阅读说明：本技术 固体电池用线条正极、固体电池以及它们的制造方法 (Line positive electrode for solid-state battery, and methods for producing them ) 是由 銭朴 徳根敏生 川合光干 于 2019-05-23 设计创作，主要内容包括：不降低能量密度,而实现即使只进行3分钟左右的快速充电也可充电至100％的固体电池。本发明提供一种用于此的固体电池用线条正极、具有所述固体电池用线条正极的固体电池、所述固体电池用线条正极的制造方法、以及具有所述固体电池用线条正极的固体电池的制造方法。将构成固体电池的正极的结构设为丝状结构,制成在具有导电性的正极线条体的表面具备含有正极活性物质的正极活性物质层,进而在其外侧具有含有电解质的正极电解质层的固体电池用线条正极,并制成对所述固体电池用线条正极与具有丝状结构的固体电池用线条负极进行层叠而成的固体电池。(A solid-state battery which can be charged to 100% even when a rapid charge of about 3 minutes is performed without lowering the energy density is realized. The invention provides a string positive electrode for a solid-state battery used for the same, a solid-state battery with the string positive electrode for the solid-state battery, a manufacturing method of the string positive electrode for the solid-state battery, and a manufacturing method of the solid-state battery with the string positive electrode for the solid-state battery. The structure of a positive electrode constituting a solid-state battery is a filament structure, and a solid-state battery string positive electrode is produced, which is provided with a positive electrode active material layer containing a positive electrode active material on the surface of a conductive positive electrode string body, and further provided with a positive electrode electrolyte layer containing an electrolyte on the outer side thereof, and in which the solid-state battery string positive electrode and a solid-state battery string negative electrode having a filament structure are laminated.)

1. A wire positive electrode for a solid battery, characterized in that,

a positive electrode active material layer containing a positive electrode active material is provided on the surface of the conductive positive electrode filament,

the positive electrode active material layer has a positive electrode electrolyte layer containing an electrolyte on the outside thereof.

2. A solid-state battery comprising the string positive electrode for a solid-state battery according to claim 1 and a negative electrode, wherein the string positive electrode for a solid-state battery is characterized in that,

the negative electrode is a linear negative electrode for a solid-state battery comprising a negative electrode linear body having conductivity,

the line positive electrode for the solid battery and the line negative electrode for the solid battery are alternately laminated.

3. The solid-state battery according to claim 2, wherein the string negative electrode for a solid-state battery has a negative electrode active material layer containing a negative electrode active material on a surface of a negative electrode string body having conductivity.

4. The solid-state battery according to claim 2 or 3, wherein the solid-state battery string negative electrode has a negative electrode electrolyte layer containing an electrolyte on the outer side of the negative electrode string body.

5. The solid-state battery according to any one of claims 2 to 4, wherein a distance between the positive electrode umbilical member and the negative electrode umbilical member is 3.4 μm or less.

6. The solid-state battery according to claim 4 or 5, wherein a thickness of the positive electrode electrolyte layer is larger than a thickness of the negative electrode electrolyte layer.

7. A method for manufacturing a wire positive electrode for a solid-state battery, comprising:

a positive electrode active material layer forming step of forming a positive electrode active material layer containing a positive electrode active material on the surface of the conductive positive electrode filament; and

and a positive electrode electrolyte layer forming step of forming a positive electrode electrolyte layer containing an electrolyte on the outer side of the positive electrode active material layer.

8. A method for manufacturing a solid-state battery, comprising:

a lamination step of alternately laminating the string positive electrode for a solid-state battery according to claim 1 and a string negative electrode for a solid-state battery including a negative electrode string body having conductivity to obtain a positive-negative electrode laminate; and

and a compression step of compressing the positive-negative electrode laminate to bring the solid-state battery string positive electrode into close contact with the solid-state battery string negative electrode.

9. The method for manufacturing a solid-state battery according to claim 8, wherein the string negative electrode for a solid-state battery has a negative electrode active material layer containing a negative electrode active material on a surface of a negative electrode string body having conductivity,

in the stacking step, the positive electrode electrolyte layer is brought into contact with the negative electrode active material layer.

10. The method for manufacturing a solid-state battery according to claim 8, wherein the string negative electrode for a solid-state battery has a negative electrode electrolyte layer containing an electrolyte on the outside of the negative electrode active material layer,

in the stacking step, the positive electrode electrolyte layer and the negative electrode electrolyte layer are brought into contact with each other.

11. The method for manufacturing a solid-state battery according to any one of claims 8 to 10, wherein in the laminating step, the distance between the positive electrode umbilical member and the negative electrode umbilical member is 3.4 μm or less.

Technical Field

The present invention relates to a string positive electrode for a solid-state battery, a method for manufacturing the string positive electrode for the solid-state battery, and a method for manufacturing the solid-state 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 separator is interposed between a positive electrode and a negative electrode and a liquid electrolyte (electrolytic solution) is filled therein.

