阅读说明：本技术 锂离子二次电池 (Lithium ion secondary battery ) 是由 谷内拓哉 大田正弘 有贺稔之 于 2021-03-19 设计创作，主要内容包括：本发明所要解决的问题在于,提供一种锂离子二次电池,其在将锂离子二次电池的集电体极耳捆束来与引线端子接合时,能够防止电极端部的破裂。为了解决上述问题,本发明的锂离子二次电池具备：锂离子二次电池本体,其在反复配置有具备正极集电体的正极、固体电解质及具备负极集电体的负极的层叠体中,集电体从层叠体的端面各自向同一方向引出,而构成多个集电体极耳；及,引线端子,其与多个集电体极耳电连接；并且,集电体极耳与引线端子是经由导电性极耳引导零件来连接。(The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a lithium ion secondary battery capable of preventing breakage of an electrode end portion when current collector tabs of the lithium ion secondary battery are bundled and joined to a lead terminal. In order to solve the above problems, a lithium ion secondary battery according to the present invention includes: a lithium ion secondary battery body in which a laminate of a positive electrode having a positive electrode current collector, a solid electrolyte, and a negative electrode having a negative electrode current collector is repeatedly arranged, the current collectors being drawn out from respective end faces of the laminate in the same direction to form a plurality of current collector tabs; and lead terminals electrically connected to the plurality of collector tabs; the current collector tab and the lead terminal are connected to each other through a conductive tab guide member.)

1. A lithium ion secondary battery is provided with:

a lithium ion secondary battery body in which a laminate of a positive electrode having a positive electrode current collector, an electrolyte, and a negative electrode having a negative electrode current collector is repeatedly arranged, wherein at least one of the current collectors of the two electrodes is drawn out in the same direction from each of end faces of the laminate to form a plurality of current collector tabs; and a process for the preparation of a coating,

lead terminals electrically connected to the plurality of collector tabs;

at least one of the current collector tabs and the lead terminals are connected by conductive tab guiding members;

the conductive tab guiding member includes a covering portion covering the current collector tab, and an extending portion extending from the covering portion and connected to one end side of the lead terminal.

2. The lithium ion secondary battery according to claim 1, wherein the extension portion has flexibility.

3. The lithium ion secondary battery according to claim 1 or 2, wherein the plurality of extension portions are connected to one end side of the lead terminal in a bundled state.

4. The lithium ion secondary battery according to claim 1 or 2, wherein a plurality of the covering portions are joined to each other.

5. The lithium-ion secondary battery according to claim 1 or 2, wherein the lithium-ion secondary battery body is a solid battery.

6. The lithium ion secondary battery according to claim 1 or 2, wherein the current collector is a conductive porous body, and the current collector tab is a conductive sheet obtained by pressing the conductive porous body.

Technical Field

The present invention relates to a lithium ion secondary battery.

Background

Conventionally, lithium ion secondary batteries have been widely used as secondary batteries having high energy density. A lithium ion secondary battery has a structure in which a solid electrolyte (separator) is present between a positive electrode and a negative electrode and a liquid electrolyte (electrolytic solution) is filled.

The electrolyte of a lithium ion secondary battery is generally a flammable organic solvent, and therefore safety particularly against heat may be a problem. Therefore, a solid-state battery using an inorganic solid electrolyte instead of an organic liquid electrolyte has also been proposed (see patent document 1). The solid-state battery based on the solid electrolyte can eliminate the problem of heat as compared with a battery using an electrolytic solution, and can meet the demand for higher capacity and/or higher voltage by lamination, and further can contribute to compactness.

In a lithium ion secondary battery using either a liquid electrolyte or a solid electrolyte, a positive electrode including a positive electrode current collector, a solid electrolyte, and a negative electrode including a negative electrode current collector are also repeatedly stacked, and integration with an exterior body is performed in the following manner: in each of the positive electrode and the negative electrode, a plurality of current collector tabs are drawn out from the same direction, and the plurality of current collector tabs are bundled and then connected to lead terminals.

