JP7639663B2 - Manufacturing method for all-solid-state batteries - Google Patents

Description

This disclosure relates to a method for manufacturing an all-solid-state battery.

All-solid-state batteries have attracted attention because they use a solid electrolyte between the positive and negative electrodes instead of an electrolyte solution containing an organic solvent.

Patent Document 1 discloses an all-solid-state battery having an adhesive means for adhering a current collector to a battery unit stacked adjacent to the current collector.

JP 2017-204377 A

There is a demand for improving the energy density of all-solid-state batteries. In an electrode laminate in which a negative electrode, a solid electrolyte layer, and a positive electrode are laminated, if the electrode laminate is cut into a single piece and the sides are made flush, and then the sides are fixed with an insulating layer such as tape, the insulating layer may protrude onto the surface of the positive electrode, and the excess insulating layer on the surface of the positive electrode may apply a local load to the electrode laminate.
Also, the extra insulating layer on the surface of the positive electrode increases the size of the solid-state battery, reducing the energy density of the solid-state battery.

This disclosure has been made in consideration of the above-mentioned circumstances, and has as its main objective the provision of a method for manufacturing an all-solid-state battery that can improve the energy density of the all-solid-state battery.

The method for producing an all-solid-state battery according to the present disclosure is a method for producing an all-solid-state battery having a first electrode layer, a solid electrolyte layer, a second electrode layer, and a second current collector, in this order, on both sides of a first current collector, the method comprising:
obtaining a laminate in which the first electrode layer, the solid electrolyte layer, and the second electrode layer are laminated in this order on both sides of the first current collector;
A step of cutting at least one side surface of the laminate in the lamination direction to make the surface flush;
disposing an insulating layer on a surface of the second current collector in an area adjacent to an area where the laminate is to be disposed, thereby forming a bonded body of the second current collector and the insulating layer;
The method is characterized by comprising a step of: placing the laminate in a region on the surface of the second current collector where the laminate is to be placed, so that the second electrode layer is in contact with the second current collector, and adhering the insulating layer to a side surface of the laminate that is flush with the surface of the laminate.

The present disclosure can provide a method for manufacturing an all-solid-state battery that can improve the energy density of the all-solid-state battery.

FIG. 1 is a flowchart showing an example of a method for producing an all-solid-state battery according to the present disclosure. FIG. 2 is a diagram showing an example of a laminate before a cutting process. FIG. 3 is a diagram showing an example of a laminate after the cutting process. FIG. 4 is a diagram showing an outline of the (3) bonded body forming step and (4) bonding step of Example 1. FIG. 5 is a diagram showing an outline of the (3) bonded body forming step and (4) bonding step of Example 2. FIG. 6 is a diagram showing an outline of the (3) bonded body forming step and (4) bonding step of Example 3. FIG. 7 is a diagram showing an outline of the (3) bonded body forming step and (4) bonding step of Comparative Example 1. FIG. 8 is a diagram showing an outline of the (3) bonded body forming step and (4) bonding step of Comparative Example 2.

The method for producing an all-solid-state battery according to the present disclosure is a method for producing an all-solid-state battery having a first electrode layer, a solid electrolyte layer, a second electrode layer, and a second current collector, in this order, on both sides of a first current collector, the method comprising:
obtaining a laminate in which the first electrode layer, the solid electrolyte layer, and the second electrode layer are laminated in this order on both sides of the first current collector;
A step of cutting at least one side surface of the laminate in the lamination direction to make the surface flush;
disposing an insulating layer on a surface of the second current collector in an area adjacent to an area where the laminate is to be disposed, thereby forming a bonded body of the second current collector and the insulating layer;
The method is characterized by comprising a step of: placing the laminate in a region on the surface of the second current collector where the laminate is to be placed so that the second electrode layer is in contact with the second current collector; and adhering the insulating layer to a side surface of the laminate that is flush with the surface of the laminate.

1 is a flowchart showing an example of a method for producing an all-solid-state battery according to the present disclosure, in which 11 denotes a first current collector, 12 denotes a first electrode layer, 13 denotes a solid electrolyte layer, 14 denotes a second electrode layer, 15 denotes a second current collector, and 16 denotes an insulating layer.
As shown in FIG. 1 , the method for producing an all-solid-state battery according to the present disclosure includes (1) a laminate obtaining step, (2) a cutting step, (3) a bond forming step, and (4) a bonding step.
The (3) bonded body forming step may be performed before the (4) bonding step, and may be performed before, simultaneously with, or after the (1) laminate obtaining step, and may be performed before, simultaneously with, or after the (2) cutting step.

(1) Stacked Body Obtaining Step The stacked body obtaining step is a step of obtaining a stacked body in which the first electrode layer, the solid electrolyte layer, and the second electrode layer are stacked in this order on both sides of the first current collector.
The first electrode layer can be a positive electrode layer or a negative electrode layer. When the first electrode layer is a positive electrode layer, the second electrode layer, which is its counter electrode layer, is a negative electrode layer, and when the first electrode layer is a negative electrode layer, the second electrode layer is a positive electrode layer.
The method for laminating the first electrode layer, the solid electrolyte layer, and the second electrode layer in this order on both sides of the first current collector is not particularly limited, and any conventionally known method can be appropriately adopted.