The electrolyte solution of a lithium ion secondary battery is generally a flammable organic solvent, and in particular, safety 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 secondary battery has a solid or gel-like electrolyte layer as an electrolyte layer between a positive electrode and a negative electrode. A solid-state battery using a solid electrolyte can solve the problem of heat, increase the voltage by lamination, and meet the demand for compactness, as compared with a battery using an electrolytic solution.

Although such a lithium ion secondary battery is repeatedly used by charge and discharge, it is necessary to further shorten the charging time of the lithium ion secondary battery. Currently, the charging time of an electric vehicle requires about 8 hours in normal charging and about 30 minutes in rapid charging.

In recent years, with an increase in energy consumption of equipment used, further high energy density of lithium ion secondary batteries has been desired. In addition, an electric storage device using a fiber-shaped positive electrode and a fiber-shaped negative electrode has been proposed for the purpose of increasing the capacity per unit volume of a lithium ion secondary battery (see patent document 2).

In patent document 2, a fiber positive electrode in which a specific positive electrode active material coating is formed on the surface of a fiber having conductivity is combined with a fiber negative electrode including a fiber having conductivity, thereby obtaining a power storage device having dramatically improved battery performance.

Here, in the solid-state battery, the factor that most affects the battery performance is the contact interface of the positive electrode active material and the positive electrode electrolyte layer. On the other hand, in the negative electrode, a contact interface between the negative electrode active material and the electrolyte is easily formed, and therefore, this is not problematic. As for the contact interface in the positive electrode, for example, a method of forming a contact interface in advance by coating a solid electrolyte on the surface of the positive electrode active material to suppress degradation of battery performance is also known.

However, in the power storage device using a fiber electrode described in patent document 2, the active material is coated with a solid electrolyte to form a negative electrode, and there is no description about a positive electrode.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent application laid-open No. 2000-106154

[ patent document 2] International publication No. 2011/007548 Manual

Disclosure of Invention

[ problems to be solved by the invention ]

The present inventors have studied aiming to charge a lithium ion secondary battery to 100% with the same degree of time as gasoline supply time. In addition, as one of methods for shortening the charging time of a lithium ion secondary battery, attention is paid to shortening the lithium ion conduction time.

The lithium ion conduction time of a lithium ion secondary battery is related to the lithium ion conduction resistance and the diffusion resistance caused by the diffusion of the lithium ion concentration. Further, it was found that: of the lithium ion conduction resistance and the lithium ion diffusion resistance, the latter resistance is large, and it is more effective to reduce the lithium ion diffusion resistance in order to realize rapid charging.

Here, in order to reduce the lithium ion diffusion resistance, the distance over which lithium ions move, that is, the distance between the positive electrode and the negative electrode may be shortened. According to the calculation of the invention, the following results are found: for example, in order to realize 100% charging in 3 minutes, which is the same as the gasoline supply time, in the case of a solid battery in which the electrolyte is solid or gel, the distance over which lithium ions move needs to be 3.4 μm or less.

As a method for making the distance for lithium ion movement to be 3.4 μm or less, for example, in the case of a solid-state battery, a method for reducing the thickness of the electrode mixture layer is most effective. However, since this method forms a thin film electrode, the energy density of the obtained solid battery will be sacrificed.

The present invention has been made in view of the above problems, and an object thereof is to realize a solid-state battery that can be charged to 100% even with a rapid charge of only about 3 minutes without reducing the energy density, and to provide a string positive electrode for a solid-state battery used for the solid-state battery, a solid-state battery having the string positive electrode for a solid-state battery, a method for producing the string positive electrode for a solid-state battery, and a method for producing the solid-state battery having the string positive electrode for a solid-state battery.

[ means for solving problems ]

The present inventors have conducted active studies on shortening the distance over which lithium ions move, i.e., the distance between the positive electrode and the negative electrode, without reducing the energy density. Then, it was found that: the above problems can be solved by forming the structure of the positive electrode constituting the solid-state battery into a filament-like structure, forming a solid-state battery string positive electrode having a positive electrode active material layer containing a positive electrode active material on the surface of a conductive positive electrode string body and further having a positive electrode electrolyte layer containing an electrolyte on the outer side thereof, and laminating the solid-state battery string positive electrode and a solid-state battery string negative electrode having a filament-like structure to form a solid-state battery.

That is, the present invention is a linear positive electrode for a solid-state battery, which has a positive electrode active material layer containing a positive electrode active material on the surface of a positive electrode linear body having conductivity, and has a positive electrode electrolyte layer containing an electrolyte on the outer side of the positive electrode active material layer.

The present invention is also a solid-state battery comprising the solid-state battery string positive electrode and a negative electrode, wherein the negative electrode is a solid-state battery string negative electrode comprising a negative electrode string body having conductivity, and the solid-state battery string positive electrode and the solid-state battery string negative electrode are alternately stacked.

The string negative electrode for a solid-state battery may have a negative electrode active material layer containing a negative electrode active material on the surface of a negative electrode string body having conductivity.

The string negative electrode for a solid-state battery may have a negative electrode electrolyte layer containing an electrolyte on the outside of the negative electrode string body.

