All-solid-state battery and method for manufacturing the same

Abstract

To provide an all-solid-state battery having a multi-layered solid electrolyte layer, which can improve battery performance by improving interface bonding.SOLUTION: An all-solid-state battery in which a positive electrode layer and a negative electrode layer are stacked with a solid electrolyte layer interposed therebetween includes a first solid electrolyte layer pressure-bonded to the positive electrode layer, a third solid electrolyte layer pressure-bonded to the negative electrode layer, and a second solid electrolyte layer bonding the first solid electrolyte layer and the third solid electrolyte layer together, and the particle size of the solid electrolyte particles constituting the second solid electrolyte layer is smaller than the particle size of the solid electrolyte particles constituting the first solid electrolyte layer and the third solid electrolyte layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an all-solid-state battery and a method for manufacturing an all-solid-state battery. [Background technology]

[0002] In recent years, research and development has been conducted on secondary batteries that contribute to energy efficiency, in order to ensure that more people have access to affordable, reliable, sustainable, and advanced energy. Among secondary batteries, all-solid-state batteries that use a solid electrolyte as the electrolyte are attracting particular attention because they are highly safe due to the non-flammable nature of the solid electrolyte and have higher energy density. As an all-solid-state battery, all-solid-state batteries having a layered structure in which multiple positive electrode layers and negative electrode layers are alternately stacked with solid electrolyte layers interposed therebetween are being studied (for example, Patent Document 1).

[0003] On the other hand, it has been proposed to make the solid electrolyte layer in an all-solid-state battery multi-layered (two-layered) (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2022 / 158226 [Patent Document 2] International Publication No. 2014 / 010043 Summary of the Invention [Problem to be solved by the invention]

[0005] The technology disclosed in Patent Document 2 mainly relates to a technology for forming a two-layer solid electrolyte layer, but the current situation is that technology for ensuring interfacial bonding and improving battery performance such as battery capacity and cycle characteristics when forming a multi-layer solid electrolyte layer has not been fully explored. For example, in order to improve the density of each layer, it is possible to pre-pressure-bond the positive electrode layer and the solid electrolyte layer, but the surface of the solid electrolyte layer that has undergone such pressure bonding is flattened, which tends to deteriorate the bonding with other layers. Therefore, there has been a need for a technology for forming a multi-layer solid electrolyte layer while ensuring the bonding of each layer that constitutes an all-solid-state battery.

[0006] The present invention has been made in view of the above, and an object of the present invention is to provide an all-solid-state battery having a multilayered solid electrolyte layer, which can improve the battery performance by improving the interfacial bonding property. [Means for solving the problem]

[0007] (1) An all-solid-state battery in which a positive electrode layer and a negative electrode layer are stacked with a solid electrolyte layer interposed therebetween, the all-solid-state battery comprising: a first solid electrolyte layer pressure-bonded to the positive electrode layer; a third solid electrolyte layer pressure-bonded to the negative electrode layer; and a second solid electrolyte layer bonding the first solid electrolyte layer and the third solid electrolyte layer together, wherein the particle size of the solid electrolyte particles constituting the second solid electrolyte layer is smaller than the particle size of the solid electrolyte particles constituting the first solid electrolyte layer and the third solid electrolyte layer.

[0008] According to the invention (1), it is possible to provide an all-solid-state battery capable of improving battery performance by improving interface bonding.

[0009] (2) The all-solid-state battery according to (1), wherein the first solid electrolyte layer, the second solid electrolyte layer, and the third solid electrolyte layer are made of the same material.

[0010] According to the invention (2), the interface bondability can be more preferably improved.

[0011] (3) The all-solid-state battery according to (1) or (2), wherein the interfaces of the second solid electrolyte layer with the first solid electrolyte layer and the third solid electrolyte layer extend into the first solid electrolyte layer side and the third solid electrolyte layer side.

[0012] According to the invention (3), the interface bondability can be more preferably improved.

[0013] (4) The all-solid-state battery according to any one of (1) to (3), wherein the particle size D50 of the solid electrolyte particles constituting the second solid electrolyte layer is equal to or less than half the particle size D50 of the solid electrolyte particles constituting the first solid electrolyte layer and the particle size D50 of the solid electrolyte particles constituting the third solid electrolyte layer.