(2) Cutting Step The cutting step is a step of cutting at least one side surface in the stacking direction of the laminate to make it flush.
The cutting method is not particularly limited, and examples thereof include laser irradiation.
The side surfaces to be flush with each other need only be at least one side surface, and may be only one side surface.

(3) Assembly Formation Step The assembly formation step is a step of arranging an insulating layer in an area adjacent to the area on the surface of the second current collector where the laminate is to be arranged, and forming an assembly of the second current collector and the insulating layer.
The joining method is not particularly limited, and when the insulating layer has adhesive properties, the second current collector and the insulating layer may be bonded to each other.
In the all-solid-state battery, the second current collector has a region that does not face the laminate and a region that faces the laminate, i.e., the dimension of the second current collector in the planar direction is larger than the dimension of the laminate in the planar direction.
The position at which the insulating layer is placed is not particularly limited as long as it is an area adjacent to the area on the surface of the second collector where the laminate is intended to be placed, and it may be a position where it can be adhered to the flush side of the laminate in the bonding process described below.
The thickness of the insulating layer (height in the stacking direction) may be the same as or different from the thickness of the laminate (height in the stacking direction), and may be within the range of the thickness of the laminate ± the thickness of the second electrode layer. When the thickness of the insulating layer is greater than the thickness of the laminate, the thickness of the insulating layer may be adjusted to be approximately the same as the thickness of the laminate by pressing, heating, etc. This allows the height of the laminate and the insulating layer to be matched.

The material of the insulating layer may be any material having insulating properties, may be a material having adhesive properties, or may be an adhesive. The adhesive used for the insulating layer is not particularly limited as long as it is solid and has adhesive properties. Examples of the adhesive include tacky resins and hot melt agents. Examples of tacky resins include acrylic resins, rubber resins, silicone resins, and urethane resins. There is no particular limitation on the hot melt agent as long as it is a resin with a melting point of 140°C or less, and examples of the hot melt agent include ethylene-vinyl acetate resins and polyethylene naphthalate resins.

(4) Bonding process The bonding process is a process of placing the laminate in the area on the surface of the second current collector where the laminate is to be placed so that the second electrode layer is in contact with the second current collector, and bonding the insulating layer to a side surface of the laminate that is flush with the surface of the laminate.
The insulating layer can be used as a positioning member when placing the laminate on the surface of the second current collector.
The bonding method is not particularly limited, and the insulating layer and the laminate may be bonded via an adhesive, or if the insulating layer itself has adhesive properties, the laminate and the insulating layer may be bonded directly to each other.

[Electrode layer]
The electrode layer contains an electrode active material, and optionally contains a solid electrolyte, a conductive material, a binder, and the like.
The electrode layer is a positive electrode layer or a negative electrode layer. Two electrode layers having different types of electrode active materials may be prepared, and one may be used as a positive electrode layer and the other as a negative electrode layer.
As the electrode active material, any material that can be used as an active material for an all-solid-state battery can be used, and materials similar to those exemplified as the positive electrode active material and the negative electrode active material described later can be used.
As the solid electrolyte, the same ones as those exemplified in the solid electrolyte layer described later can be exemplified.
Examples of the conductive material and binder include the same materials as those exemplified for the positive electrode layer described below.
The thickness of the electrode layer is not particularly limited, but may be, for example, 10 to 100 μm, or 10 to 20 μm.

[Current collector]
As the current collector, the same ones as those exemplified as the positive electrode current collector and the negative electrode current collector described later can be used.

[All-solid-state battery]
The all-solid-state battery of the present disclosure may include a positive electrode including a positive electrode layer and a positive electrode current collector, a solid electrolyte layer, and a negative electrode including a negative electrode layer and a negative electrode current collector.
The all-solid-state battery has a first electrode layer, a solid electrolyte layer, a second electrode layer, and a second current collector, in this order, on both sides of a first current collector.
One of the first electrode layer and the second electrode layer is a positive electrode layer and the other is a negative electrode layer. The first current collector is a positive electrode current collector if the first electrode layer is a positive electrode layer, and is a negative electrode current collector if the first electrode layer is a negative electrode layer. The second current collector is a positive electrode current collector if the second electrode layer is a positive electrode layer, and is a negative electrode current collector if the second electrode layer is a negative electrode layer.
The all-solid-state battery may be a battery unit in which a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, a negative electrode current collector, a negative electrode layer, a solid electrolyte layer, a positive electrode layer, and a positive electrode current collector are stacked in this order.
The all-solid-state battery may be a battery unit in which a negative electrode current collector, a negative electrode layer, a solid electrolyte layer, a positive electrode layer, a positive electrode current collector, a positive electrode layer, a solid electrolyte layer, a negative electrode layer, and a negative electrode current collector are stacked in this order.
The solid-state battery may be a stack of two or more battery units.