The distance between the positive electrode assembly and the negative electrode assembly may be 3.4 μm or less.

The thickness of the positive electrode electrolyte layer may be greater than the thickness of the negative electrode electrolyte layer.

Another aspect of the present invention is a method for manufacturing a wire positive electrode for a solid battery, including: a positive electrode active material layer forming step of forming a positive electrode active material layer containing a positive electrode active material on the surface of the conductive positive electrode filament; and a positive electrode electrolyte layer forming step of forming a positive electrode electrolyte layer containing an electrolyte on the outer side of the positive electrode active material layer.

Another aspect of the present invention is a method for manufacturing a solid-state battery, including: a lamination step of alternately laminating the solid-state battery string positive electrode and a solid-state battery string negative electrode including a negative electrode string body having conductivity to obtain a positive-negative electrode laminate; and a compression step of compressing the positive-negative electrode laminate to bring the solid-state battery string-shaped positive electrode and the solid-state battery string-shaped negative electrode into close contact with each other.

The string negative electrode for a solid-state battery may have a negative electrode active material layer containing a negative electrode active material on the surface of a negative electrode string body having conductivity, and the positive electrode electrolyte layer may be brought into contact with the negative electrode active material layer in the stacking step.

The string negative electrode for a solid battery may have a negative electrode electrolyte layer containing an electrolyte on the outer side of the negative electrode active material layer, and in the laminating step, the positive electrode electrolyte layer and the negative electrode electrolyte layer may be brought into contact with each other.

In the laminating step, the distance between the positive electrode filament and the negative electrode filament may be 3.4 μm or less.

[ Effect of the invention ]

According to the linear positive electrode for a solid-state battery of the present invention, a solid-state battery that can be charged to 100% even when a rapid charge is performed for about 3 minutes can be realized without reducing the energy density. Therefore, when the solid-state battery including the linear positive electrode for a solid-state battery of the present invention is mounted on an automobile, the solid-state battery can be charged to 100% in the same time as the gasoline cut time.

Drawings

Fig. 1 is a view showing one embodiment of a linear positive electrode for a solid-state battery according to the present invention.

Fig. 2 is a view showing an embodiment of a linear negative electrode for a solid-state battery that can be used in the present invention.

Fig. 3(a) to 3(c) are views showing various embodiments of the string-shaped positive electrode for a solid-state battery according to the present invention and the string-shaped negative electrode for a solid-state battery that can be used in the present invention.

Fig. 4 is a diagram showing an embodiment of the solid-state battery according to the present invention.

Fig. 5 is a view showing an embodiment of a positive-negative electrode laminate of the solid-state battery according to the present invention.

Fig. 6 is a diagram showing the distance between the positive electrode and the negative electrode of the solid-state battery string.

Fig. 7 is a view showing an embodiment of a positive-negative electrode laminate of the solid-state battery according to the present invention.

Description of the symbols

10. 30, 70: line positive electrode for solid battery

11. 31: positive electrode line body

12. 32: positive electrode active material layer

13. 33: positive electrode electrolyte layer

20. 40, 80: line negative electrode for solid battery

21. 41: negative electrode line body

22. 42: negative electrode active material layer

23. 43: negative electrode electrolyte layer

100: solid-state battery

101: positive and negative electrode laminate

102: positive electrode joint

103: negative electrode tab

L, L': distance between positive electrode line body and negative electrode line body

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

< line positive electrode for solid Battery >

The linear positive electrode for a solid-state battery of the present invention has a thread-like structure, and has a positive electrode active material layer containing a positive electrode active material on the surface of a positive electrode linear body having conductivity, and a positive electrode electrolyte layer containing an electrolyte on the outer side of the positive electrode active material layer.

Fig. 1 is a view showing one embodiment of a linear positive electrode for a solid-state battery according to the present invention. The string positive electrode 10 for a solid-state battery according to one embodiment of the present invention has a positive electrode active material layer 12 containing a positive electrode active material on the surface thereof, with a positive electrode string body 11 having conductivity as the center. Further, the outer side thereof has a positive electrode electrolyte layer 13 containing an electrolyte. The linear positive electrode 10 for a solid-state battery according to one embodiment has a substantially circular cross-sectional shape.

[ shape ]

The shape of the filament to be the positive electrode cord for a solid-state battery of the present invention is not particularly limited, and examples of the cross section thereof include a substantially circular shape, a substantially polygonal shape, and the like. Among these, the distance from the positive electrode assembly as the center to the positive electrode electrolyte layer as the outermost layer is substantially equal, and therefore, a circular shape or a polygonal shape is preferable. Among polygons, a triangle, a quadrangle (square), a hexagon, and the like, which can be packed most densely, are preferable because the energy density is increased.

Further, when the positive-negative electrode laminate is formed by alternately laminating the filament to be the string negative electrode for the solid-state battery, if the shape of the string positive electrode for the solid-state battery is substantially the same as the shape of the string negative electrode for the solid-state battery, a more compact laminate can be formed, and as a result, the distance in which lithium ions move can be made shorter.