[0014] According to the invention (4), the interface bondability can be more preferably improved.

[0015] (5) The all-solid-state battery according to any one of (1) to (4), wherein the materials constituting the first solid electrolyte layer, the second solid electrolyte layer, and the third solid electrolyte layer are a sulfide-based solid electrolyte and at least one of a polyvinylidene fluoride binder and a styrene butadiene binder; the particle diameters D10, D50, and D95 ​​of the solid electrolyte particles constituting the first solid electrolyte layer and the third solid electrolyte layer are 0.4 μm, 0.7 μm, and 1.7 μm, respectively; and the particle diameter D50 of the solid electrolyte particles constituting the second solid electrolyte layer is 0.2 μm.

[0016] According to the invention (5), the interface bondability can be more preferably improved.

[0017] (6) The all-solid-state battery according to any one of (1) to (5), wherein the second solid electrolyte layer includes solid electrolyte particles and a substrate, and the diameter of the substrate is smaller than the diameter of the solid electrolyte particles.

[0018] According to the invention (6), the interface bondability can be more preferably improved.

[0019] (7) An all-solid-state battery in which a positive electrode layer and a negative electrode layer are stacked with a solid electrolyte layer interposed therebetween, the all-solid-state battery comprising: a first solid electrolyte layer pressure-bonded to the positive electrode layer; a third solid electrolyte layer disposed on the negative electrode layer side; and a second solid electrolyte layer bonding the first solid electrolyte layer and the third solid electrolyte layer together, wherein the particle size of the solid electrolyte particles constituting the second solid electrolyte layer is smaller than the particle size of the solid electrolyte particles constituting the first solid electrolyte layer and the third solid electrolyte layer.

[0020] According to the seventh aspect of the present invention, an all-solid-state battery can be provided that can improve the battery performance by improving the interface bonding property.

[0021] (8) The all-solid-state battery according to any one of (1) to (7), wherein another layer is disposed between the anode layer and the third solid electrolyte layer, and the third solid electrolyte layer is bonded to the another layer.

[0022] According to the invention (8), the interface bondability can be more preferably improved.

[0023] (9) A method for manufacturing an all-solid-state battery in which a positive electrode layer and a negative electrode layer are stacked with a solid electrolyte layer interposed therebetween, the method comprising: a first pressure bonding step of pressurizing and bonding layers including the positive electrode layer and a first solid electrolyte layer to manufacture a first laminate; a second pressure bonding step of pressurizing and bonding layers including the negative electrode layer and a third solid electrolyte layer to manufacture a second laminate; a step of arranging unpressurized solid electrolyte particles between the first solid electrolyte layer and the third solid electrolyte layer to form a second solid electrolyte layer; and a third pressure bonding step of pressurizing and bonding the first laminate and the second laminate with the second solid electrolyte layer interposed therebetween, wherein the particle size of the solid electrolyte particles constituting the second solid electrolyte layer is smaller than the particle size of the solid electrolyte particles constituting the first solid electrolyte layer and the third solid electrolyte layer.

[0024] According to the invention of (9), it is possible to manufacture an all-solid-state battery capable of improving battery performance by improving the interface bonding property.

[0025] (10) The method for producing an all-solid-state battery according to (9), wherein the first solid electrolyte layer, the second solid electrolyte layer, and the third solid electrolyte layer are made of the same material.

[0026] According to the invention (10), the interface bondability can be more preferably improved.

[0027] (11) The method for producing an all-solid-state battery according to (9) or (10), wherein the interfaces of the second solid electrolyte layer, which has been subjected to the third pressure bonding step, with the first solid electrolyte layer and the third solid electrolyte layer extend into the first solid electrolyte layer side and the third solid electrolyte layer side.

[0028] According to the invention (11), the interface bondability can be more preferably improved.

[0029] (12) The method for producing an all-solid-state battery according to any one of (9) to (11), wherein the particle size D50 of the solid electrolyte particles constituting the second solid electrolyte layer is equal to or less than half the particle size D50 of the solid electrolyte particles constituting the first solid electrolyte layer and the particle size D50 of the solid electrolyte particles constituting the third solid electrolyte layer.

[0030] According to the invention (12), the interface bondability can be more preferably improved.

