lower surface of the positive electrode 330).

In the laminated all-solid-state secondary battery 313 according to the present embodiment, as indicated by the arrow P, the occurrence of the parasitic capacitance of the negative electrode 340 is suppressed to one portion between the positive external electrode 362 and the negative electrode 340. Further, as indicated by an arrow Q, the generation of the parasitic capacitance of the positive electrode 330 is suppressed to a portion between the negative external electrode 372 and the positive electrode 330. As described above, the laminated all-solid secondary battery 313 according to the present embodiment can further suppress the occurrence of parasitic capacitance as compared with the laminated all-solid secondary battery 311 according to the first embodiment, and therefore can further improve the pulse discharge cycle characteristics and the charge/discharge capacity.

[ fourth embodiment ]

Next, a laminated all-solid secondary battery according to a fourth embodiment of the present invention will be described.

Fig. 7 is a schematic diagram of a laminated all-solid secondary battery according to a fourth embodiment, in which (a) is a top view and (b) is a bottom view. Fig. 8 is a sectional view taken along line VIII-VIII of fig. 7. In the description of the fourth embodiment, the same reference numerals are given to the constituent elements that overlap with those of the laminated all-solid secondary battery 311 of the first embodiment, and the description thereof will be omitted.

As shown in fig. 7 and 8, in the laminated all-solid secondary battery 314 according to the present embodiment, the positive electrode external electrode 364 is provided on the first side surface 321 of the laminated body 320. A negative external electrode 374 is provided on the second side 322 of the stacked body 320.

The positive electrode external electrode 364 is an electrode having an L-shaped cross-sectional shape having a lower surface sub-electrode 364c extending to the lower surface 326. The end of the lower surface sub-electrode 364c (the lower end of the positive electrode external electrode 364) is located at a position not facing the negative electrode 340 (the lower surface of the negative electrode 340). The positive electrode external electrode 364 does not have a side sub-electrode extending to the third side 323 and the fourth side 324, and does not have the upper surface sub-electrode 361b in the laminated all-solid secondary battery 311 of the first embodiment.

The negative external electrode 374 has a cross-sectional shape of an L-shaped lower sub-electrode 374c extending to the lower surface 326. The end of the lower surface sub-electrode 374c (the lower end of the negative external electrode 374) is located at a position not facing the positive electrode 330 (the lower surface of the positive electrode 330). The negative electrode external electrode 374 does not have a side sub-electrode extending to the third side 323 and the fourth side 324, and does not have the upper surface sub-electrode 371b in the laminated all-solid secondary battery 311 of the first embodiment.

In the laminated all-solid secondary battery 314 of the present embodiment, as indicated by the arrow P, the occurrence of parasitic capacitance in the negative electrode 340 is suppressed to one portion between the positive external electrode 364 and the negative electrode 340. Further, as indicated by an arrow Q, the generation of the parasitic capacitance of the positive electrode 330 is suppressed to a portion between the negative external electrode 372 and the positive electrode 330. As described above, the laminated all-solid secondary battery 314 according to the present embodiment can suppress the occurrence of parasitic capacitance in the same manner as the laminated all-solid secondary battery 313 according to the third embodiment, and therefore, the pulse discharge cycle characteristics and the charge/discharge capacity can be further improved.

[ fifth embodiment ]

Next, a laminated all-solid secondary battery according to a fifth embodiment of the present invention will be described.

Fig. 9 is a schematic diagram of a laminated all-solid secondary battery according to a fifth embodiment, in which (a) is a top view seen from above, and (b) is a bottom view seen from below. Fig. 10 is a cross-sectional view taken along line X-X of fig. 9. In the description of the fifth embodiment, the same reference numerals are given to the constituent elements that overlap with those of the laminated all-solid secondary battery 311 of the first embodiment, and the description thereof will be omitted.

As shown in fig. 9 and 10, in the laminated all-solid secondary battery 315 according to the present embodiment, the positive external electrode 365 is provided on the first side surface 321 of the laminated body 320. A negative external electrode 375 is provided on the second side 322 of the stacked body 320.

The positive electrode external electrode 365 is an electrode having an I-shaped cross-sectional shape, does not have a side sub-electrode extending to the third side 323 and the fourth side 324, and does not have the upper surface sub-electrode 361b and the lower surface sub-electrode 361c in the stacked type all-solid secondary battery 311 of the first embodiment.

The negative electrode external electrode 375 is an electrode having an I-shaped cross-sectional shape, does not have a side sub-electrode extending to the third side 323 and the fourth side 324, and does not have the upper surface sub-electrode 371b and the lower surface sub-electrode 371c in the laminated all-solid secondary battery 311 of the first embodiment.

In the laminated all-solid secondary battery 315 according to the present embodiment, as indicated by an arrow P, a parasitic capacitance generation portion of the negative electrode 340 is suppressed to a portion between the positive electrode external electrode 365 and the negative electrode 340. In addition, as indicated by an arrow Q, a generation site of the parasitic capacitance of the positive electrode 330 is suppressed to one site between the negative external electrode 375 and the positive electrode 330. As described above, the laminated all-solid secondary battery 315 according to the present embodiment can suppress the occurrence of parasitic capacitance in the same manner as the laminated all-solid secondary battery 313 according to the third embodiment, and therefore, the pulse discharge cycle characteristics and the charge/discharge capacity can be further improved.

According to the laminated all-solid-state secondary batteries 311 to 315 of the present embodiment described above, the side end portions of the positive electrode external electrodes 361 to 365 are located at positions not facing the side end portion of the negative electrode 340, and the side end portions of the negative electrode external electrodes 371 to 375 are located at positions not facing the side end portion of the positive electrode 330, so that the occurrence of parasitic capacitance between the side end portions of the positive electrode external electrodes 361 to 365 and the negative electrode 340 and parasitic capacitance between the side end portions of the negative electrode external electrodes 371 to 375 and the positive electrode 330 can be suppressed. Therefore, the stacked all-solid secondary batteries 311 to 315 according to the present embodiment can improve the charge/discharge capacity and the pulse discharge cycle characteristics.

[ conventional laminated all-solid-state secondary battery ]

First, a conventional laminated all-solid secondary battery will be described.

Fig. 32 is a schematic diagram of a conventional laminated all-solid-state secondary battery, in which (a) is a plan view seen from above and (b) is a bottom view seen from below. Fig. 33 is a cross-sectional view taken along line XVIII-XVIII of fig. 32.

As shown in fig. 32 and 33, the laminated all-solid-state secondary battery 10 includes a laminated sintered body 20 obtained by sintering a laminate in which a positive electrode 30 and a negative electrode 40 are laminated with a solid electrolyte layer 50 interposed therebetween. The positive electrode 30 has a positive electrode collector layer 31 and a positive electrode active material layer 32. The anode 40 has an anode current collector layer 41 and an anode active material layer 42. The laminated sintered body 20 is a hexahedron, and has: 4 side surfaces (a first side surface 21, a second side surface 22, a third side surface 23, and a fourth side surface 24) formed as surfaces parallel to the stacking direction; and an upper surface 25 formed above and a lower surface 26 formed below as surfaces orthogonal to the stacking direction. The positive electrode collector layer is exposed on the first side surface 21, and the negative electrode collector layer is exposed on the second side surface 22. The third side surface 23 is a side surface on the right side when viewed from the first side surface 21 with the upper surface 25 facing upward, and the fourth side surface 24 is a side surface on the left side when viewed from the first side surface 21 with the upper surface 25 facing upward.

A positive electrode external electrode 60 electrically connected to the positive electrode current collector layer 31 is provided on the first side surface 21 of the laminated sintered body 20. The positive external electrode 60 includes: a lower surface sub-electrode 60a extending to the lower surface 26; an upper surface sub-electrode 60b extending to the upper surface 25; and a side sub-electrode 60c extending to the third side 23 and the fourth side 24. That is, the positive electrode external electrode 60 has a cross-sectional shape of コ font and 5 planes. The end of the lower surface sub-electrode 60a (the lower end of the positive electrode external electrode 60) is positioned to face the negative electrode 40 (the lower surface of the negative electrode 40). The end of the upper surface sub-electrode 60b (the upper end of the positive electrode external electrode 60) is positioned to face the negative electrode 40 (the upper surface of the negative electrode 40). The end of the side sub-electrode 60c (the end of the positive external electrode 60) is positioned to face the negative electrode 40 (the side of the negative electrode 40). Here, the facing position refers to a position where the lower surface sub-electrode 60a and the negative electrode 40 overlap each other in the case of the see-through laminated all-solid-state secondary battery 10, for example, in the case of the lower surface sub-electrode 60a and the negative electrode 40.