[Positive electrode]
The positive electrode includes a positive electrode layer and a positive electrode current collector.

[Positive electrode layer]
The positive electrode layer contains a positive electrode active material, and may contain, as optional components, a solid electrolyte, a conductive material, a binder, and the like.

There is no particular limitation on the type of the positive electrode active material, and any material that can be used as an active material for an all-solid-state battery can be used. Examples of the positive electrode active material include metallic lithium (Li), lithium alloys, LiCoO ₂ , LiNi _0.8 Co _0.15 Al _0.05 O ₂ , LiNi _x Co _1-x O ₂ (0<x<1), LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiMnO ₂ , Li-Mn spinel substituted with a different element, lithium titanate, lithium metal phosphate, LiCoN, Li ₂ SiO ₃ , and Li ₄ SiO ₄ , transition metal oxides, TiS ₂ , Si, SiO ₂ , Si alloys, and lithium storage intermetallic compounds. Examples of the Li-Mn spinel _{substituted with} different elements _{include LiMn1.5Ni0.5O4, LiMn1.5Al0.5O4 , LiMn1.5Mg0.5O4 , LiMn1.5Co0.5O4 , LiMn1.5Fe0.5O4 , and LiMn1.5Zn0.5O4 .} Examples of _{the lithium} titanate include _Li4Ti5O12 . Examples of the _lithium metal phosphate _{include LiFePO4} , _LiMnPO4 , _LiCoPO4 , and _{LiNiPO4 . Examples} of _the transition _metal oxide include _V2O5 and _MoO3 . Examples of lithium-storing intermetallic compounds include Mg ₂ Sn, Mg ₂ Ge, Mg ₂ Sb, and Cu ₃ Sb.
Examples of lithium alloys include Li-Au, Li-Mg, Li-Sn, Li-Si, Li-Al, Li-B, Li-C, Li-Ca, Li-Ga, Li-Ge, Li-As, Li-Se, Li-Ru, Li-Rh, Li-Pd, Li-Ag, Li-Cd, Li-In, Li-Sb, Li-Ir, Li-Pt, Li-Hg, Li-Pb, Li-Bi, Li-Zn, Li-Tl, Li-Te, and Li-At. Examples of Si alloys include alloys with metals such as Li, and may also be alloys with at least one metal selected from the group consisting of Sn, Ge, and Al.
The shape of the positive electrode active material is not particularly limited, and may be particulate. When the positive electrode active material is particulate, the positive electrode active material may be primary particles or secondary particles.
A coating layer containing a Li ion conductive oxide may be formed on the surface of the positive electrode active material, because this can suppress the reaction between the positive electrode active material and the solid electrolyte.
Examples of Li ion conductive oxides include LiNbO ₃ , Li ₄ Ti ₅ O ₁₂ , and Li ₃ PO ₄ . The thickness of the coating layer is, for example, 0.1 nm or more, and may be 1 nm or more. On the other hand, the thickness of the coating layer is, for example, 100 nm or less, and may be 20 nm or less. The coating layer may cover, for example, 70% or more of the surface of the positive electrode active material, or may cover 90% or more.

As the solid electrolyte, the same ones as those exemplified in the solid electrolyte layer can be exemplified.
The content of the solid electrolyte in the positive electrode layer is not particularly limited, but may be, for example, within a range of 1 mass % to 80 mass % when the total mass of the positive electrode layer is taken as 100 mass %.

The conductive material may be a known material, such as a carbon material and metal particles. The carbon material may be at least one selected from the group consisting of acetylene black, furnace black, VGCF, carbon nanotubes, and carbon nanofibers. Among them, from the viewpoint of electronic conductivity, at least one selected from the group consisting of VGCF, carbon nanotubes, and carbon nanofibers may be used. The metal particles may be particles of Ni, Cu, Fe, SUS, etc.
The content of the conductive material in the positive electrode layer is not particularly limited.

Examples of the binder include acrylonitrile butadiene rubber (ABR), butadiene rubber (BR), polyvinylidene fluoride (PVdF), and styrene butadiene rubber (SBR). The content of the binder in the positive electrode layer is not particularly limited.

The thickness of the positive electrode layer is not particularly limited, but may be, for example, 10 to 100 μm, or 10 to 20 μm.

The positive electrode layer can be formed by a conventionally known method.
For example, a positive electrode active material and, if necessary, other components are put into a solvent and stirred to prepare a positive electrode layer slurry, and the positive electrode layer slurry is applied onto one side of a support and dried to obtain a positive electrode layer.
Examples of the solvent include butyl acetate, butyl butyrate, mesitylene, tetralin, heptane, and N-methyl-2-pyrrolidone (NMP).
The method for applying the positive electrode layer slurry onto one surface of the support is not particularly limited, and examples thereof include a doctor blade method, a metal mask printing method, an electrostatic application method, a dip coating method, a spray coating method, a roll coating method, a gravure coating method, and a screen printing method.
The support can be appropriately selected from those having self-supporting properties and is not particularly limited. For example, metal foils such as Cu and Al can be used.