[0031] (13) The method for producing an all-solid-state battery according to any one of (9) to (12), wherein materials constituting the first solid electrolyte layer, the second solid electrolyte layer, and the third solid electrolyte layer are a sulfide-based solid electrolyte and at least one of a polyvinylidene fluoride-based binder and a styrene butadiene-based binder; the solid electrolyte particles constituting the first solid electrolyte layer and the third solid electrolyte layer have a particle size D10 of 0.4 μm, a particle size D50 of 0.7 μm, and a particle size D95 of 1.7 μm; and the solid electrolyte particles constituting the second solid electrolyte layer have a particle size D50 of 0.2 μm.

[0032] According to the invention (13), the interface bondability can be more preferably improved.

[0033] (14) The method for producing an all-solid-state battery according to any one of (9) to (13), wherein the second solid electrolyte layer includes solid electrolyte particles and a substrate, and a diameter of the substrate is smaller than a diameter of the solid electrolyte particles.

[0034] According to the invention (14), the interface bondability can be more preferably improved.

[0035] (15) A method for manufacturing an all-solid-state battery in which a positive electrode layer and a negative electrode layer are stacked with a solid electrolyte layer interposed therebetween, the method comprising: a first pressure bonding step of manufacturing a first laminate by pressure bonding layers including the positive electrode layer and a first solid electrolyte layer; a step of manufacturing a second laminate by arranging a third solid electrolyte layer on the negative electrode layer side; a step of arranging unpressurized solid electrolyte particles between the first solid electrolyte layer and the third solid electrolyte layer to form a second solid electrolyte layer; and a third pressure bonding step of pressure bonding the first laminate and the second laminate with the second solid electrolyte layer interposed therebetween, wherein the particle size of the solid electrolyte particles constituting the second solid electrolyte layer is smaller than the particle size of the solid electrolyte particles constituting the first solid electrolyte layer and the third solid electrolyte layer.

[0036] According to the invention of (15), an all-solid-state battery capable of improving battery performance can be manufactured by improving the interface bonding property.

[0037] (16) The method for producing an all-solid-state battery according to any one of (9) to (15), further comprising a step of disposing another layer between the negative electrode layer and the third solid electrolyte layer, wherein the third solid electrolyte layer is bonded to the another layer.

[0038] According to the invention (16), the interface bondability can be more preferably improved. [Brief explanation of the drawings]

[0039] [Figure 1] FIG. 1 is a schematic cross-sectional view showing an all-solid-state battery according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view showing an interface of a solid electrolyte layer according to one embodiment of the present invention. [Figure 3] FIG. 10 is a schematic cross-sectional view showing an interface of a solid electrolyte layer according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0040] [All-solid battery] The all-solid-state battery 1 has a structure in which a positive electrode layer and a negative electrode layer are stacked with a solid electrolyte layer interposed therebetween. As shown in Fig. 1, the all-solid-state battery 1 has an electrode stack in which a negative electrode layer 2, solid electrolyte layers 41, 42, and 43, and a positive electrode layer 3 are stacked in this order. The structure of the all-solid-state battery 1 is not limited to the above, and it is sufficient that the negative electrode layer 2 and the positive electrode layer 3 are stacked with three solid electrolyte layers 41, 42, and 43 interposed therebetween, and the number of layers is not particularly limited.

[0041] The solid electrolyte layer in the all-solid-state battery 1 includes a first solid electrolyte layer 41 disposed on the cathode layer 3 side, a third solid electrolyte layer 43 disposed on the anode layer 2 side, and a second solid electrolyte layer 42 disposed between the first solid electrolyte layer 41 and the third solid electrolyte layer 43. Another layer such as an intermediate layer may be optionally laminated between the anode layer 2 and the third solid electrolyte layer 43.

[0042] The all-solid-state battery 1 is not particularly limited, but may be a lithium-ion solid-state secondary battery or a lithium metal secondary battery.