A negative electrode external electrode 70 electrically connected to the negative electrode current collector layer 41 is provided on the second side surface 22 of the laminated sintered body 20. The negative external electrode 70 has: a side sub-electrode 70c extending to the third side 23 and the fourth side 24; an upper surface sub-electrode 70b extending to the upper surface 25; and a lower surface sub-electrode 70a extending to the lower surface 26. That is, the negative electrode external electrode 70 has a cross-sectional shape of コ font and 5 faces. The end of the lower surface sub-electrode 70a (the lower end of the negative electrode external electrode 70) is positioned to face the positive electrode 30 (the lower surface of the positive electrode 30). The end of the upper surface sub-electrode 70b (the upper end of the negative electrode external electrode 70) is positioned to face the positive electrode 30 (the upper surface of the positive electrode 30). The end of the side sub-electrode 70c (the end of the negative external electrode 70) is positioned to face the positive electrode 30 (the side surface of the positive electrode 30).

In the laminated all-solid-state secondary battery 10, as indicated by the arrow P, the parasitic capacitance of the negative electrode 40 is generated in 4 places between the negative electrode 40 and the positive electrode external electrode 60, the lower surface sub-electrode 60a, and the side surface sub-electrode 60 c. As indicated by arrow Q, the sites of the positive electrode 30 where parasitic capacitance occurs are 4 sites between the negative external electrode 70, the lower surface sub-electrode 70a, and the side surface sub-electrode 70c, and the positive electrode 30. Therefore, in the laminated all-solid secondary battery 10, the charge/discharge capacity is easily reduced. In the laminated all-solid-state secondary battery 10, the positive electrode external electrode 60 and the negative electrode external electrode 70 are provided on the outer surface of the laminated sintered body 20, and therefore the volume is larger than that of the laminated sintered body 20, and the charge/discharge capacity per unit volume is reduced.

[ sixth embodiment ]

Next, a laminated all-solid secondary battery according to a sixth embodiment of the present invention will be described.

Fig. 13 is a schematic diagram of a laminated all-solid secondary battery according to a sixth embodiment, in which (a) is a top view and (b) is a bottom view. Fig. 14 is a sectional view taken along line II-II of fig. 13. In the description of the sixth embodiment, the same reference numerals are given to the constituent elements that overlap with those of the conventional laminated all-solid secondary battery 10, and the description thereof will be omitted.

As shown in fig. 13 and 14, in the laminated all-solid secondary battery 11 according to the present embodiment, the positive electrode external electrode 61 is provided on the first side surface 21 of the laminated sintered body 20. The positive electrode external electrode 61 is formed in the recess 21a provided on the first side surface 21. The negative electrode external electrode 71 is provided on the second side surface 22 of the laminated sintered body 20. The negative external electrode 71 is formed in the recess 22a provided on the second side surface 22.

The upper end of the positive electrode external electrode 61 (the end on the upper surface 25 side of the stacked sintered body 20) is in contact with the upper surface of the positive electrode 30. That is, the upper end of the positive electrode external electrode 61 is positioned inside (below) the upper end of the stacked sintered body 20 in the stacking direction so that the upper end of the positive electrode external electrode 61 does not face the negative electrode 40 (the upper surface of the negative electrode 40). Therefore, it is difficult to generate a parasitic capacitance between the upper end of the positive electrode external electrode 61 and the negative electrode 40. The upper end of the positive electrode external electrode 61 may be located in a range from a portion in contact with the upper surface of the positive electrode 30 to the upper end (upper surface 25) of the stacked sintered body 20 in the stacking direction.

The positive electrode external electrode 61 has a lower surface sub-electrode 61a extending to the lower surface 26 in order to facilitate connection with the circuit substrate. That is, the positive electrode external electrode 61 has an L-shaped cross section and has two faces. The positive electrode external electrode 61 does not include the upper surface sub-electrode 60b and the side surface sub-electrode 60c in the conventional stacked all-solid secondary battery 10. Further, if the end of the side sub-electrode is located at a position not facing the negative electrode 40, the positive electrode external electrode 61 may have a side sub-electrode. Here, the non-facing position is a position where the side sub-electrode and the negative electrode 40 do not overlap with each other in the case of the see-through laminated all-solid-state secondary battery 11.

The upper end of the negative external electrode 71 (the end on the upper surface 25 side of the stacked sintered body 20) is positioned in a portion in contact with the extension line of the upper surface of the positive electrode 30. That is, the upper end of the negative external electrode 71 is positioned inside the upper end of the stacked sintered body 20 in the stacking direction so that the upper end of the negative external electrode 71 does not face the upper surface of the positive electrode 30. Therefore, it is difficult to generate a parasitic capacitance between the upper end of the negative external electrode 71 and the positive electrode 30. The upper end of the negative external electrode 71 may be located in a range from a portion in contact with the extension line of the upper surface of the positive electrode 30 to the upper end of the stacked sintered body 20 in the stacking direction.

The negative external electrode 71 has a lower surface sub-electrode 71a extending to the lower surface 26 in order to facilitate connection to the circuit board. That is, the negative electrode external electrode 71 has an L-shaped cross section and has two surfaces. The negative external electrode 71 does not include the upper surface sub-electrode 70b and the side surface sub-electrode 70c in the laminated all-solid secondary battery 10. Further, if the end of the side sub-electrode is located at a position not facing the positive electrode 30, the negative electrode external electrode 71 may have a side sub-electrode.

In the laminated all-solid secondary battery 11 of the present embodiment, the occurrence of parasitic capacitance can be suppressed and the current consumption other than the charge-discharge reaction can be reduced as compared with the conventional laminated all-solid secondary battery 10, and therefore, the charge-discharge capacity is improved. In addition, since the generation of parasitic capacitance can be suppressed, the current distribution accompanying the charge and discharge reaction becomes uniform, and the battery reaction can be performed uniformly. As a result, the charge/discharge capacity is improved. In the stacked all-solid secondary battery 11 of the present embodiment, the positive electrode external electrode 61 and the negative electrode external electrode 71 are provided on the inner surface of the stacked sintered body 20, and therefore, the volume is smaller than that of the stacked all-solid secondary battery 10, and the charge/discharge capacity per unit volume is increased.

In the laminated all-solid secondary battery 11, the materials of the cathode current collector layer 31, the cathode active material layer 32, the anode current collector layer 41, the anode active material layer 42, the solid electrolyte layer 50, the cathode external electrode 61, and the anode external electrode 71 are not particularly limited, and known materials used in conventional laminated all-solid secondary batteries can be used.

As the material of the positive electrode collector layer 31 and the negative electrode collector layer 41, a material having high electrical conductivity is preferably used. Specifically, silver, palladium, gold, platinum, aluminum, copper, nickel, or the like can be used.

The positive electrode active material layer 32 and the negative electrode active material layer 42 contain a positive electrode active material and a negative electrode active material that can transfer electrons. In addition, a conductive aid, a binder, or the like may be contained. The positive electrode active material and the negative electrode active material are preferably capable of efficiently inserting and extracting lithium ions.

As the positive electrode active material and the negative electrode active material, for example, a transition metal oxide or a transition metal composite oxide is preferably used. Specifically, lithium manganese composite oxide Li may be used₂Mn_aMa_1-aO₃(0.8. ltoreq. a.ltoreq.1, Ma. Co, Ni), lithium cobaltate (LiCoO)₂) Lithium nickelate (LiNiO)₂) Lithium manganese spinel (LiMn)₂O₄) The general formula is as follows: LiNi_xCo_yMn_zO₂A complex metal oxide represented by (x + y + z ≦ 1, 0. ltoreq. x.ltoreq.1, 0. ltoreq. y.ltoreq.1, 0. ltoreq. z.ltoreq.1), and a lithium vanadium compound (LiV)₂O₅) Olivine type LiMbPO₄(where Mb is 1 or more elements selected from the group consisting of Co, Ni, Mn, Fe, Mg, Nb, Ti, Al and Zr), lithium vanadium phosphate (Li)₃V₂(PO₄)₃Or LiVOPO₄) From Li₂MnO₃-LiMcO₂Li-excess solid solution represented by (Mc ═ Mn, Co, and Ni), and lithium titanate (Li)₄Ti₅O₁₂) From Li_sNi_tCo_uAl_vO₂And (0.9 < s < 1.3, 0.9 < t + u + v < 1.1).