As another method for forming the positive electrode layer, the positive electrode layer may be formed by pressure molding a powder of a positive electrode mixture containing a positive electrode active material and other components as necessary. When the powder of the positive electrode mixture is pressure molded, a press pressure of about 1 MPa to 2000 MPa is usually applied.
The method of applying pressure is not particularly limited, but examples thereof include a method of applying pressure using a plate press, a roll press, or the like.

[Positive electrode current collector]
The positive electrode current collector may be a known metal that can be used as a current collector for an all-solid-state battery. Examples of such metals include metal materials containing one or more elements selected from the group consisting of Cu, Ni, Al, V, Au, Pt, Mg, Fe, Ti, Co, Cr, Zn, Ge, and In. Examples of the positive electrode current collector include SUS, aluminum, nickel, iron, titanium, and carbon.
The shape of the positive electrode current collector is not particularly limited, and may be in various shapes such as a foil shape, a mesh shape, etc. The thickness of the positive electrode current collector varies depending on the shape, but may be, for example, in the range of 1 μm to 50 μm, or in the range of 5 μm to 20 μm.

[Negative electrode]
The negative electrode includes a negative electrode layer and a negative electrode current collector.

[Negative electrode layer]
The negative electrode layer contains at least a negative electrode active material, and optionally contains a solid electrolyte, a conductive material, a binder, and the like.
Examples of the negative electrode active material include graphite, mesocarbon microbeads (MCMB), highly oriented pyrolytic graphite (HOPG), hard carbon, soft carbon, lithium alone, lithium alloys, Si alone, Si alloys, and Li ₄ Ti ₅ O _12. As the lithium alloys and Si alloys, the same ones as those exemplified in the positive electrode active material can be used.
The shape of the negative electrode active material is not particularly limited, and examples thereof include a particulate shape, a plate shape, etc. When the negative electrode active material is particulate, the negative electrode active material may be primary particles or secondary particles.
The conductive material and binder used in the negative electrode layer may be the same as those exemplified in the positive electrode layer, and the solid electrolyte used in the negative electrode layer may be the same as those exemplified in the solid electrolyte layer.
The thickness of the negative electrode layer is not particularly limited, but may be, for example, 10 to 100 μm, or 10 to 20 μm.
The content of the negative electrode active material in the negative electrode layer is not particularly limited, but may be, for example, 20% by mass to 90% by mass.

[Negative electrode current collector]
The material of the negative electrode current collector may be a material that does not alloy with Li, and examples of the material include SUS, copper, and nickel. Examples of the shape of the negative electrode current collector include foil and plate. The planar shape of the negative electrode current collector is not particularly limited, and examples of the shape include a circle, an ellipse, a rectangle, and any polygonal shape. The thickness of the negative electrode current collector varies depending on the shape, and may be, for example, in the range of 1 μm to 50 μm, or in the range of 5 μm to 20 μm.

[Solid electrolyte layer]
The solid electrolyte layer includes at least a solid electrolyte.
As the solid electrolyte contained in the solid electrolyte layer, a known solid electrolyte that can be used in an all-solid-state battery can be appropriately used, and examples of such inorganic solid electrolytes include a sulfide-based solid electrolyte, an oxide-based solid electrolyte, a hydride-based solid electrolyte, a halide-based solid electrolyte, and a nitride-based solid electrolyte. The sulfide-based solid electrolyte may contain sulfur (S) as a main component of the anion element. The oxide-based solid electrolyte may contain oxygen (O) as a main component of the anion element. The hydride-based solid electrolyte may contain hydrogen (H) as a main component of the anion element. The halide-based solid electrolyte may contain a halogen (X) as a main component of the anion element. The nitride-based solid electrolyte may contain nitrogen (N) as a main component of the anion element.

The sulfide-based solid electrolyte may be a sulfide glass, a crystallized sulfide glass (glass ceramics), or a crystalline material obtained by subjecting a raw material composition to a solid-phase reaction treatment.
The crystalline state of the sulfide-based solid electrolyte can be confirmed, for example, by subjecting the sulfide-based solid electrolyte to powder X-ray diffraction measurement using CuKα radiation.

The sulfide glass can be obtained by subjecting a raw material composition (e.g., _a mixture of _Li2S and _P2S5 ) to an amorphous process. Examples of the amorphous process include mechanical milling.