Fig. 3 is a diagram showing a state of bonding between a conventional lithium ion secondary battery main body and lead terminals. As shown in fig. 3(a), a plurality of current collector tabs 12a, 12b, 12c, 12d drawn out from the lithium ion secondary battery body 100 are bundled and then joined together with the lead terminal 200 by welding at a joining portion 500. In this case, since the distances between the current collector tab and the lead terminals are different depending on the lead terminals and are 12a, 12d > 12b, 12c, if the lengths are the same, the more the outer side is subjected to a stronger tension, which causes the electrode end portion from which the current collector tab is drawn to be broken. In particular, as shown in fig. 3(b), this is remarkable when the position of the lead terminal 200 is shifted downward from the center. At this time, the uppermost current collector tab 12a is subjected to the strongest tension, and thus the electrode end portions are likely to be broken. In addition, in the solid-state battery, since the electrode itself is a solid, the breakage of the electrode end portion becomes more likely to occur.

Further, it has been proposed to use a thin conductive porous body of a metal or the like having a mesh structure as a current collector constituting a positive electrode and a negative electrode in a solid-state battery. By filling the inside of the mesh structure with an electrode material, the amount of active material per unit area of the electrode layer is increased, contributing to an increase in the capacity of the battery. Examples of the current collector having such a mesh structure include a metal foam. The metal foam has an advantage as a current collector in that the pore diameter is uniform and the surface area is large (see patent documents 2 and 3). When the conductive porous body is used as the current collector, the current collector tab drawn therefrom is a conductive sheet obtained by pressing the drawn conductive porous body, and the conductive sheet has higher rigidity and is less likely to bend than the metal foil. Therefore, if tension or stress is applied as shown in fig. 3, not only the electrode end portions but also the current collector tab itself is likely to be broken or torn.

[ Prior Art document ]

(patent document)

Patent document 1: japanese patent laid-open No. 2000-106154

Patent document 2: japanese laid-open patent publication No. 7-099058

Patent document 3: japanese laid-open patent publication No. 8-329954

Disclosure of Invention

[ problems to be solved by the invention ]

The present invention has been made in view of the above-mentioned background art, and an object thereof is to prevent breakage of an electrode end portion when current collector tabs of a lithium ion secondary battery are bundled and joined to lead terminals.

[ means for solving problems ]

The present inventors have intensively studied a method for connecting a current collector tab and a lead terminal in a lithium ion secondary battery in order to solve the above-mentioned problems, and as a result, have found that the above-mentioned problems can be solved by a tab guide member having conductivity interposed between the current collector tab and the lead terminal, and have completed the present invention. Specifically, the present invention provides the following techniques.

(1) A lithium ion secondary battery is provided with:

a lithium ion secondary battery body in which a laminate of a positive electrode having a positive electrode current collector, an electrolyte, and a negative electrode having a negative electrode current collector is repeatedly arranged, wherein at least one of the current collectors of the two electrodes is drawn out in the same direction from each of end faces of the laminate to form a plurality of current collector tabs; and a process for the preparation of a coating,

lead terminals electrically connected to the plurality of collector tabs;

at least one of the current collector tabs and the lead terminals are connected by conductive tab guiding members;

the conductive tab guiding member includes a covering portion covering the current collector tab, and an extending portion extending from the covering portion and connected to one end side of the lead terminal.

(2) The lithium-ion secondary battery according to (1), wherein the extension portion has flexibility.

(3) The lithium-ion secondary battery according to (1) or (2), wherein the plurality of extending portions are connected to one end side of the lead terminal in a bundled state.

(4) The lithium-ion secondary battery according to any one of (1) to (3), wherein a plurality of the covering portions are joined to each other.

(5) The lithium-ion secondary battery according to any one of (1) to (4), wherein the lithium-ion secondary battery body is a solid-state battery.

(6) The lithium-ion secondary battery according to any one of (1) to (5), wherein the current collector is a conductive porous body, and the current collector tab is a conductive sheet obtained by pressing the conductive porous body.

(Effect of the invention)

According to the present invention, when the current collector tabs of the lithium ion secondary battery are bundled and joined to the lead terminals, the electrode end portions can be prevented from being broken.

Drawings

Fig. 1 is a schematic side sectional view showing a state of bonding between a lithium ion secondary battery body and a lead terminal according to embodiment 1 of the present invention.

Fig. 2 is an enlarged view of the vicinity of the collector tab in fig. 1.