The positive electrode active material and the negative electrode active material may be selected according to a solid electrolyte described later. For example, in the use of Li_1+nAl_nTi_2-n(PO₄)₃(0. ltoreq. n. ltoreq.0.6) As the solid electrolyte, LiVOPO is preferably used as the positive electrode active material and the negative electrode active material₄And Li₃V₂(PO₄)₃One or both of them. The interface between the positive electrode active material layer 32 and the negative electrode active material layer 42 and the solid electrolyte layer 50 is strongly bonded. In addition, the positive electrode active material layer 32 and the negative electrode active material layer 42 can be made to be solid electrolyteThe contact area of the interface of the layer 50 becomes large.

The solid electrolyte layer 50 contains a solid electrolyte. As the solid electrolyte, a material having low electron conductivity and high lithium ion conductivity is preferably used. Specifically, for example, it is preferably selected from La_0.51Li_0.34TiO_2.94And La_0.5Li_0.5TiO₃Isoperovskite compound, Li₁₄Zn(GeO₄)₄Isolithium Super Ion Conductor (LISICON) type compound, and Li₇La₃Zr₂O₁₂Isogarnet-type compound, LiZr₂(PO₄)₃、Li_1.3Al_0.3Ti_1.7(PO₄)₃And Li_1.5Al_0.5Ge_1.5(PO₄)₃Sodium Isoionic Conductor (NASICON) type compound and Li_3.25Ge_0.25P_0.75S₄And Li₃PS₄Isothiolithium super ion conductor (Thio-lithium) type compound, 50Li₄SiO₄·50Li₃BO₃、Li₂S-P₂S₅And Li₂O-Li₃O₅-SiO₂Isoglass compound, Li₃PO₄、Li_3.5Si_0.5P_0.5O₄And Li_2.9PO_3.3N_0.46Isophosphoric acid compound, Li_2.9PO_3.3N_0.46(LIPON) and Li_3.6Si_0.6P_0.4O₄Iso-amorphous, Li_1.07Al_0.69Ti_1.46(PO₄)₃And Li_1.5Al_0.5Ge_1.5(PO₄)₃And so on, and at least 1 of the glass-ceramics.

As the material of the positive electrode external electrode 61 and the negative electrode external electrode 71, a conductive material having high conductivity is preferably used. As the conductive material, for example, silver, gold, platinum, aluminum, copper, tin, nickel can be used.

Next, a method for manufacturing the laminated all-solid secondary battery 11 according to the present embodiment will be described with reference to fig. 15 to 20. Fig. 15 is a flowchart of the method for manufacturing the laminated all-solid secondary battery according to the present embodiment. Fig. 16 is a schematic diagram of a cell laminate used in the method for manufacturing a laminated all-solid secondary battery according to the present embodiment, where (a) is a plan view and (b) is a sectional view taken along line IVb-IVb of (a). Fig. 17 is a schematic view showing a state in which a groove is provided in the cell laminate of fig. 16, wherein (a) is a plan view, and (b) is a cross-sectional view taken along the line Vb-Vb of (a).

Fig. 18 is a cross-sectional view showing a state in which the grooves of the cell laminate of fig. 17 are filled with electrodes.

Fig. 19 is a cross-sectional view showing a state in which the sub-electrode is connected to the electrode of the cell laminate of fig. 18. Fig. 20 is a cross-sectional view showing a state where the cell laminate is cut.

As shown in fig. 15, the method for manufacturing the laminated all-solid-state secondary battery 11 according to the present embodiment includes a cell laminate manufacturing step S01, a groove forming step S02, a conductive material filling step S03, a sub-electrode forming step S04, a cutting step S05, and a firing step S06.

In the cell laminate forming step S01, the cell laminate 120 shown in fig. 16 is formed. The cell laminate 120 is a laminate in which a solid electrolyte layer 150a, a negative electrode cell 145, a solid electrolyte layer 150b, a positive electrode cell 135, and a solid electrolyte layer 150c are laminated in this order from the lower surface 126 side. The cell stack 120 is a hexahedron, and includes: 4 side surfaces (a first side surface 121, a second side surface 122, a third side surface 123, and a fourth side surface 124) formed as surfaces parallel to the stacking direction; and an upper surface 125 formed above and a lower surface 126 formed below as surfaces orthogonal to the stacking direction. The positive electrode unit 135 is formed by arranging two or more positive electrodes 130 having the positive electrode collector layer 131 and the positive electrode active material layer 132 with a spacer 133 in the surface direction of the positive electrode 130. The negative electrode unit 145 is formed by arranging two or more negative electrodes 140 having a negative electrode collector layer 141 and a negative electrode active material layer 142 along the surface direction of the negative electrode 140 with a spacer 143 therebetween. The cell stack 120 is stacked such that the spacer 133 of the positive electrode cell 135 faces the negative electrode 140 of the negative electrode cell 145, and the spacer 143 of the negative electrode cell 145 faces the positive electrode 130 of the positive electrode cell 135. The cell laminate 120 has solid electrolyte layers 150a and 150c on both the upper and lower surfaces in the lamination direction, respectively.

The cell laminate 120 can be produced, for example, by a method including the following steps: a paste preparation step of preparing a paste for each member constituting the cell laminate 120; a cell preparation step of preparing the positive electrode cell 135 and the negative electrode cell 145 using the prepared paste; and a lamination step of alternately laminating the obtained positive electrode cell 135 and negative electrode cell 145 to produce a laminated structure.

< preparation Process of paste >

In the paste preparation step, the respective members of the positive electrode collector layer, the positive electrode active material layer, the solid electrolyte layer, the negative electrode collector layer, the negative electrode active material layer, and the external electrode are pasted. The method of making the paste is not particularly limited, and for example, the paste can be prepared by mixing the powders of the above-mentioned respective members and a vehicle. As a mixing device for producing the paste, a conventionally known mixing device such as a bead mill, a planetary paste mixer, an automatic attritor, a three-roll mill, a high shear mixer, a planetary mixer, or the like can be used. Here, the vehicle is a generic term for a medium in a liquid phase, and includes a solvent, a binder, and the like. The binder contained in the paste of each member is not particularly limited, and a polyvinyl acetal resin, a polyvinyl butyral resin, a terpineol resin, an ethyl cellulose resin, an acrylic resin, a polyurethane resin, a vinyl acetate resin, a polyvinyl alcohol resin, or the like can be used. These resins may be used alone in 1 kind, or 2 or more kinds may be used in combination.

In addition, the paste of each material may contain a plasticizer. The type of plasticizer is not particularly limited, and phthalic acid esters such as dioctyl phthalate and diisononyl phthalate can be used.

By the above-described method, a paste for a positive electrode collector layer, a paste for a positive electrode active material layer, a paste for a solid electrolyte layer, a paste for a negative electrode active material layer, and a paste for a negative electrode collector layer were prepared.

< Process for producing cell >

The positive electrode unit 135 may be fabricated as follows.

First, the prepared paste for a solid electrolyte layer is applied to a substrate such as a polyethylene terephthalate (PET) film to a desired thickness and dried to prepare a green sheet for a solid electrolyte layer. The method of applying the paste for the solid electrolyte layer is not particularly limited, and known methods such as a doctor blade method, a die coating method, a comma coating method, and a gravure coating method can be used. Next, on the solid electrolyte layer green sheet, a positive electrode active material layer paste, a positive electrode collector layer paste, and a positive electrode active material layer paste are sequentially printed by screen printing and dried, thereby forming a positive electrode 130 in which a positive electrode active material layer 132, a positive electrode collector layer 131, and a positive electrode active material layer 132 are sequentially stacked. Further, in order to fill the difference in height between the solid electrolyte layer green sheet and the positive electrode, a solid electrolyte layer paste is printed on a region (edge) other than the positive electrode by a screen printing method and dried, thereby forming a solid electrolyte layer having the same height as the positive electrode. Then, the substrate is peeled off, whereby a positive electrode unit 135 having the positive electrode 130 formed on the solid electrolyte layer green sheet is obtained.