Fig. 3(a) to 3(c) and 5 show various embodiments of the linear positive electrode for a solid-state battery according to the present invention. The string positive electrode 30 for a solid-state battery shown in fig. 3(a) has a positive electrode active material layer 32 containing a positive electrode active material on the surface thereof, and further has a positive electrode electrolyte layer 33 containing an electrolyte on the outer side thereof, with a positive electrode string body 31 having conductivity as the center. The solid-state battery positive electrode 30 has a substantially rectangular cross section. The solid-state battery string positive electrode 50 in fig. 3(b) has a substantially triangular cross section, and the solid-state battery string positive electrode 70 in fig. 3(c) has a substantially octagonal cross section. The solid-state battery string positive electrode 70 shown in fig. 5 has a substantially hexagonal shape in cross section.

[ diameter ]

The diameter of the filament to be the string positive electrode of the solid-state battery of the present invention is not particularly limited, but is preferably in the range of 0.05 μm to 50 μm for the purpose of shortening the distance over which lithium ions travel, that is, the distance between the positive electrode and the negative electrode. Further, when the solid-state battery using the string positive electrode for a solid-state battery of the present invention is mounted on an automobile and it is desired that the charging time until 100% charging is 3 minutes, which is about the same as the gasoline cut-off time, the distance over which lithium ions must travel is 3.4 μm or less, and therefore the diameter of the yarn to be the solid-state battery positive electrode is preferably in the range of 0.1 μm to 4.0 μm.

[ Positive electrode line body ]

The positive electrode filament constituting the solid-state battery positive electrode of the present invention is a conductive filament.

(shape)

The shape of the filament to be the positive electrode filament is not particularly limited, and the cross section may be substantially circular, substantially polygonal, or may have a cross section having a modified shape. Among these, a roughened surface or a surface coated with carbon is preferable because the contact resistance with the active material can be reduced.

(Material)

The material of the filament to be the positive electrode filament is a material that exhibits a higher potential than the charge/discharge potential of the compound constituting the negative electrode. For example, if a material that provides a sufficiently high standard electrode potential with respect to the standard electrode potential of the solid-state battery linear negative electrode is selected, the characteristics as a solid-state battery are high, and a desired battery voltage can be realized.

In the present invention, examples of the material of the filament to be the positive electrode filament include a metal wire such as a carbon fiber, an aluminum wire, or a steel wire, or a metal-coated polyolefin, cotton, or silk yarn.

(diameter)

The diameter of the filament to be the positive electrode filament is not particularly limited, but is preferably in the range of 0.01 μm to 15 μm for the purpose of shortening the distance over which lithium ions travel, that is, the distance between the positive electrode and the negative electrode. Further, when a solid-state battery using the string positive electrode for a solid-state battery of the present invention is mounted on an automobile and it is desired that the charging time until 100% charging is 3 minutes, which is about the same as the gasoline cut-in time, the distance over which lithium ions must travel is 3.4 μm or less, and therefore the diameter of the string to be a positive electrode string is preferably in the range of 0.01 μm to 0.5 μm.

[ Positive electrode active Material layer ]

The positive electrode active material layer is a layer disposed on the surface of the positive electrode filament body, and contains a positive electrode active material. The positive electrode active material preferably contains a positive electrode active material having a voltage of 4.2V (vs. Li/Li) in the range of the operating voltage of the lithium ion secondary battery⁺) The above upper working limit potential. This can stably realize a battery with high energy density.

(Material)

The positive electrode active material layer usually contains a lithium compound as a positive electrode active material. The lithium compound is not particularly limited as long as it can be used as a positive electrode active material of a lithium ion secondary battery. For example, a lithium alloy or a lithium complex may be used.

The positive electrode active material layer may contain components other than the positive electrode active material, such as a conductive auxiliary agent, a binder, and a solid electrolyte. Examples of the conductive material include carbon materials such as acetylene black. Examples of the binder include: halogenated vinyl resins such as Polyvinylidene difluoride (PVDF).

(thickness)

The thickness of the positive electrode active material layer is not particularly limited as long as it can cover the positive electrode filament, but is preferably in the range of 0.03 to 49.9 μm for the purpose of shortening the distance over which lithium ions move, i.e., the distance between the positive electrode and the negative electrode. Further, when a solid-state battery using the string positive electrode for a solid-state battery of the present invention is mounted on an automobile and it is desired that the charging time until 100% charging is 3 minutes, which is about the same as the gasoline cut-in time, the distance over which lithium ions must travel is 3.4 μm or less, and therefore the thickness of the positive electrode active material layer is preferably in the range of 0.05 μm to 3.4 μm.

[ Positive electrode electrolyte layer ]

The positive electrode electrolyte layer is disposed outside the positive electrode active material layer and contains an electrolyte of the lithium ion solid state battery. In the present invention, there is no particular limitation as long as ion conduction can be performed between the string positive electrode for a solid-state battery and the string negative electrode for a solid-state battery, and the string positive electrode for a solid-state battery may be solid or gel.