Fig. 3 shows a state where a conventional lithium ion secondary battery body and lead terminals are joined; fig. 3(a) is a schematic side sectional view of a lead terminal in a central portion thereof, and fig. 3(b) is a schematic side sectional view of the lead terminal in a state where the lead terminal is displaced downward.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below is an example of the present invention, and the present invention is not limited to the following description. The following embodiments are described by taking a lithium ion solid state battery as an example, but the present invention is not limited to this example, and a lithium ion battery in which the electrolyte is a liquid is also included.

< integral constitution of lithium ion Secondary Battery >

First, the overall structure of the lithium-ion secondary battery of the present invention will be described with reference to fig. 1 and 2. Fig. 1 is a schematic side sectional view showing a joined state of a lithium ion secondary battery body 100 and a lead terminal 200 according to an embodiment of the present invention, and fig. 2 is an enlarged view of the vicinity of a collector tab in fig. 1. As shown in fig. 1, the lithium ion secondary battery is composed of a lithium ion secondary battery body 100, lead terminals 200, and conductive tab guides 300, and the lithium ion secondary battery body 100 and the lead terminals 200 are connected via the conductive tab guides 300.

As shown in fig. 2, the lithium ion secondary battery body 100 is a laminate having a structure in which a negative electrode 10, a positive electrode 20, and a solid electrolyte layer 30 disposed between the electrodes are repeatedly laminated. In this embodiment, the lamination unit of the negative electrode 10, the solid electrolyte layer 30, and the positive electrode 20 is further laminated repeatedly 4 times.

Each negative electrode 10 has a negative electrode active material layer 11 laminated on both surfaces of a negative electrode current collector 12, and each positive electrode 20 has a positive electrode active material layer 21 laminated on both surfaces of a positive electrode current collector 22. These layers may be different layers, or the negative electrode current collector and the negative electrode active material layer may be integrated as in the following example using a conductive porous material.

[ negative electrode active material layer ]

The negative electrode active material constituting the negative electrode active material layer 11 is not particularly limited, and a known material can be used as the negative electrode active material of the solid-state battery. The composition is also not particularly limited, and a solid electrolyte, a conductive aid, a binder, and the like may be contained. Examples of the negative electrode active material include: lithium metal; lithium alloys such as lithium-aluminum (Li-Al) alloys and lithium-indium (Li-In) alloys; li₄Ti₅O₁₂And the like lithium titanate; carbon materials such as carbon fiber and graphite.

[ negative electrode Current collector ]

The negative electrode current collector 12 is not particularly limited, and a known current collector that can be used for a negative electrode of a solid-state battery can be used. Examples thereof include: metal foils such as stainless steel (SUS) foil and copper (Cu) foil.

[ Positive electrode active Material layer ]

The positive electrode active material constituting the positive electrode active material layer 21 is not particularly limited, and a known material can be used as the positive electrode active material of the solid-state battery. The composition is also not particularly limited, and a solid electrolyte, a conductive aid, a binder, and the like may be contained. Examples of the positive electrode active material include: transition metal chalcogenides of titanium disulfide, molybdenum disulfide, niobium selenide, and the like; lithium nickelate (LiNiO)₂) Lithium manganate (LiMnO)₂、LiMn₂O₄) Lithium cobaltate (LiCoO)₂) And the like.

[ Positive electrode Current collector ]

The positive electrode current collector 22 is not particularly limited, and a known current collector that can be used for a positive electrode of a solid-state battery can be used. Examples thereof include: metal foils such as stainless steel (SUS) foil and aluminum (Al) foil.

[ electrode Tab of Current collector ]

The plurality of negative electrode current collector tabs 12a, 12b, 12c, and 12d are drawn out in a planar shape from one end surface of the laminate body in substantially parallel to one another in the same direction. In this embodiment, the negative electrode current collector tabs extend from the respective negative electrode current collectors 12.

The plurality of positive electrode collector tabs 22a, 22b, 22c, and 22d are also drawn out in a planar shape from the other end surface of the laminate body in substantially parallel to one another in the same direction. In this embodiment, the positive electrode current collectors 22 extend to form positive electrode current collector tabs.

In the present invention, as a result, the collector tab may be drawn out from each collector, and is not necessarily limited to extension, and the collector tab may be different members.

The width of the collector tab is set to be the maximum width of the composite material and is appropriately set so as to reduce the resistance of the collector tab according to the purpose of use, but is preferably 1mm to 1000mm, and more preferably 2mm to 300 mm. The thickness is generally about 5 to 50 μm, and the lead-out length is generally about 5 to 50 mm.