Glass ceramics can be obtained, for example, by heat treating a sulfide glass.
The heat treatment temperature may be any temperature higher than the crystallization temperature (Tc) of the sulfide glass observed by thermal analysis, and is usually 195° C. or higher. On the other hand, there is no particular upper limit to the heat treatment temperature.
The crystallization temperature (Tc) of the sulfide glass can be measured by differential thermal analysis (DTA).
The heat treatment time is not particularly limited as long as it is a time that can obtain the desired crystallinity of the glass ceramics, but is, for example, in the range of 1 minute to 24 hours, and particularly, in the range of 1 minute to 10 hours.
The method of heat treatment is not particularly limited, but for example, a method using a baking furnace can be mentioned.

Examples of oxide-based solid electrolytes include solid electrolytes containing Li element, Y element (Y is at least one of Nb, B, Al, Si, P, Ti, Zr, Mo, W, and S), and O element. Specific examples of oxide- _based solid electrolytes include garnet _-type solid _electrolytes such as _Li7La3Zr2O12 , Li7 _{-xLa3 (} Zr2 _{- xNbx} ) _O12 (0≦x≦2), and _Li5La3Nb2O12 ; perovskite-type solid electrolytes such as (Li,La) _TiO3 , (Li,La) _NbO3 , and (Li,Sr)(Ta _, Zr) _{O3 ;} Nasicon-type solid electrolytes such as Li(Al,Ti)( _PO4 ) _{3 and} Li(Al,Ga)( _PO4 ) ₃ ; Li-P-O-based solid electrolytes such as _{Li3PO4 and} LIPON (a compound in which part of the O _{in Li3PO4} is replaced with N); and _{Li3BO 3} , and compounds in which part of O in Li ₃ BO ₃ is replaced with C.

The hydride-based solid electrolyte contains, for example, Li and a complex anion containing hydrogen, such as (BH ₄ ) ⁻ , (NH ₂ ) ⁻ , (AlH ₄ ) ⁻ , and (AlH ₆ ) ³⁻ .
An example of the halide solid electrolyte is Li _6-3z Y _z X ₆ (X is at least one of Cl and Br, and z satisfies 0<z<2).
An example of the nitride-based solid electrolyte is Li ₃ N.

The solid electrolyte may be in the form of particles from the viewpoint of ease of handling.
The average particle size of the solid electrolyte particles is not particularly limited, but may be, for example, 10 nm or more, and may be 100 nm or more, whereas the average particle size of the solid electrolyte particles is, for example, 25 μm or less, and may be 10 μm or less.

In this disclosure, unless otherwise specified, the average particle size of particles is the volume-based median diameter (D50) value measured by laser diffraction/scattering particle size distribution measurement. In addition, in this disclosure, the median diameter (D50) is the diameter (volume average diameter) at which the cumulative volume of particles is half (50%) of the total volume when the particles are arranged in order from smallest to largest particle size.

The solid electrolyte may be used alone or in combination of two or more kinds. When two or more kinds of solid electrolytes are used, the two or more kinds of solid electrolytes may be mixed, or two or more layers of the solid electrolyte may be formed to form a multilayer structure.
The proportion of the solid electrolyte in the solid electrolyte layer is not particularly limited, but is, for example, 50% by mass or more, and may be in the range of 60% by mass or more and 100% by mass or less, 70% by mass or more and 100% by mass or less, or may be 100% by mass.

The solid electrolyte layer may contain a binder from the viewpoint of expressing plasticity. Examples of such binders include the materials exemplified as the binders used in the positive electrode layer. However, in order to facilitate high output, the binder may be contained in the solid electrolyte layer in an amount of 5 mass% or less from the viewpoint of preventing excessive aggregation of the solid electrolyte and enabling the formation of a solid electrolyte layer having a uniformly dispersed solid electrolyte.

The thickness of the solid electrolyte layer is not particularly limited, and is usually 0.1 μm or more and 1 mm or less.
The method for forming the solid electrolyte layer includes a method of applying a slurry for the solid electrolyte layer containing a solid electrolyte onto a support and drying it, and a method of pressurizing a powder of a solid electrolyte material containing a solid electrolyte. The support may be the same as those exemplified for the positive electrode layer. When pressurizing the powder of the solid electrolyte material, a press pressure of about 1 MPa to 2000 MPa is usually applied.
The method of applying pressure is not particularly limited, but may be any of the pressure applying methods exemplified in the formation of the positive electrode layer.

The all-solid-state battery may include an exterior body that houses the laminate, a restraining member, and the like, as necessary.
The material of the exterior body is not particularly limited as long as it is stable to the electrolyte, and examples of the material include polypropylene, polyethylene, and resins such as acrylic resin.
The restraining member may be any known member usable as a restraining member for an all-solid-state battery, as long as it can apply a restraining pressure in the stacking direction to the laminate. For example, a restraining member having a plate-shaped portion sandwiching both surfaces of the laminate, a rod-shaped portion connecting the two plate-shaped portions, and an adjustment portion connected to the rod-shaped portion and adjusting the restraining pressure by a screw structure or the like can be used. The adjustment portion can apply a desired restraining pressure to the laminate.
The restraining pressure is not particularly limited, but may be, for example, 0.1 MPa or more, 1 MPa or more, or 5 MPa or more. By increasing the restraining pressure, there is an advantage that the contact between the layers is easily improved. On the other hand, the restraining pressure may be, for example, 100 MPa or less, 50 MPa or less, or 20 MPa or less. If the restraining pressure is too high, the restraining member is required to have high rigidity, and the restraining member may become large.