(Material)

The electrolyte used in the string positive electrode for a solid-state battery is not particularly limited as long as it can be used for a lithium ion battery. For example, oxide-based or sulfide-based solid electrolytes are cited.

The positive electrode electrolyte layer may contain other components such as a binder, if necessary. The composition ratio of each substance contained in the positive electrode electrolyte layer is not particularly limited as long as the battery operates properly.

(thickness)

The thickness of the positive electrode electrolyte layer is not particularly limited, but is preferably in the range of 0.02 μm to 15 μm in order to shorten the distance over which lithium ions travel, that is, the distance between the positive electrode and the negative electrode, and to prevent short-circuiting between the positive electrode and the negative electrode when the string-shaped positive electrode for solid-state battery and the string-shaped negative electrode for solid-state battery are alternately stacked to form a positive-negative electrode stack. Further, when a solid-state battery using the string positive electrode for a solid-state battery of the present invention is mounted on an automobile and it is desired that the charging time until 100% charging is 3 minutes, which is about the same as the gasoline cut-in time, the distance over which lithium ions must travel is 3.4 μm or less, and therefore the thickness of the positive electrode electrolyte layer is preferably in the range of 0.03 μm to 0.1 μm.

The thickness of the positive electrode electrolyte layer is preferably larger than the thickness of the negative electrode electrolyte layer provided in the string negative electrode for a solid-state battery. In the solid-state battery, the factor that most affects the battery performance is the formation of a contact interface between the positive electrode active material and the positive electrode electrolyte layer in the positive electrode. On the other hand, in the anode, a contact interface of the anode active material with the electrolyte can be formed more easily. Therefore, the thickness of the positive electrode electrolyte layer on the positive electrode side becomes an important factor in the solid-state battery, and in the present invention, the thickness of the positive electrode electrolyte layer is preferably larger than the thickness of the negative electrode electrolyte layer.

[ other layers ]

The string positive electrode for a solid-state battery of the present invention includes a positive electrode string body having conductivity, a positive electrode active material layer containing a positive electrode active material, and a positive electrode electrolyte layer containing an electrolyte, which are essential layers, and may have any layers other than these layers.

Examples of the optional layer include a coating layer. The coating layer is preferably provided between the positive electrode active material layer and the positive electrode electrolyte layer, whereby the adhesion between the positive electrode active material layer and the positive electrode electrolyte layer can be improved and the peeling can be prevented.

Method for manufacturing wire positive electrode for solid battery

The wire-shaped positive electrode for a solid-state battery of the present invention can be obtained by a manufacturing method including the steps of: a positive electrode active material layer forming step of forming a positive electrode active material layer containing a positive electrode active material on the surface of the conductive positive electrode filament; and a positive electrode electrolyte layer forming step of forming a positive electrode electrolyte layer containing an electrolyte on the outer side of the positive electrode active material layer.

[ Positive electrode active material layer Forming Process ]

In the positive electrode active material layer forming step, a positive electrode active material layer containing a positive electrode active material is formed on the surface of the conductive positive electrode filament. The method for forming the positive electrode active material layer is not particularly limited, and examples thereof include: a method of preparing a positive electrode mixture slurry, immersing a positive electrode filament in the slurry, and then drying, a thin film forming method such as sputtering, Chemical Vapor Deposition (CVD), pulse laser film forming method, electric field Deposition method, plating method, or the like.

[ Positive electrode electrolyte layer Forming Process ]

In the positive electrode electrolyte layer forming step, a positive electrode electrolyte layer containing an electrolyte is formed on the outer side of the positive electrode active material layer. The method for forming the positive electrode electrolyte layer is not particularly limited, and examples thereof include: a method of preparing a slurry or a solution containing a solid electrolyte precursor, immersing filaments intended to form a positive electrode electrolyte layer in the slurry or the solution, and then drying and firing, a thin film forming method such as sputtering, CVD, or a pulsed laser film forming method, an electric field deposition method, an electroplating method, or the like.

[ embodiment 1: film-making method

Embodiment 1 of the method for manufacturing a string positive electrode for a solid-state battery of the present invention is a method for manufacturing a string positive electrode for a solid-state battery by a thin film formation method. Since the layer formation by the thin film formation method can form a thin layer, it is a preferable method for shortening the distance between the positive electrode and the negative electrode and shortening the moving distance of lithium ions.

(Positive electrode active material layer Forming step)

The positive electrode active material layer forming step of embodiment 1 is a step of forming a thin-film positive electrode active material layer by depositing a material to be a positive electrode active material layer on the surface of a conductive positive electrode filament by a thin-film deposition method such as sputtering, CVD, or a pulse laser film-forming method, and then drying the deposited material.

(Positive electrode electrolyte layer Forming step)

After the formation of the positive electrode active material layer, if necessary, another layer such as a coating layer is formed, and then a substance to be a positive electrode electrolyte layer is deposited on the outside of the positive electrode active material layer by a thin film deposition method such as sputtering, CVD, or a pulse laser film deposition method, followed by drying to form a thin film positive electrode electrolyte layer.