The negative electrode cell 145 can be produced in the same manner as the above-described method for producing a positive electrode cell, except that a paste for a negative electrode active material layer and a paste for a negative electrode current collector layer are used instead of the paste for a positive electrode current collector layer and the paste for a positive electrode active material layer.

< laminating Process >

In the stacking step, the positive electrode cells and the negative electrode cells are alternately stacked. In this way, a stacked structure including a plurality of positive electrode cells and negative electrode cells is produced.

Then, the produced laminated structure is collectively pressed and bonded by a die press, a Warm Isostatic Press (WIP), a Cold Isostatic Press (CIP), a hydrostatic press, or the like, and the adhesion between the positive electrode unit and the negative electrode unit can be improved. The pressurization is preferably carried out simultaneously with the heating, and may be carried out at 40 to 95 ℃.

Next, in the groove forming step S02, as shown in fig. 17, the first groove 161 for cutting the negative electrode 140 through the spacer 133 of the positive electrode cell 135 and the second groove 162 for cutting the positive electrode 130 through the spacer 143 of the negative electrode cell 145 are formed along the stacking direction of the cell laminate 120 from the lower surface 126 side.

The depth of the first and second grooves 161 and 162 is preferably the same. Although the depths of the first groove 161 and the second groove 162 are depths up to the interface where the solid electrolyte layer 150c on the upper surface 125 side and the positive electrode unit 135 contact each other in fig. 17, the depths may be greater than the interface.

As a method of forming the grooves in the cell stack 120, a dicing saw device or a fine laser processing machine may be used.

In the conductive material filling step S03, as shown in fig. 18, the conductive material 163 is filled in the first groove 161 and the second groove 162. As a method of filling the conductive material into the first and second grooves 161 and 162, the following method may be used: paste of a conductive material is filled in the first groove 161 and the second groove 162 by screen printing, and then the paste of a conductive material is heated and dried.

In the sub-electrode forming step S04, as shown in fig. 19, the sub-electrode 164 electrically connected to the conductive material 163 is formed on the surface of the lower surface of the cell laminate 120. The material of the sub-electrode 164 is preferably the same as the material of the conductive material 163.

As a method of forming the sub-electrode 164, a method of applying a paste of a conductive material and then drying the paste of the conductive material by heating may be used.

In the cutting step S05, as shown in fig. 20, a notch 165 penetrating the cell laminate 120 is formed in the first groove 161 filled with the conductive material 163 and the second groove 162 filled with the conductive material 163, and the cell laminate 120 is cut in the lamination direction. Thereby, a unit laminate sheet (unfired laminated all-solid secondary battery 11) was obtained.

As a method of forming the slit 165 in the cell laminate 120, a dicing blade or a fine laser machine may be used.

In the firing step S06, the unit laminate sheet is fired and sintered to produce the laminated all-solid secondary battery 11. The firing conditions are, for example, a temperature of 600 ℃ to 1000 ℃ in a nitrogen atmosphere. The firing time is, for example, in the range of 0.1 hour to 3 hours. In the case of a reducing atmosphere, firing may be performed in, for example, an argon atmosphere or a mixed nitrogen-hydrogen atmosphere instead of a nitrogen atmosphere.

Before the firing step, binder removal treatment may be performed as a step different from the firing step. By thermally decomposing the binder component contained in the unit laminate sheet before firing, rapid decomposition of the binder component in the firing step can be suppressed. The binder removal treatment is performed, for example, at a temperature in the range of 300 to 800 ℃ for 0.1 to 10 hours in a nitrogen atmosphere. In the case of a reducing atmosphere, the binder removal treatment may be performed in an argon atmosphere or a mixed nitrogen-hydrogen atmosphere instead of a nitrogen atmosphere.

[ seventh embodiment ]

Next, a laminated all-solid secondary battery 12 according to a seventh embodiment of the present invention will be described.

Fig. 26 is a sectional view of the laminated all-solid secondary battery according to the seventh embodiment, in which (a) is a top view and (b) is a bottom view. Fig. 27 is a sectional view taken along line II-II of the laminated all-solid secondary battery according to the seventh embodiment. In the description of the seventh embodiment, the same reference numerals are given to the constituent elements that overlap with the laminated all-solid secondary battery 11 of the sixth embodiment, and the description thereof will be omitted.

As shown in fig. 27, in the laminated all-solid secondary battery 12 of the present embodiment, the positive electrode external electrode 62 is provided on the first side surface 21 of the laminated sintered body 20, and the negative electrode external electrode 72 is provided on the second side surface 22. The positive electrode external electrode 62 and the negative electrode external electrode 72 each have a lower surface sub-electrode 62a and a lower surface sub-electrode 72a, and have an L-shaped cross section, which is similar to the laminated all-solid secondary battery 11 according to the sixth embodiment. On the other hand, the laminated all-solid secondary battery 12 of the present embodiment is different from the laminated all-solid secondary battery 11 of the sixth embodiment in that the lower surface sub-electrode 62a and the lower surface sub-electrode 72a are embedded in the lower surface 26 of the laminated sintered body 20.

In the laminated all-solid secondary battery 12 of the present embodiment, the lower surface sub-electrode 62a of the positive electrode external electrode 62 and the lower surface sub-electrode 72a of the negative electrode external electrode 72 are embedded in the lower surface 26 of the laminated sintered body 20, and therefore, the volume is smaller than that of the laminated all-solid secondary battery 11 of the sixth embodiment. Therefore, the volumetric energy density of the laminated all-solid secondary battery 13 of the present embodiment is improved.

[ eighth embodiment ]

Next, a laminated all-solid secondary battery 13 according to an eighth embodiment of the present invention will be described.

Fig. 28 is a sectional view of the laminated all-solid secondary battery according to the eighth embodiment, in which (a) is a top view seen from above, and (b) is a bottom view seen from below. Fig. 29 is a sectional view taken along line II-II of the laminated all-solid secondary battery according to the eighth embodiment. In the description of the eighth embodiment, the same reference numerals are given to the constituent elements that overlap with the laminated all-solid secondary battery 11 of the sixth embodiment, and the description thereof will be omitted.

As shown in fig. 29, the laminated all-solid secondary battery 13 according to the present embodiment is different from the laminated all-solid secondary battery 11 according to the sixth embodiment in that the positive electrode external electrode 63 and the negative electrode external electrode 73 do not have lower surface sub-electrodes.

In the laminated all-solid secondary battery 13 of the present embodiment, it is difficult to generate a parasitic capacitance between the lower surface sub-electrode 61a of the positive electrode external electrode 63 and the lower surface of the negative electrode 40. In addition, it is difficult to generate a parasitic capacitance between the lower surface sub-electrode 71a of the negative external electrode 71 and the lower surface of the positive electrode 30. Therefore, the charge/discharge capacity of the laminated all-solid secondary battery 13 of the present embodiment is improved.

[ ninth embodiment ]

Next, a laminated all-solid secondary battery 14 according to a ninth embodiment of the present invention will be described.

Fig. 30 is a sectional view of the laminated all-solid secondary battery according to the ninth embodiment, in which (a) is a top view and (b) is a bottom view. Fig. 31 is a sectional view taken along line II-II of the laminated all-solid secondary battery according to the ninth embodiment. In the description of the ninth embodiment, the same reference numerals are given to the constituent elements that overlap with the laminated all-solid secondary battery 11 of the sixth embodiment, and the description thereof will be omitted.

As shown in fig. 31, the laminated all-solid secondary battery 14 according to the present embodiment is different from the laminated all-solid secondary battery 11 according to the sixth embodiment in that the lower end of the positive electrode external electrode 64 is positioned in a portion in contact with an extension line of the lower surface of the negative electrode 40, the lower end of the negative electrode external electrode 74 is in contact with the lower surface of the negative electrode 40, and the lower ends of the positive electrode external electrode 64 and the negative electrode external electrode 74 are not exposed to the lower surface of the laminated all-solid secondary battery 14.