The all-solid-state battery may be a primary battery or a secondary battery, and may be a secondary battery in particular. The secondary battery can be repeatedly charged and discharged. The secondary battery is useful, for example, as an in-vehicle battery. The all-solid-state battery may be an all-solid-state lithium secondary battery or an all-solid-state lithium ion secondary battery.
Examples of the shape of the all-solid-state battery include a coin type, a laminate type, a cylindrical type, and a square type.
The use of the all-solid-state battery is not particularly limited, but examples thereof include power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline-powered vehicles, and diesel-powered vehicles. In particular, the all-solid-state battery may be used as a driving power source for hybrid electric vehicles, plug-in hybrid electric vehicles, or electric vehicles. The all-solid-state battery of the present disclosure may also be used as a power source for moving objects other than vehicles (e.g., railways, ships, and aircraft), and may also be used as a power source for electrical products such as information processing devices.

Example 1
[Preparation of Positive Electrode Layer]
Using a tumbling fluidized coating device (manufactured by Powrex Corporation), positive electrode active material particles (particles having _Li1.15Ni1 / _{3Co1 /} 3Mn1 _{/ 3O2} as a main phase) were coated with lithium niobate in an air atmosphere, and then sintered in an air atmosphere to obtain positive electrode active material particles having a coating layer of lithium niobate.
PVdF, the above positive electrode active material particles, a sulfide-based solid electrolyte (Li ₂ S-P ₂ S ₅ -based glass ceramic), and VGCF (manufactured by Showa Denko K.K.) were added to a polypropylene container, and the resulting slurry for the positive electrode layer was stirred for 30 seconds with an ultrasonic dispersing device (UH-50 manufactured by SMT Corporation).
Next, the container was shaken for 3 minutes with a shaker (TTM-1 manufactured by Shibata Scientific Co., Ltd.), and the slurry for the positive electrode layer was further stirred for 30 seconds with an ultrasonic dispersing device. After shaking the container for 3 minutes with a shaker, the slurry for the positive electrode layer was applied to the aluminum foil by the blade method using an applicator. Thereafter, the slurry for the positive electrode layer was naturally dried, and dried for 30 minutes on a hot plate at 100 ° C. to obtain a positive electrode mixture on the aluminum foil (substrate). The laminate of the aluminum foil (substrate) and the positive electrode mixture was densified at 4 t / cm to obtain a positive electrode layer on the aluminum foil (substrate). The amount of the slurry for the positive electrode layer applied was adjusted so that the thickness of the positive electrode layer obtained when the positive electrode mixture was densified at 4 t / cm was 15 μm.

[Preparation of negative electrode]
PVdF, negative electrode active material particles (Li ₄ Ti ₅ O ₁₂ (LTO) particles), and the same sulfide-based solid electrolyte (Li ₂ S-P ₂ S ₅ -based glass ceramic) as above were added to a polypropylene container, and the obtained negative electrode layer slurry was stirred for 30 minutes with an ultrasonic dispersion device. The negative electrode layer slurry was applied to a copper foil by a blade method using an applicator. Thereafter, the negative electrode layer slurry was naturally dried and dried on a hot plate at 100 ° C. for 30 minutes to obtain a negative electrode having a negative electrode layer on a copper foil (negative electrode current collector). Thereafter, the negative electrode layer slurry was similarly applied to the back side of the copper foil (negative electrode current collector) and dried to form a negative electrode layer on the back side of the copper foil (negative electrode current collector).

[Preparation of solid electrolyte layer]
Heptane, BR, and a sulfide-based solid electrolyte (Li ₂ S-P ₂ S ₅ -based glass ceramic) were added to a polypropylene container, and the resulting solid electrolyte layer slurry was stirred for 30 seconds with an ultrasonic dispersion device. Next, the container was shaken for 30 minutes with a shaker (TTM-1 manufactured by Shibata Scientific Co., Ltd.), and the solid electrolyte layer slurry was further stirred for 30 seconds with an ultrasonic dispersion device. After shaking the container for 3 minutes with a shaker, the solid electrolyte layer slurry was applied onto an aluminum foil by a blade method using an applicator. Thereafter, the solid electrolyte layer slurry was naturally dried and dried on a hot plate at 100 ° C. for 30 minutes to form a solid electrolyte layer on the aluminum foil as a substrate.