[ embodiment 2: coating/calcining method ]

Embodiment 2 of the method for manufacturing a string positive electrode for a solid-state battery of the present invention is a method for manufacturing a string positive electrode for a solid-state battery by a coating/firing method. This method is advantageous in terms of manufacturing costs as compared with the film-forming method.

(Positive electrode active material layer Forming step)

In the positive electrode active material layer forming step of embodiment 2, a positive electrode mixture slurry is prepared, and a positive electrode filament is immersed in the slurry and then dried to form a positive electrode active material layer.

The positive electrode mixture slurry prepared in embodiment 2 may be the same as the slurry used in a known method of forming a positive electrode by coating. Specifically, a slurry is prepared which contains a positive electrode active material as nanoparticles, a binder such as PVDF, and, if necessary, a conductive auxiliary agent, and further a solvent. The mixing ratio and the production method are not particularly limited, and examples thereof include: a method of mixing by mechanical grinding such as ball mill.

(Positive electrode electrolyte layer Forming step)

After the formation of the positive electrode active material layer, another layer such as a coating layer is formed as necessary, a slurry containing a solid electrolyte precursor is prepared, a filament to be formed into the positive electrode electrolyte layer is impregnated into the slurry, and then, drying and firing are performed to form a thin film positive electrode electrolyte layer.

As the slurry containing the solid electrolyte precursor prepared in embodiment 2, for example, a slurry containing Li is cited₂S、P₂S₅An ethanol/Tetrahydrofuran (THF) mixed solution of LiBr, or LiCl. The subsequent calcination temperature is, for example, 550 ℃.

< solid Battery >

The solid-state battery of the present invention is a solid-state battery including the string positive electrode and the negative electrode for a solid-state battery of the present invention. The negative electrode constituting the solid-state battery of the present invention is a linear negative electrode for a solid-state battery including a negative electrode linear body having conductivity, and constitutes a positive-negative electrode laminate in which the linear positive electrode for a solid-state battery of the present invention and the linear negative electrode for a solid-state battery are alternately laminated.

Fig. 4 shows an embodiment of the solid-state battery according to the present invention. In fig. 4, a solid-state battery 100 includes a positive-negative electrode laminate 101 in which positive electrode strands for a solid-state battery and negative electrode strands for a solid-state battery are alternately laminated, and includes a positive electrode tab 102 and a negative electrode tab 103.

[ line positive electrode for solid-state battery ]

The string positive electrode for a solid-state battery constituting the solid-state battery of the present invention is the string positive electrode for a solid-state battery of the present invention.

[ line negative electrode for solid-state battery ]

The solid-state battery negative electrode constituting the solid-state battery of the present invention has a filament-like structure and includes a negative electrode filament having conductivity. The string negative electrode for a solid-state battery constituting the solid-state battery of the present invention optionally has a negative electrode active material layer containing a negative electrode active material on the surface of the negative electrode string body, and optionally has a negative electrode electrolyte layer containing an electrolyte.

Fig. 2 is a view showing an embodiment of the linear negative electrode for a solid-state battery according to the present invention. The string-type negative electrode 20 for a solid battery according to one embodiment has a negative electrode active material layer 22 containing a negative electrode active material on the surface thereof, with a negative electrode string body 21 having conductivity as the center. Further, the negative electrode has a negative electrode electrolyte layer 23 containing an electrolyte on the outside thereof. The string-shaped negative electrode 20 for a solid-state battery according to one embodiment has a substantially circular cross-sectional shape.

[ shape ]

The shape of the filament of the string negative electrode for a solid-state battery constituting the solid-state battery of the present invention is not particularly limited, and examples of the cross section thereof include a substantially circular shape, a substantially polygonal shape, and the like. Among polygons, a triangle, a quadrangle (square), a hexagon, and the like, which can be packed most densely, are preferable because the energy density is increased.

Further, when the positive-negative electrode laminate is formed by alternately laminating the solid-state battery string positive electrodes of the present invention, if the shape of the solid-state battery string negative electrode is substantially the same as the shape of the solid-state battery string positive electrode, a more compact laminate can be formed, and as a result, the distance in which lithium ions move can be made shorter.

Fig. 3(a) to 3(c) and 5 show various embodiments of the solid-state battery linear negative electrode constituting the solid-state battery of the present invention. The string-type negative electrode 40 for a solid-state battery shown in fig. 3(a) has a negative electrode active material layer 42 containing a negative electrode active material on the surface thereof and a negative electrode electrolyte layer 43 containing an electrolyte on the outer side thereof, with a negative electrode string body 41 having conductivity as the center. The solid-state battery linear negative electrode 40 has a substantially quadrangular cross section. The solid-state battery linear negative electrode 60 in fig. 3(b) has a substantially triangular cross section, and the solid-state battery linear negative electrode 80 in fig. 3(c) has a substantially octagonal cross section. The solid-state battery linear negative electrode 80 shown in fig. 5 has a substantially hexagonal cross section.