In the laminated all-solid secondary battery 14 of the present embodiment, it is difficult to generate a parasitic capacitance between the lower portion of the negative electrode external electrode 74 and the positive electrode 30. As described above, the laminated all-solid secondary battery 14 according to the present embodiment can further suppress the occurrence of parasitic capacitance and further improve the charge/discharge capacity, as compared with the laminated all-solid secondary battery 11 according to the sixth embodiment.

Next, a method for manufacturing the laminated all-solid secondary battery 14 according to the ninth embodiment will be described. The method for manufacturing the laminated all-solid secondary battery 14 according to the present embodiment includes a cell laminate manufacturing step S11, a groove forming step S12, a conductive material filling step S13, a solid electrolyte layer forming step S14, a cutting step S15, and a firing step S16.

In the cell laminate producing step S11, the cell laminate 220 shown in fig. 21 is produced. The cell laminate 220 is a laminate in which the solid electrolyte layer 150a, the positive electrode cell 135, the solid electrolyte layer 150b, and the negative electrode cell 145 are laminated in this order from the lower surface 226 side. The cell stack 220 is a hexahedron, and has: 4 side surfaces formed as surfaces parallel to the stacking direction; and an upper surface 225 formed above and a lower surface 226 formed below, which are surfaces orthogonal to the stacking direction. The positive electrode unit 235 is formed by arranging two or more positive electrodes 230 having a positive electrode collector layer 231 and a positive electrode active material layer 232 along the surface direction of the positive electrode 130 with a spacer 233 therebetween. The negative electrode unit 245 is formed by arranging two or more negative electrodes 140 having the negative electrode collector layer 241 and the negative electrode active material layer 242 along the surface direction of the negative electrode 240 with the spacing section 143 interposed therebetween. The cell laminate 220 is laminated such that the separator 233 of the positive electrode cell 235 faces the negative electrode 240 of the negative electrode cell 245, and the separator 133 of the negative electrode cell 145 faces the positive electrode 130 of the positive electrode cell 135. The cell laminate 220 has a solid electrolyte layer 250a on a lower surface (lower surface 226) in the lamination direction.

Next, in the groove forming step S12, as shown in fig. 22, from the surface (upper surface 225) opposite to the surface having the solid electrolyte layer 250a, a first groove 261 for cutting the negative electrode 140 through the spacer 233 of the positive electrode cell 235 and a second groove 262 for cutting the positive electrode 130 through the spacer 243 of the negative electrode cell 245 are formed along the stacking direction of the cell laminate 120.

Preferably, the first grooves 261 and the second grooves 262 have the same depth. The depth of the first groove 261 and the second groove 262 is the depth up to the interface between the solid electrolyte layer 250a on the lower surface 226 side and the negative electrode cell 245 in fig. 17, but may be a depth exceeding the interface.

In the conductive material filling step S13, as shown in fig. 23, the conductive material 263 is filled in the first groove 261 and the second groove 262.

In the solid electrolyte layer forming step S14, as shown in fig. 24, the solid electrolyte layer 250c is formed on the surface of the upper surface of the cell laminate 220. The material of the solid electrolyte layer 250c is preferably the same as the material of the solid electrolyte layers 250a and 250 b.

As a method for forming the solid electrolyte layer 250c, a method of applying a paste of a solid electrolyte and then drying the paste of the solid electrolyte by heating may be used.

In the cutting step S15, as shown in fig. 25, the slit 165 penetrating the cell laminate 220 is formed in the first groove 261 filled with the conductive material 263 and the second groove 262 filled with the conductive material 263, and the cell laminate 220 is cut in the lamination direction. Thereby, a unit laminate sheet (unfired laminated all-solid secondary battery 14) was obtained.

In the firing step S16, the unit laminate sheet is fired and sintered to produce the laminated all-solid secondary battery 14.

According to the laminated all-solid secondary batteries 11 to 14 of the sixth to ninth embodiments described above, the positive electrode external electrodes 61, 62, 64 are positioned inside (below) the upper end portion in the laminating direction of the laminated sintered body 20, and therefore the positive electrode external electrodes 61, 62, 63, 64 can avoid the parasitic capacitance generated between the upper surface sub-electrode 70b of the negative electrode external electrode 70 and the positive electrode 30 in the conventional laminated all-solid secondary battery 10 shown in fig. 33. Similarly, in the conventional stacked all-solid-state secondary battery 10 shown in fig. 33, the negative external electrodes 71, 72, 73, and 74 can avoid the parasitic capacitance generated between the lower sub-electrode 60a of the positive external electrode 60 and the negative electrode 40.

In addition, according to the laminated all-solid-state secondary batteries of embodiments 6 to 9, by firing the unfired laminated all-solid-state battery in which the negative electrode external electrode and the negative electrode current collector are well bonded to each other, good bonding properties can be obtained even after firing the positive electrode external electrode and the positive electrode current collector, and the negative electrode external electrode and the negative electrode current collector, and the cycle characteristics are improved as compared with those of the conventional laminated all-solid-state secondary batteries.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the constituent elements and combinations thereof in the embodiments are merely examples, and additions, omissions, substitutions, and other modifications of the constituent elements can be made without departing from the spirit of the present invention.

For example, in the laminated all-solid secondary batteries 311 to 315 according to the first to fifth embodiments, the number of the positive electrodes 330 and the negative electrodes 340 is not particularly limited, and a plurality of positive electrodes 330 and a plurality of negative electrodes 340 may be alternately laminated. When a plurality of positive electrodes 330 and negative electrodes 340 are stacked, the tip of the secondary electrode of the positive electrode external electrode is preferably located at a position not opposed to the main surface of the negative electrode stacked at the position closest to the secondary electrode in the stacking direction. Preferably, the tip end portion of the sub-electrode of the negative external electrode is located at a position not opposed to the main surface of the positive electrode laminated at a position closest to the sub-electrode in the laminating direction. This can suppress the occurrence of parasitic capacitance between the sub-electrode of the positive external electrode and the negative electrode and parasitic capacitance between the sub-electrode of the negative external electrode and the positive electrode.

In the laminated all-solid-state secondary batteries 11 to 14 according to the sixth to ninth embodiments, the number of the positive electrodes 30 and the negative electrodes 40 is not particularly limited, and a plurality of positive electrodes 30 and a plurality of negative electrodes 40 may be alternately laminated.

In the laminated all-solid secondary batteries 11 to 14 according to the sixth to ninth embodiments, the upper end portions of the positive electrode external electrodes 61, 62, 64 and the negative electrode external electrodes 71, 72, 74 (the end portions on the upper surface 25 side of the laminated sintered body 20) are positioned inside (below) the upper end portions of the laminated sintered body 20 in the laminating direction, but the present invention is not limited thereto. The lower end portions of the positive electrode external electrodes 61, 62, 64 and the negative electrode external electrodes 71, 72, 74 (the end portions on the lower surface 26 side of the stacked sintered body 20) may be positioned inward (upward) of the lower end portions of the stacked sintered body 20 in the stacking direction.

Examples

The present invention will be described in more detail below with reference to the above-described embodiments and comparative examples, but the present invention is not limited to these examples. The term "part" of the material to be charged in the preparation of the paste means "part by mass" unless otherwise specified.

[ example 1]

< preparation Process of paste >

(preparation of paste for solid electrolyte layer)

As the solid electrolyte powder, Li was used_1.3Al_0.3Ti_1.7(PO₄)₃And (3) powder. Li_1.3Al_0.3Ti_1.7(PO₄)₃The powder was prepared by the following method.

First, Li is added₂CO₃Powder, Al₂O₃Powder, TiO₂Powder and NH₄H₂PO₄The powder was wet-mixed with a ball mill as a starting material, and then dehydrated and dried to obtain a powder mixture. Next, the obtained powder mixture is provisionally fired in the atmosphere to obtain provisionally fired powder. The obtained calcined powder was subjected to wet pulverization by a ball mill to obtain Li_1.3Al_0.3Ti_1.7(PO₄)₃And (3) powder.