[ conductive sheet obtained using conductive porous Material ]

In the present invention, a conductive porous body can be used as the current collector. An example of the conductive porous body is a metal porous body, preferably a metal foam porous body (metal foam). Examples of the metal include: nickel, aluminum, stainless steel, titanium, copper, silver, and the like. As the current collector constituting the positive electrode, aluminum foam is preferable, and as the current collector constituting the negative electrode, copper foam and stainless steel foam can be preferably used.

Since the metal foam has a three-dimensional mesh structure, the current collecting performance and the active material retaining performance can be improved as compared with other conventional current collectors. Accordingly, the composite layer can be made thicker without an increase in resistance than when a metal foil is used as the current collector, and as a result, the capacity per unit area of the electrode can be increased. Further, for example, the metal foam has a higher porosity than the metal fiber sintered body, and therefore, the amount of the active material to be filled can be increased, and as a result, the capacity of the electrode can be increased.

The electrode is formed by filling an electrode material into the voids of the conductive porous body as a current collector. The electrode composite material contains an electrode active material, a solid electrolyte, and preferably an organic polymer compound (binder). The other components are not particularly limited, and may be optionally contained as components that can be used for producing an electrode of a solid-state battery.

When the conductive porous body is used as the current collector, a current collector tab is drawn from the conductive porous body. In this case, the lead-out portion includes at least a conductive porous body, and may be filled with or without an electrode material. The lead portion is pressed to a predetermined thickness and width by a predetermined pressing method such as roll pressing to eliminate voids, thereby forming a conductive sheet constituting a collector tab. The conductive sheet has rigidity and no flexibility in the collector tab itself, as compared with the foil. Therefore, the collector tab itself has a characteristic of being easily broken.

[ lead terminals ]

The lead terminal 200 has one end side electrically connected to the extended portion 320 of the conductive tab guide 300 located adjacent to the lithium ion secondary battery body 100 by welding or the like, and the other end side is extended from an exterior body such as a body film not shown in the figures, thereby forming an electrode portion of the exterior body.

The lead terminal 200 is not particularly limited, and is preferably a thin plate-like member such as aluminum (Al) or copper (Cu) that has flexibility and extends in the extending direction. Generally, the lead terminal 200 has a thickness of about 0.05mm to 5mm, which is thicker than the current collector tab.

< connection structure of lithium ion secondary battery body and lead terminal >

As shown in fig. 1, the lithium ion secondary battery is composed of a lithium ion secondary battery body 100, lead terminals 200, and conductive tab guiding members 300, and the lithium ion secondary battery body 100 and the lead terminals 200 are connected via the conductive tab guiding members 300. Although the positive-side connection structure is omitted in fig. 1, the positive-side connection structure may be the same, and in the present invention, the following connection structure may be applied to either or both of the positive-side and negative-side connection structures.

As described above, the negative electrode current collector tabs 12a, 12b, 12c, and 12d in fig. 1 are drawn out in a planar shape from one end surface of the laminate body in the same direction and in a state of being substantially parallel to each other. The number of the negative electrode collector tabs can be appropriately set according to the number of repeated laminations of the lamination unit.

[ conductive tab guide component 300]

(covering section)

As shown in fig. 1 and 2, the conductive tab guide member 300 includes a cylindrical covering portion 310 and an extending portion 320 extending from a reduced diameter portion of the covering portion 310. In the present invention, the covering portion 310 and the extending portion 320 may not be an integral body, or may be different members.

The covering portion 310 may have a substantially flat cylindrical tube portion 315 as a whole that can cover the entire collector tab, and the tube portion 315 may have an opening portion on one end side thereof, and the opening portion may have a rib 311. The rib 311 of the covering portion 310 abuts against the end face of the stacked body constituting the lithium ion secondary battery body 100, and ensures bonding to the end face. Note that an insulator edge treatment such as a resin may be applied between the rib 311 and the end face.

The cylindrical portion 315 is preferably inserted from the front end of the current collector tab and then joined to the current collector tab by crimping or the like. This enables the cylindrical portion 315 to be electrically connected to the current collector tab with certainty. Further, the covering portion 310 can physically protect the current collector tab, and can alleviate the current collector tab from being broken or subjected to a strong tension due to movement in the vertical direction. Therefore, the covering portion 310 preferably has a predetermined rigidity.