[ diameter ]

The diameter of the filament of the string negative electrode for a solid-state battery constituting the solid-state battery of the present invention is not particularly limited, but is preferably in the range of 0.05 μm to 50 μm for the purpose of shortening the distance over which lithium ions move, i.e., the distance between the positive electrode and the negative electrode. Further, when the solid-state battery of the present invention is mounted on an automobile and the charging time until 100% charging is 3 minutes, which is about the same as the gasoline cut-off time, the distance over which lithium ions must travel is 3.4 μm or less, and therefore the diameter of the filament to be used as the string negative electrode for the solid-state battery is preferably in the range of 0.1 μm to 4.0 μm.

(negative electrode line body)

The negative electrode filament constituting the negative electrode for a solid-state battery used in the solid-state battery of the present invention is a conductive filament. When the material of the filament to be the negative electrode filament is a negative electrode active material for a lithium ion electrode, the filament may be used as it is as a negative electrode. When the material of the filament itself is not a negative electrode active material for a lithium ion electrode, a negative electrode active material layer containing a negative electrode active material is preferably disposed on the surface of the negative electrode filament.

(shape)

The shape of the negative electrode filament is not particularly limited, and the cross section may be substantially circular, substantially polygonal, or may have a cross section having a modified shape. Of these, a circular shape or a polygonal shape is preferable. In addition, among polygons, a triangle, a quadrangle (square), a hexagon, or the like, which can be packed most densely, is preferable because the energy density is increased.

(Material)

The material of the negative electrode filament is not particularly limited, and examples thereof include a metal wire such as a carbon fiber, a copper wire, and a nickel wire, and a polyolefin, cotton, and yarn coated with a metal.

(diameter)

The diameter of the filament to be the negative electrode filament is not particularly limited, but is preferably in the range of 0.01 μm to 15 μm for the purpose of shortening the distance over which lithium ions travel, that is, the distance between the positive electrode and the negative electrode. Further, when a solid-state battery using the string positive electrode for a solid-state battery of the present invention is mounted on an automobile and it is desired that the charging time until 100% charging is 3 minutes, which is about the same as the gasoline cut-in time, the distance over which lithium ions must travel is 3.4 μm or less, and therefore the diameter of the filament to be a negative electrode string is preferably in the range of 0.01 μm to 0.5 μm.

[ negative electrode active material layer ]

The negative electrode active material layer is a layer arbitrarily disposed on the surface of the negative electrode filament, and contains a negative electrode active material. For example, in the case of using carbon fibers as the negative electrode assembly, the carbon fibers themselves may become the negative electrode active material, and therefore it is not necessary to form a negative electrode active material layer on the surface of the negative electrode assembly. However, even in this case, the anode active material layer may be formed arbitrarily.

(Material)

The negative electrode active material contained in the negative electrode active material layer is not particularly limited as long as it can be used as a negative electrode active material in a lithium ion secondary battery. Examples of the graphite-based carbon include natural graphite, artificial graphite, and amorphous coated graphite.

The negative electrode active material layer may contain components other than the negative electrode active material, such as a thickener, a binder, and a solid electrolyte. Examples of the thickener include celluloses such as Carboxymethyl cellulose (CMC). Examples of the binder include rubbers such as Styrene-butadiene rubber (SBR) and halogenated vinyl resins such as polyvinylidene fluoride (PVDF).

(thickness)

The thickness of the negative electrode active material layer disposed arbitrarily is not particularly limited as long as it covers the negative electrode filament, but is preferably in the range of 0.03 to 49.9 μm for the purpose of shortening the distance over which lithium ions move, i.e., the distance between the positive electrode and the negative electrode. Further, when the solid-state battery of the present invention is mounted on an automobile and the charging time until 100% charging is 3 minutes, which is about the same as the gasoline cut-in time, the distance over which lithium ions must travel is 3.4 μm or less, and therefore the thickness of the negative electrode active material layer is preferably in the range of 0.05 μm to 3.4 μm.

[ negative electrode electrolyte layer ]

The negative electrode electrolyte layer is a layer that is arbitrarily disposed outside the negative electrode assembly, and contains an electrolyte of a lithium ion solid state battery. In the present invention, there is no particular limitation as long as ion conduction can be performed between the solid-state battery string positive electrode and the solid-state battery string negative electrode, and the solid state may be a gel state.

(Material)

The electrolyte used for the string negative electrode for a solid-state battery is not particularly limited as long as it can be used for a lithium ion battery. For example, oxide-based or sulfide-based solid electrolytes are cited.

The negative electrode electrolyte layer may contain other components such as a binder, if necessary. The composition ratio of each substance contained in the negative electrode electrolyte layer is not particularly limited as long as the battery operates properly.

(thickness)

The thickness of the negative electrode electrolyte layer is not particularly limited, but is preferably in the range of 0.02 μm to 15 μm in order to shorten the distance over which lithium ions travel, that is, the distance between the positive electrode and the negative electrode, and to prevent short-circuiting between the positive electrode and the negative electrode when the string-shaped positive electrode for solid battery and the string-shaped negative electrode for solid battery are alternately stacked to form a positive-negative electrode stack. Further, when the solid-state battery of the present invention is mounted on an automobile and the charging time until 100% charging is 3 minutes, which is about the same as the gasoline cut time, the distance over which lithium ions must travel is 3.4 μm or less, and therefore the thickness of the negative electrode electrolyte layer is preferably in the range of 0.03 μm to 0.1 μm.