With respect to the above Li_1.3Al_0.3Ti_1.7(PO₄)₃100 parts of the powder was wet-mixed by a ball mill with 100 parts of ethanol and 200 parts of toluene as solvents added. Then, 16 parts of a binder and 4.8 parts of benzylbutyl phthalate were further added and wet-mixed to prepare a paste for a solid electrolyte layer.

(preparation of paste for Positive electrode active Material layer and paste for negative electrode active Material layer)

Li was used as the positive electrode active material powder and the negative electrode active material powder₃V₂(PO₄)₃And (3) powder. Li₃V₂(PO₄)₃The powder was prepared by the following method.

First, Li is added₂CO₃Powder, V₂O₅Powder and NH₄H₂PO₄As a starting material, wet mixing was performed using a ball mill, and then dehydration and drying were performed to obtain a powder mixture. Subsequently, the obtained powder mixture was subjected to provisional firing at 850 ℃ to obtain a provisionally fired powder. The obtained calcined powder was subjected to wet pulverization by a ball mill to obtain Li₃V₂(PO₄)₃And (3) powder.

With respect to the above Li₃V₂(PO₄)₃100 parts of the powder was mixed with 15 parts of a binder and 65 parts of dihydroterpineol as a solvent, and the mixture was dispersed to prepare a positive electrode active material layer paste and a negative electrode active material layer paste.

(preparation of paste for Positive electrode collector layer and paste for negative electrode collector layer)

As materials for the positive electrode collector layer and the negative electrode collector layer, 10 parts of a binder and 50 parts of dihydroterpineol as a solvent were added to 100 parts of Cu powder and mixed and dispersed to prepare a paste for the positive electrode collector layer and a paste for the negative electrode collector layer.

(preparation of conductive paste for external electrode)

20 parts of dihydroterpineol as a solvent was added to 100 parts of Cu powder, and mixed and dispersed to prepare a conductive material paste for external electrodes.

Using these pastes, a laminated all-solid secondary battery was produced as follows.

(preparation of Positive electrode Unit)

A solid electrolyte layer paste was applied to a PET film as a substrate by a doctor blade method and dried to form a solid electrolyte layer green sheet. Next, a paste for a positive electrode active material layer, a paste for a positive electrode collector layer, and a paste for a positive electrode active material layer are sequentially printed on the green sheet for a solid electrolyte layer by a screen printing method, thereby forming a green sheet for a positive electrode in which a positive electrode active material layer, a positive electrode collector layer, and a positive electrode active material layer are sequentially stacked. Next, a solid electrolyte layer having a height substantially flush with the positive electrode is formed on the edge other than the positive electrode by a screen printing method using a paste for a solid electrolyte layer, and dried. Then, the obtained laminate was peeled from the PET film to produce a positive electrode unit.

(preparation of negative electrode Unit)

A negative electrode cell was produced in the same manner as the above-described method for producing a positive electrode cell, except that the paste for a negative electrode active material layer and the paste for a negative electrode current collector layer were used instead of the paste for a positive electrode current collector layer and the paste for a positive electrode active material layer.

< laminating Process >

The positive electrode unit and the negative electrode unit are alternately stacked in plurality. Next, a plurality of solid electrolyte layer green sheets were stacked on both principal surfaces of the obtained laminate to obtain a laminate structure. The obtained laminated structure was thermocompression bonded using a press.

The solid electrolyte layer green sheet was produced by applying a solid electrolyte layer paste onto a PET film by a doctor blade method and drying the paste.

< cutting step and firing step >

The obtained laminated structure was cut so that the positive electrode collector layer was exposed from one end face and the negative electrode collector layer was exposed from the end face opposite to the one end face. Subsequently, the cut laminate structure was fired at 800 ℃ for 1 hour to obtain a laminate 320. The dimensions of the obtained laminate 320 were 5.5mm in length, 4.0mm in width and 1.0mm in thickness.

< external electrode Forming Process >

The entire surfaces of the first side surface 321 and the second side surface 322 of the laminate 320 obtained in the firing step, the range of 1mm from the end on the first side surface 321 side and the range of 1mm from the end on the second side surface 322 side of the upper surface 325, and the range of 1mm from the end on the first side surface 321 side and the range of 1mm from the end on the second side surface 322 side of the lower surface 326 were coated with the conductive Cu paste for external electrodes by the screen printing method, and the firing treatment was performed at 500 ℃. Further, the conductive Cu paste for external electrodes is not applied to the third side 323 and the fourth side 324 of the laminate 320. In this way, the laminated all-solid secondary battery 311 according to the first embodiment, which has the upper surface sub-electrodes 361b and 371b and the lower surface sub-electrodes 361c and 371c and in which the cross-sectional shapes of the positive electrode external electrode 361 and the negative electrode external electrode 371 are コ shapes, was produced.

[ example 2]

A laminated all-solid secondary battery 312 according to the second embodiment was fabricated in the same manner as in example 1, except that the conductive Cu paste for external electrodes was not applied to the upper surface 325 of the laminate 320, and the cross-sectional shapes of the positive external electrode 362 and the negative external electrode 372 were L-shaped.

[ example 3]

A laminated all-solid secondary battery 313 according to the third embodiment was fabricated in the same manner as in example 1, except that the application range of the conductive Cu paste for external electrodes on the upper surface 325 of the laminate 320 was set to a range of 0.4mm from the end on the first side surface 321 side and a range of 0.4mm from the end on the second side surface 322 side, and the application range of the conductive Cu paste for external electrodes on the lower surface 326 of the laminate 320 was set to a range of 0.4mm from the end on the first side surface 321 side and a range of 0.4mm from the end on the second side surface 322 side, so that the cross-sectional shapes of the positive external electrode 363 and the negative external electrode 373 were コ shapes.

[ example 4]

A laminated all-solid secondary battery 314 according to the fourth embodiment in which the sectional shapes of the positive electrode external electrode 364 and the negative electrode external electrode 374 are L-shaped was produced in the same manner as in example 1, except that the conductive Cu paste for external electrodes was not applied to the upper surface 325 of the laminate 320, and the application range of the conductive Cu paste for external electrodes to the lower surface 326 of the laminate 320 was set to the range of 0.4mm from the end on the first side surface 321 side and the range of 0.4mm from the end on the second side surface 322 side.

[ example 5]

A laminated all-solid secondary battery 315 of a fifth embodiment in which the cross-sectional shapes of the positive electrode external electrode 365 and the negative electrode external electrode 375 are I-shaped was produced in the same manner as in example 1, except that the conductive Cu paste for external electrodes was not applied to the upper surface 325 and the lower surface 326 of the laminated body 320.

Comparative example 1

A conventional stacked type all-solid secondary battery 310 shown in fig. 11 and 12 was produced in the same manner as in example 1, except that conductive Cu paste for external electrodes was applied by a dip coating method and dried in a range of 1mm from the end on the first side 321 side and a range of 1mm from the end on the second side 322 side of the third side 323 and the fourth side 324 of the stacked body 320, and that side sub-electrodes 360a and 370a were formed on the third side 323 and the fourth side 324 of the stacked body 320.

[ evaluation ]

The first charge/discharge capacity, the pulse discharge cycle characteristics, the charge/discharge cycle characteristics, and the mounting shear strength of the laminated all-solid secondary batteries manufactured in examples 1 to 5 and comparative example 1 were measured by the following methods. The results are shown in table 1 below together with the structures of the positive and negative external electrodes and the number of electrode surfaces.

< initial charge-discharge capacity >

The measurement of the initial charge-discharge capacity was performed in an environment of 25 ℃. The charging capacity was a capacity measured when the battery voltage became 1.6V and was held at a constant current of 0.1C for 3 hours. The discharge capacity is a capacity measured after charging and discharging at a constant current of 0.2C until the battery voltage becomes 0V. The first discharge capacity (initial discharge capacity) is shown in table 1. The discharge capacity is a relative value when the discharge capacity of the laminated all-solid secondary battery produced in comparative example 1 is taken as 100.

< pulsed discharge cycle characteristics >

In the pulse discharge cycle characteristics, charging was performed under the same charging conditions as those for the first measurement of the charge/discharge capacity in an environment of 25 ℃, then, discharging was performed at a large current of 20C for 1 second, and the operation was stopped for 59 seconds, and the number of pulse discharge cycles was measured by repeating the operation until the battery voltage became 1.2V.