Examples of the conductive material constituting the covering portion 310 include an aluminum foil, a copper foil, and a stainless steel foil having a thickness of 0.05mm to 0.5 mm.

Although not shown, the peripheries of the cylindrical portion 315 and the rib 311 may be sealed with insulator resin such as resin. The covering portion 310 may not be cylindrical and may not cover the entire current collector tab, and may be in the following form: an electrical body tab having a plate or U-shape and covering a portion thereof.

(extension part)

The other end side of the cylindrical portion 315 gradually reduces in diameter to close the opening, and the portion extending therefrom constitutes an extending portion 320. The extending portion 320 is formed in a band shape, a plate shape, or a foil shape similar to the collector tab, reaches one end side of the lead terminal 200, and is joined to one end side of the joining portion 200 by welding or the like.

The extension 320 is preferably flexible. This makes it possible to relax the stress applied to the electrode, bundle the plurality of current collector tabs, and easily join the current collector tabs at the joint 200.

Examples of the conductive material constituting the extension 320 include aluminum foil, copper foil, stainless steel foil, and the like having a thickness of 0.05mm to 0.5 mm.

(joining part)

In the present embodiment, the conductive tab guide member 300 is used for any of the 4 collector tabs 12a, 12b, 12c, 12d, and the covering portions 310 are linearly connected to each other by the connecting portion 330 so as to extend across the thickness direction of the lithium ion secondary battery body 100. Accordingly, the 4 covering parts 310 are integrated, and the covering parts 310 can be prevented from moving independently. The same material as the covering portion 310 or the extending portion 320 can be used for the coupling portion 330.

In the present invention, the conductive tab guide members 300 may not be used for all the current collector tabs, and the conductive tab guide members 300 may be used only for specific current collector tabs, such as tabs of electrodes that are particularly prone to breakage.

In the present invention, the conductive tab guide members 300 may not be used for all the current collector tabs, and the conductive tab guide members 300 may be used only for specific current collector tabs, such as tabs of electrodes that are particularly prone to breakage.

(Joint part)

Then, the plurality of extensions 320 can be bundled with a bundling means (not shown) conventionally known as a bundling plate or a bundling roller. The bundle means a bundle (or bundle) in a side view of fig. 1, and in this embodiment, the planar extension portions 320 are stacked and laminated.

The plurality of extended portions 320 after the bundling are extended to the lead terminal 200 side in a bundled state or a substantially bundled state. Further, a joint portion 400 is formed at a position overlapping one end side (lithium ion secondary battery main body 100 side) of the lead terminal 200. That is, in the 2 nd joining part 400, the bundled plurality of extending parts 320 and the lead terminals 200 are joined by welding.

The joining in the present invention means a broad sense of joining including fusion joining, that is, fusion joining, which is a joining method in which heat, pressure, or both are applied to joining portions of 2 or more members, and if necessary, an appropriate filler is added to make the joining portions into 1 member after the integration; including welding, pressure welding, brazing (brazing).

As described above, according to the present invention, by connecting the current collector tab of the lithium ion secondary battery main body and the lead terminals via the conductive tab guide member, it is possible to reduce stress applied to the current collector tab and prevent breakage of the electrode. Further, by using the conductive tab guide member, the length of the current collecting tab can be made constant and shortened, and the current collecting tab can be connected to lead terminals disposed in various ways, thereby improving the degree of freedom of connection.

The present invention is effective for a lithium ion solid-state battery in which an electrode is solid and is easily broken. In particular, when the collector tab is a conductive sheet obtained by pressing a conductive porous body, the collector tab itself has rigidity and no flexibility. Therefore, the current collector tab itself is easily broken, and therefore the present invention is particularly preferably used.

Reference numerals

10: negative electrode

11: negative electrode active material layer

12: negative electrode current collector

12a, 12b, 12c, 12 d: negative electrode collector tab

20: positive electrode

21: positive electrode active material layer

22: positive electrode current collector

22a, 22b, 22c, 22 d: positive electrode collector tab

30: solid electrolyte layer

100: lithium ion secondary battery body

300: conductive tab guiding part

310: covering part

311: ribs

315: barrel part

320: extension part

330: connecting part

400: joint part