[ laminate of Positive and negative electrodes ]

The solid-state battery of the present invention has a positive-negative electrode laminate in which the linear positive electrode for a solid-state battery of the present invention and the linear negative electrode for a solid-state battery are alternately laminated.

(laminated Structure)

The lamination structure of the positive and negative electrode laminate is not particularly limited, and examples thereof include: the yarn of the string positive electrode for a solid-state battery and the yarn of the string negative electrode for a solid-state battery are alternately overlapped in the same direction, or the yarn of the string positive electrode for a solid-state battery and the yarn of the string negative electrode for a solid-state battery are woven in a plain weave, twill weave or the like.

Fig. 5 and 7 show an embodiment of a positive-negative electrode laminate of a solid-state battery according to the present invention. The positive-negative electrode laminate body shown in fig. 5 and 7 is an a-a sectional view of the positive-negative electrode laminate body 101 of the solid-state battery according to the embodiment of the present invention shown in fig. 4.

In the positive-negative electrode laminate shown in fig. 5, the string positive electrode 70 for a solid-state battery having a hexagonal cross section and the string negative electrode 80 for a solid-state battery having a hexagonal cross section are arranged closely and alternately so as to form a honeycomb shape in cross section through the solid electrolytes of the respective filament yarns. In the positive-negative electrode laminate shown in fig. 7, string-shaped positive electrodes 10 having a substantially circular cross section and string-shaped negative electrodes 20 having a substantially circular cross section are alternately arranged substantially in parallel via solid electrolytes of the respective filament yarns.

(distance between positive electrode filament and negative electrode filament)

In the positive-negative electrode laminate, the distance between the positive electrode filament existing at the center of the solid-state battery string positive electrode and the negative electrode filament existing at the center of the solid-state battery string negative electrode is the distance over which lithium ions move. Therefore, in the present invention, it is preferable to shorten this distance, and the distance between the positive electrode umbilical member and the negative electrode umbilical member is preferably in the range of 0.1 μm to 100 μm. Further, when the solid-state battery of the present invention is mounted on an automobile and the charging time until 100% charging is 3 minutes, which is about the same as the gasoline cut time, it is preferable that the distance over which lithium ions move, that is, the distance between the positive electrode umbilical member and the negative electrode umbilical member is 3.4 μm or less.

Fig. 6 and 7 show the distance between the positive electrode filament and the negative electrode filament. In fig. 6, the distance between the positive electrode filament existing at the center of the solid-state battery string positive electrode 70 and the negative electrode filament existing at the center of the solid-state battery string negative electrode 80 is L. In fig. 7, the distance between the positive electrode umbilical member present at the center of the solid-state battery string positive electrode 10 and the negative electrode umbilical member present at the center of the solid-state battery string negative electrode 20 is L'.

< method for manufacturing solid Battery

The method for manufacturing a solid-state battery of the present invention includes: a lamination step of alternately laminating the line positive electrode for a solid battery of the present invention and the line negative electrode for a solid battery to obtain a positive-negative electrode laminate; and a compression step of compressing the positive-negative electrode laminate to bring the string-shaped positive electrode for a solid-state battery into close contact with the string-shaped negative electrode for a solid-state battery.

[ laminating Process ]

In the lamination step, the linear positive electrode for a solid-state battery of the present invention and the linear negative electrode for a solid-state battery are alternately laminated to obtain a positive-negative electrode laminate. The method of alternately laminating is not particularly limited, and examples thereof include: a method of alternately forming layers by arranging the yarn of the string positive electrode for a solid state battery and the yarn of the string negative electrode for a solid state battery so as to be oriented in the same direction, a method of weaving the yarn of the string positive electrode for a solid state battery and the yarn of the string negative electrode for a solid state battery into a plain weave, a twill weave, or the like, and the like.

[ compression Process ]

In the compression step, the positive-negative electrode laminate obtained in the lamination step is compressed to bring the string-shaped positive electrode for a solid-state battery and the string-shaped negative electrode for a solid-state battery into close contact with each other. The method of compression is not particularly limited, and examples thereof include: uniaxial pressing, rolling, and the like.

In the case of a solid-state battery string negative electrode having a negative electrode active material layer on the surface of a negative electrode string body, the positive electrode electrolyte layer and the negative electrode active material layer are laminated in contact with each other in the lamination step, and the positive electrode active material layer and the negative electrode active material layer are pressure-bonded without a gap through the positive electrode electrolyte layer in the compression step.

In the case of a solid-state battery string negative electrode having a negative electrode electrolyte layer as the outermost layer, the positive electrode electrolyte layer and the negative electrode electrolyte layer are laminated in contact with each other in the lamination step, and the positive electrode electrolyte layer and the negative electrode electrolyte layer are integrally pressure-bonded in the compression step.