[Preparation of Laminate]
(1) Laminated body obtaining process: A solid electrolyte layer was laminated on both sides of the negative electrode so that each negative electrode layer and each solid electrolyte layer were in direct contact with each other, and pressed at 1.6 t/cm, and then the aluminum foil substrate was peeled off from each solid electrolyte layer. Next, a positive electrode layer was laminated on each solid electrolyte layer so that each positive electrode layer and each solid electrolyte layer were in direct contact with each other, and pressed at 1.6 t/cm. Then, the aluminum foil substrate was peeled off from each positive electrode layer to obtain a laminate.

(2) Cutting Step The obtained laminate was pressed at 5 t/cm and 170°C.
Thereafter, the laminate was laser trimmed so that the positive electrode layer had a size of 70.0 mm × 71.0 mm, and the laminate was cut so that the negative electrode had a size of 72.0 mm × 72.0 mm. Then, a negative electrode terminal was welded to one side surface of the laminate.
FIG. 2 is a diagram showing an example of a laminate before a cutting process.
FIG. 3 is a diagram showing an example of a laminate after the cutting process.
As shown in FIG. 3, the laminate was cut along the cutting lines shown in FIG. 2 so that the side surface opposite to the side surface to which the negative electrode terminal was welded was flush with the positive electrode layer size of 70.0 mm × 70.0 mm, thereby obtaining a laminate having a total thickness of 130 μm.

4 is a diagram showing an outline of the (3) joint forming step and (4) bonding step of Example 1. 20 is a positive electrode current collector foil, 21 is double-sided tape No. 5605, 22 is Q51, 30 is a positive electrode layer, 40 is a laminate of solid electrolyte layer-negative electrode layer-negative electrode current collector+negative electrode terminal-negative electrode layer-solid electrolyte layer, 41 is a negative electrode terminal, and 50 is a laminate of positive electrode layer-solid electrolyte layer-negative electrode layer-negative electrode current collector+negative electrode terminal-negative electrode layer-solid electrolyte layer-positive electrode layer.
An insulating layer was prepared, which was a two-layer laminate (thickness 100 μm) of polyethylene naphthalate film Q51 (thickness 50 μm) manufactured by Teijin DiPont and double-sided tape No. 5605 (thickness 50 μm) manufactured by Nitto Denko Corporation, in which the depth of Q51 was greater than the depth of the positive electrode current collector foil, and the depth of double-sided tape No. 5605 was smaller than the depth of the positive electrode current collector foil. The thickness of the insulating layer (100 μm) was smaller than the thickness of the laminate (130 μm).
The insulating layer was cut to a width of 3 mm, and the insulating layer was attached to an area (position 70 to 72 mm in the surface direction from the negative electrode terminal side) adjacent to an area on the surface of the positive electrode current collector foil where the laminate was to be disposed so that the double-sided tape No. 5605 was in contact with the positive electrode current collector foil as a second current collector, thereby forming a joint body of the positive electrode current collector foil and the insulating layer.

(4) Adhesion process A hot melt material was applied onto the positive current collector foil. Then, on the surface of the positive current collector foil, the insulating layer (tape) was used as a reference for positioning the laminate, and the laminate was arranged in a region on the surface of the positive current collector foil where the laminate was to be arranged so that the second electrode layer was in contact with the positive current collector foil. The flush side of the laminate was brought into contact with the insulating layer, and the insulating layer and the flush side of the laminate were bonded together. These were then heated at 140° C., and the positive current collector foil and the laminate were bonded and fixed together with the hot melt material.
Thereafter, another positive electrode current collector foil was placed on the opposite side of the stacking direction to the positive electrode current collector foil side of the laminate via a hot melt material, and these were pressed together under conditions of 140°C and 5 MPa, the positive electrode terminal was welded, and then these were vacuum sealed to obtain an all-solid-state battery.
Thereafter, the resistance of the all-solid-state battery was measured to check whether or not a short circuit had occurred.

Example 2
5 is a diagram showing an outline of the (3) bonded body forming step and (4) bonding step of Example 2. The numbers in FIG. 5 have the same meanings as those in FIG.
In the above (3) joint formation step, an insulating layer was prepared which was a three-layer laminate (thickness 150 μm) of Nitto Denko double-sided tape No. 5605 (thickness 50 μm), Teijin DiPont polyethylene naphthalate film Q51 (thickness 50 μm), and Nitto Denko double-sided tape No. 5605 (thickness 50 μm), in which the depth of Q51 was greater than the depth of the positive electrode current collector foil, and the depth of double-sided tape No. 5605 was smaller than the depth of the positive electrode current collector foil. The thickness of the insulating layer (150 μm) was greater than the thickness of the laminate (130 μm).
An all-solid-state battery was obtained in the same manner as in Example 1, except that the insulating layer was cut to a width of 3 mm, and the insulating layer was attached to an area adjacent to an area on the surface of the positive electrode current collector foil where the laminate was to be placed so that one double-sided tape No. 5605 was in contact with the positive electrode current collector foil as a second current collector, thereby forming a bonded body of the positive electrode current collector foil and the insulating layer.