< Charge-discharge cycle characteristics >

The measurement of the initial charge/discharge capacity described above was performed as 1 cycle, and the charge/discharge capacity retention rate after repeating the cycle for 1000 cycles was evaluated as the charge/discharge cycle characteristic. The charge-discharge cycle characteristics in the present embodiment are calculated by the following calculation formula.

Charge-discharge capacity maintenance rate after 1000 cycles [% ] (discharge capacity after 1000 cycles ÷ initial discharge capacity) × 100

< installation shear Strength >

The laminated all-solid-state secondary batteries fabricated in examples and comparative examples were mounted on a pad electrode on a glass epoxy substrate, and mounted on the glass epoxy substrate by reflow soldering. The mounted laminated all-solid secondary battery was subjected to a mounting shear strength measurement by activating a load cell at a rate of 0.15 mm/sec from the side surface of the laminated all-solid secondary battery using a shear strength tester, applying a stress from the front side surface, peeling the laminated all-solid secondary battery from the glass epoxy substrate, and measuring the stress applied when the laminated all-solid secondary battery was peeled from the glass epoxy substrate.

[ Table 1]

The laminated all-solid secondary batteries of examples 1 to 5, in which the side end portions (side sub-electrodes 361a to 365a) of the positive electrode external electrodes 361 to 365 were located at positions not facing the side end portion of the negative electrode 340, and the side end portions (side sub-electrodes 371a to 375a) of the negative electrode external electrodes 371 to 375 were located at positions not facing the side end portion of the positive electrode 330, were improved in the initial charge-discharge capacity, the pulse discharge cycle characteristic, and the charge-discharge cycle characteristic, compared to the laminated all-solid secondary battery of comparative example 1.

In particular, the laminated all-solid-state secondary batteries of examples 3 to 5, in which the upper and lower ends of the positive electrode external electrodes 363 to 365 were located at positions not facing the negative electrode 340 and the upper and lower ends of the negative electrode external electrodes 373 to 375 were located at positions not facing the positive electrode 330, were improved in the initial charge/discharge capacity, the pulse discharge cycle characteristics, and the charge/discharge cycle characteristics. However, the mounting shear strength of the laminated all-solid secondary battery of example 5, which did not have the upper surface sub-electrode and the lower surface sub-electrode, was reduced.

[ example 6]

< preparation Process of paste >

(preparation of paste for solid electrolyte layer)

As the solid electrolyte powder, Li was used_1.3Al_0.3Ti_1.7(PO₄)₃And (3) powder. Li_1.3Al_0.3Ti_1.7(PO₄)₃The powder was prepared by the following method.

First, Li is added₂CO₃Powder, Al₂O₃Powder, TiO₂Powder and NH₄H₂PO₄The powder was wet-mixed with a ball mill as a starting material, and then dehydrated and dried to obtain a powder mixture. Next, the obtained powder mixture is provisionally fired in the atmosphere to obtain provisionally fired powder. The obtained calcined powder was subjected to wet pulverization by a ball mill to obtain Li_1.3Al_0.3Ti_1.7(PO₄)₃And (3) powder.

With respect to the above Li_1.3Al_0.3Ti_1.7(PO₄)₃100 parts of the powder was wet-mixed by a ball mill with 100 parts of ethanol and 200 parts of toluene as solvents added. Then, 16 parts of a binder and 4.8 parts of benzylbutyl phthalate were further added and wet-mixed to prepare a paste for a solid electrolyte layer.

(preparation of paste for Positive electrode active Material layer and paste for negative electrode active Material layer)

Li was used as the positive electrode active material powder and the negative electrode active material powder₃V₂(PO₄)₃And (3) powder.

Li₃V₂(PO₄)₃The powder was prepared by the following method.

First, Li is added₂CO₃Powder, V₂O₅Powder and NH₄H₂PO₄As a starting material, wet mixing was performed using a ball mill, and then dehydration and drying were performed to obtain a powder mixture. Subsequently, the obtained powder mixture was subjected to provisional firing at 850 ℃ to obtain a provisionally fired powder. The obtained calcined powder was subjected to wet pulverization by a ball mill to obtain Li₃V₂(PO₄)₃And (3) powder.

With respect to the above Li₃V₂(PO₄)₃100 parts of the powder was mixed with 15 parts of a binder and 65 parts of dihydroterpineol as a solvent, and the mixture was dispersed to prepare a positive electrode active material layer paste and a negative electrode active material layer paste.

(preparation of paste for Positive electrode collector layer and paste for negative electrode collector layer)

As materials for the positive electrode collector layer and the negative electrode collector layer, 10 parts of a binder and 50 parts of dihydroterpineol as a solvent were added to 100 parts of Cu powder and mixed and dispersed to prepare a paste for the positive electrode collector layer and a paste for the negative electrode collector layer.

(preparation of conductive paste for external electrode)

20 parts of dihydroterpineol as a solvent was added to 100 parts of Cu powder, and mixed and dispersed to prepare a conductive material paste for external electrodes.

Using these pastes, a laminated all-solid secondary battery was produced as follows.

(preparation of Positive electrode Unit)

A solid electrolyte layer paste was applied to a PET film as a substrate by a doctor blade method and dried to form a solid electrolyte layer green sheet. Next, a paste for a positive electrode active material layer, a paste for a positive electrode collector layer, and a paste for a positive electrode active material layer are sequentially printed on the green sheet for a solid electrolyte layer by a screen printing method, thereby forming a green sheet for a positive electrode in which a positive electrode active material layer, a positive electrode collector layer, and a positive electrode active material layer are sequentially stacked. Next, a solid electrolyte layer having a height substantially flush with the positive electrode is formed on the edge other than the positive electrode by a screen printing method using a paste for a solid electrolyte layer, and dried. Then, the obtained laminate was peeled from the PET film to produce a positive electrode unit.

(preparation of negative electrode Unit)

A negative electrode cell was produced in the same manner as the production of the positive electrode cell described above, except that the paste for the negative electrode active material layer and the paste for the negative electrode current collector layer were used instead of the paste for the positive electrode current collector layer and the paste for the positive electrode active material layer.

< Process for producing cell laminate >

The positive electrode unit and the negative electrode unit are alternately stacked in plurality. Next, a plurality of solid electrolyte layer green sheets were stacked on both principal surfaces of the obtained laminate to obtain a unit laminate. The obtained cell laminate was thermocompression bonded using a press.

The solid electrolyte layer green sheet was produced by applying a solid electrolyte layer paste onto a PET film by a doctor blade method and drying the paste.

< groove Forming Process >

Next, as shown in fig. 17, from the upper surface side of the obtained unit laminated body 120, a first groove 161 and a second groove 162 are formed using a fine laser processing machine.

< conductive Material filling Process >

Next, as shown in fig. 18, the first groove 161 and the second groove 162 are filled with a conductive material paste for external electrodes by a screen printing method, and then dried. Thus, the first and second grooves 161 and 162 are filled with a conductive material. Further, in the case where the grooves were not sufficiently filled with the conductive material paste for external electrodes by 1-time screen printing, screen printing was performed a plurality of times.

< Process for Forming auxiliary electrode >

Next, as shown in fig. 19, the conductive material paste for external electrodes described above is printed on the surface of the upper surface of the cell laminate 120 by a screen printing method and dried to form the sub-electrode 164.

< cutting step >

Next, as shown in fig. 20, in the first groove 161 and the second groove 162 filled with the conductive material 163, a slit 165 penetrating the unit laminate 120 was formed using a fine laser processing machine, and a unit laminate sheet (unfired lamination type all-solid secondary battery) was obtained.

< firing Process >

Then, the obtained unit laminate sheet was heated to 750 ℃ at a heating rate of 200 ℃/hr under a nitrogen atmosphere, fired at that temperature for 2 hours, and then allowed to cool to room temperature. The dimensions of the laminated all-solid secondary battery 11 obtained after firing were 5.50mm × 4.00mm × 1.02m m.

[ example 7]

A laminated all-solid secondary battery 12 according to a seventh embodiment was fabricated in the same manner as in example 6, except that a groove was formed by using a fine laser processing machine around the first groove 161 and the second groove 162 filled with the conductive material 163 of the cell laminate 120 before the sub-electrode forming step, and the sub-electrode was formed in this groove in the sub-electrode forming step. Further, the dimensions of the laminated all-solid secondary battery 12 obtained after firing were 5.50mm × 4.00mm × 1.00 mm. In the laminated all-solid secondary battery 12 obtained in example 7, the sub-electrode was formed in the groove, and therefore, the height was reduced by 0.02mm as compared with the laminated all-solid secondary battery 11 obtained in example 6.

[ example 8]

A laminated all-solid secondary battery 13 according to an eighth embodiment was produced in the same manner as in example 6, except that the sub-electrode was not formed. Further, the dimensions of the laminated all-solid secondary battery 13 obtained after firing were 5.50mm × 4.00mm × 1.00 mm. The laminated all-solid secondary battery 13 obtained in example 8 had no sub-electrode formed, and therefore had a height reduced by 0.02mm compared to the laminated all-solid secondary battery 11 obtained in example 6.

[ example 9]

In the cell laminate producing step, the solid electrolyte layer is not formed on the upper surface 225 after the cell laminate 220 is produced as shown in fig. 24, and the sub-electrode forming step is not performed after the conductive material filling step, but the solid electrolyte layer 250c is formed on the surface of the upper surface of the cell laminate 220 as shown in fig. 27 (solid electrolyte layer forming step), except that the same operation as in example 6 is performed, and the laminated all-solid secondary battery 14 of the ninth embodiment is produced. Further, the dimensions of the laminated all-solid secondary battery 14 obtained after firing were 5.50mm × 4.00mm × 1.00 mm.

Comparative example 2

The cell laminate obtained in the cell laminate production step of example 6 was cut, and the obtained cell laminate pieces were fired to obtain the multilayer sintered body 20 shown in fig. 29 and 30. The dimensions of the laminated sintered body 20 were 5.50mm × 4.00mm × 1.00 mm.

The first side surface 21 of the laminated sintered body 20 was immersed in the conductive material paste for external electrode used in example 6 to a depth facing the negative electrode 40, and the conductive material paste for external electrode was applied to the first side surface 21. Next, the second side surface 22 of the stacked sintered body 20 is immersed in the conductive material paste for external electrodes to a depth facing the positive electrode 30, and the conductive material paste for external electrodes is applied to the second side surface 22. The applied external electrode conductive material paste was dried to produce a conventional laminated all-solid-state secondary battery 10 shown in fig. 29 and 30. Further, the dimensions of the obtained laminated all-solid secondary battery 10 were 5.54mm × 4.04mm × 1.04 mm. In the laminated all-solid secondary battery 10 obtained in comparative example 1, the external electrode is formed on the outer surface of the laminated sintered body 20, and therefore, the volume is increased by the thickness of the external electrode as compared with the laminated all-solid secondary batteries 11 to 14 obtained in examples 6 to 9.

[ evaluation ]

The charge/discharge capacity, the volumetric energy density, and the cycle characteristics of the laminated all-solid secondary batteries manufactured in examples 6 to 9 and comparative example 2 were measured by the following methods. The results are shown in table 2 below together with the cross-sectional shapes of the positive and negative external electrodes.

< Charge-discharge capacity >

The measurement of the initial charge-discharge capacity was performed in an environment of 25 ℃. The charging capacity was a capacity measured when the battery voltage became 1.6V and was held at a constant current of 0.1C for 3 hours. The discharge capacity is a capacity measured after charging and discharging at a constant current of 0.2C until the battery voltage becomes 0V. The discharge capacity is a relative value when the discharge capacity of the laminated all-solid secondary battery produced in comparative example 2 is taken as 100.

< volumetric energy density >

The volumetric energy density is calculated using the following calculation formula.

Volume energy density (mWh/L) ═ initial discharge capacity (μ Ah) × average discharge voltage (V) ÷ volume of stacked all-solid secondary battery (mm)³)

Table 2 shows the relative values of the discharge capacities of the laminated all-solid secondary battery produced in comparative example 2 as 100.

< Charge-discharge cycle characteristics >

The measurement of the charge/discharge capacity described above was regarded as 1 cycle, and the charge/discharge capacity retention rate after repeating the cycle for 1000 cycles was evaluated as the charge/discharge cycle characteristic. The charge-discharge cycle characteristics in the present embodiment are calculated by the following calculation formula.

Charge-discharge capacity maintenance rate after 1000 cycles [% ] (discharge capacity after 1000 cycles (μ Ah) ÷ initial discharge capacity (μ Ah)) × 100

[ Table 2]

The laminated all-solid secondary batteries of examples 6 to 9 in which the upper end portions of the positive electrode external electrode 61 and the negative electrode external electrode 71 were located inward (lower side) of the upper end portion in the lamination direction of the laminated sintered body 20 were improved in charge/discharge capacity, volumetric energy density, and cycle characteristics as compared with the laminated all-solid secondary battery of comparative example 1.

In particular, the stacked all-solid secondary battery of example 7 in which the lower surface sub-electrode 62a and the lower surface sub-electrode 72a were embedded in the lower surface 26 of the stacked sintered body 20 had an improved volumetric energy density. This is presumably because the lower surface sub-electrode 62a and the lower surface sub-electrode 72a are embedded in the lower surface 26 of the laminated sintered body 20, and the volume of the laminated all-solid secondary battery is smaller than that of example 6.

Industrial applicability

The present invention can provide a laminated all-solid-state secondary battery capable of improving charge/discharge capacity, pulse discharge cycle characteristics, and cycle characteristics.

Description of the reference numerals

310. 311, 312, 313, 314, 315 … laminated all-solid-state secondary battery, 320 … laminate, 321 … first side, 322 … second side, 323 … third side, 324 … fourth side, 325 … upper surface, 326 … lower surface, 330 … positive electrode, 331 … positive electrode current collector layer, 332 … positive electrode active material layer, 340 … negative electrode, 341 … negative electrode current collector layer, 342 … negative electrode active material layer, 350 … solid electrolyte layer, 360, 361, 362, 363, 364, 365 … positive electrode external electrode, 360a … side sub-electrode, 360b, 361b, 363b … upper surface sub-electrode, 360c, 361c, 362c, 363c 364c, … lower surface sub-electrode, 370, 371, 372, 373, 374, 375 … negative electrode external electrode, 370a … side sub-electrode, 370b, 371b, 373b, … upper surface sub-electrode, 373c, 371c, 372c, 373c, … c, 10. 11, 12, 13, 14 … laminated all-solid-state secondary battery, 20 … laminated sintered body, 21 … first side face, 21a … concave portion, 22 … second side face, 22a … concave portion, 23 … third side face, 24 … fourth side face, 25 … upper face, 26 … lower face, 30 … positive electrode, 31 … positive electrode collector layer, 32 … positive electrode active material layer, 40 … negative electrode, 41 … negative electrode collector layer, 42 … negative electrode active material layer, 50 … solid electrolyte layer, 60, 61, 62, 63, 64 … positive electrode external electrode, 60a, 61a, 62a … lower face sub-electrode, 60b … upper face sub-electrode, 60c … side face sub-electrode, 70, 71, 72, 73, 74 … negative electrode external electrode, 70a, 71a, 72a … lower face sub-electrode, 70b … upper face sub-electrode, 70c … side face sub-electrode, 120 … unit 121 …, 122 second side, 123 third side, 124 fourth side, 125 upper surface, 126 lower surface, 130 positive electrode, 131 positive electrode current collector layer, 132 positive electrode active material layer, 133 spacing section, 135 positive electrode unit, 140 negative electrode, 141 negative electrode current collector layer, 142 negative electrode active material layer, 143 spacing section, 145 negative electrode unit, 150a, 150b, 150c solid electrolyte layer, 161 first groove, 162 second groove, 163 conductive material, 164 secondary electrode, 220 unit laminate, 225 upper surface, 226 lower surface, 230 positive electrode, 231 positive electrode current collector layer, 232 positive electrode active material layer, 233 spacing section, 235 positive electrode unit, 240 negative electrode, 241 negative electrode current collector layer, 242 negative electrode active material layer, 243 spacing section, 245 negative electrode unit, 250a, 250b, 250c solid electrolyte layer, 261 … first groove, 262 … second groove, 263 … conductive material.