Example 3
6 is a diagram showing an outline of (3) the bonded body forming step and (4) the bonding step in Example 3. 23 indicates Hibon ZH234-1, and the other numerals in FIG. 6 have the same meanings as in FIG.
In the above (3) bonded body forming step, the insulating layer was prepared by pressing Hitachi Chemical's Hibon ZH234-1 together with a spacer having a thickness of 140 μm at a temperature of 120° C. The thickness of the insulating layer (140 μm) was greater than the thickness of the laminate (130 μm).
The insulating layer was cut to a width of 3 mm, and the insulating layer was attached to a region adjacent to the region on the surface of the positive electrode current collector foil where the laminate was to be placed, using a butyl butyrate solution containing PVDF as a binder, to form a bonded body of the positive electrode current collector foil and the insulating layer. Except for this, an all-solid-state battery was obtained in the same manner as in Example 1.

(Comparative Example 1)
7 is a diagram showing an outline of the (3) bonded body forming step and (4) bonding step of Comparative Example 1. The numbers in FIG. 7 have the same meanings as those in FIG.
In the above (4) bonding step, a position 1 mm from the end of the positive electrode layer on the negative electrode terminal side of the laminate toward the center in the surface direction was set as a reference position for laminating with the positive electrode current collector, and the laminate was placed on the positive electrode current collector foil so that the region from the end of the positive electrode layer on the negative electrode terminal side of the laminate toward the center in the surface direction of 1 mm did not face the positive electrode current collector foil, and the positive electrode current collector foil and the laminate were fixed. That is, in the above (3) joining step, a part of the insulating layer (1 mm wide) was placed in the region on the surface of the positive electrode current collector foil where the laminate was to be placed (at a position 69 to 71 mm from the negative electrode terminal side, not at a position 70 to 72 mm in the surface direction). Except for this, an all-solid-state battery was obtained in the same manner as in Example 1.

(Comparative Example 2)
8 is a diagram showing an outline of the (3) bonded body forming step and (4) bonding step of Comparative Example 2. The numbers in FIG. 8 have the same meanings as those in FIG.
In the above (4) bonding step, a position 2 mm from the end of the positive electrode layer on the negative electrode terminal side of the laminate toward the center in the surface direction was set as a reference position for laminating with the positive electrode current collector, and the laminate was placed on the positive electrode current collector foil so that the region from the end of the positive electrode layer on the negative electrode terminal side of the laminate toward the center in the surface direction of 2 mm did not face the positive electrode current collector foil, and the positive electrode current collector foil and the laminate were fixed. That is, in the above (3) joining step, a part of the insulating layer (2 mm wide) was placed in the region on the surface of the positive electrode current collector foil where the laminate was to be placed (68 to 70 mm from the negative electrode terminal side, not 70 to 72 mm in the surface direction). Except for this, an all-solid-state battery was obtained in the same manner as in Example 1.

[Evaluation method]
Ten samples of each of the all-solid-state batteries of Examples 1 to 3 and Comparative Examples 1 and 2 were prepared, and the resistance of each was measured to confirm the number of samples in which a short circuit occurred and the number of samples in which an overlap between the positive electrode layer and the insulating layer occurred. These results are shown in Table 1.

[Evaluation Results]
As shown in Table 1, it can be seen that no short circuit occurs and no overlapping of the positive electrode layer and the insulating layer occurs in the all-solid-state batteries of Examples 1 to 3. Therefore, according to the manufacturing method of the present disclosure, it is possible to improve the energy density of the all-solid-state battery.

11 First current collector 12 First electrode layer 13 Solid electrolyte layer 14 Second electrode layer 15 Second current collector 16 Insulating layer 20 Positive electrode current collector foil 21 Double-sided tape No. 5605
22 Q51
23 Hibon ZH234-1
30 Positive electrode layer 40 Laminated body of solid electrolyte layer-negative electrode layer-negative electrode current collector+negative electrode terminal-negative electrode layer-solid electrolyte layer 41 Negative electrode terminal 50 Laminated body of positive electrode layer-solid electrolyte layer-negative electrode layer-negative electrode current collector+negative electrode terminal-negative electrode layer-solid electrolyte layer-positive electrode layer

Claims (1)

A method for producing an all-solid-state battery having a first electrode layer, a solid electrolyte layer, a second electrode layer, and a second current collector, in this order, on both sides of a first current collector, the method comprising the steps of:
obtaining a laminate in which the first electrode layer, the solid electrolyte layer, and the second electrode layer are laminated in this order on both sides of the first current collector;
A step of cutting at least one side surface of the laminate in the lamination direction to make the surface flush;
disposing an insulating layer on a surface of the second current collector in an area adjacent to an area where the laminate is to be disposed, thereby forming a bonded body of the second current collector and the insulating layer;
disposing the laminate in a region on a surface of the second current collector where the laminate is to be disposed such that an entire region of a surface of the second electrode layer facing the second current collector is in contact with the second current collector , and bonding the insulating layer to a side surface of the laminate that is flush with the surface of the laminate.