[0043] (negative electrode layer) The anode layer 2 has an anode active material layer 22 and an anode current collector layer 21. The anode active material layer 22 is not particularly limited and can be made of a material that can be used as an anode active material for a solid-state battery. An example of the anode active material layer 22 is a lithium metal layer. The lithium metal may contain a lithium alloy or the like in addition to the lithium metal itself. The anode active material layer 22 may contain silicon-based active materials such as Si and Si alloys, lithium titanate (Li4Ti5O 12The electrode may be composed of lithium transition metal oxides such as TiO2, Nb2O3 and WO3, metal sulfides, metal nitrides, carbon materials such as graphite, soft carbon and hard carbon, metallic indium, etc.

[0044] The negative electrode active material layer 22 may contain other materials that can be contained in the negative electrode active material layer of a solid-state battery. Examples of such materials include a solid electrolyte, a conductive additive, and a binder. Examples of the solid electrolyte include the same solid electrolyte contained in the solid electrolyte layer described below. Examples of the conductive additive include carbon black, natural graphite, carbon fiber, and carbon nanotubes. Examples of the binder include a nitrile-based binder, a polyester-based binder, an acrylic acid-based binder, a cellulose-based binder, a styrene-based binder, a styrene-butadiene-based binder, a vinyl acetate-based binder, a urethane-based binder, a fluoroethylene-based binder, and a polyvinylidene fluoride-based binder.

[0045] The negative electrode current collector layer 21 is not particularly limited, but may be made of copper, nickel, stainless steel, or the like. Examples of the shape of the negative electrode current collector layer 21 include foil, plate, mesh, nonwoven fabric, and foam. A portion of the negative electrode current collector layer 21 extends in a predetermined direction to form a negative electrode current collector tab.

[0046] (positive electrode layer) The positive electrode layer 31 has a positive electrode active material layer and a positive electrode current collector layer. The positive electrode active material layer is not particularly limited and can be made of a material that can be used as a positive electrode active material for a solid-state battery. Examples of positive electrode active materials that make up the positive electrode active material layer 31 include LiCoO2, LiNiO2, LiCo x Ni y Mn z O2 (x+y+z=1), LiVO2, LiCrO2, etc., layered positive electrode active material particles, LiMn2O4, Li(Ni 0.25 Mn 0.75Examples of such positive electrode active materials include spinel-type positive electrode active materials such as LiCoPO, LiMnPO, and LiFePO; solid solution oxides (LiMnO-LiMO (M=Co, Ni, etc.)); conductive polymers such as polyaniline and polypyrrole; sulfides such as LiS, CuS, Li-Cu-S compounds, TiS, FeS, MoS, and Li-Mo-S compounds; and mixtures of sulfur and carbon. The positive electrode active material may be one of the above materials, or may be composed of two or more of the above materials.

[0047] The positive electrode current collector layer is not particularly limited, but may be made of, for example, aluminum, stainless steel, conductive carbon (graphite, carbon nanotubes, etc.), etc. Examples of the shape of the positive electrode current collector layer include foil, plate, mesh, nonwoven fabric, and foam. A portion of the positive electrode current collector layer extends in a predetermined direction to form a positive electrode current collector tab.

[0048] (solid electrolyte layer) The solid electrolyte layers 41, 42, and 43 are formed between the anode layer 2 and the cathode layer 3. In this embodiment, the first solid electrolyte layer 41, which is disposed on the cathode layer side, the second solid electrolyte layer 42, and the third solid electrolyte layer 43, which is disposed on the anode layer side, are stacked in this order. The first solid electrolyte layer 41 is pressure-bonded to the cathode layer 3, and the third solid electrolyte layer 43 is pressure-bonded to the anode layer 2. The second solid electrolyte layer 42 is a layer that bonds the first solid electrolyte layer 41 and the third solid electrolyte layer 43.

[0049] The first solid electrolyte layer 41 is pressure-bonded to the positive electrode layer 3. Therefore, the interface of the first solid electrolyte layer 41 on the second solid electrolyte layer 42 side is compressed in a substantially flat state (existing only unevenness corresponding to the particle diameter of the solid electrolyte particles).

[0050] The solid electrolyte material constituting the first solid electrolyte layer 41 is not particularly limited, and may be any material that can be used as an electrolyte in a solid-state battery. Examples include inorganic solid electrolytes such as sulfide-based solid electrolytes, oxide-based solid electrolytes, halide-based solid electrolytes, and lithium-containing salts, as well as polymer-based solid electrolytes such as polyethylene oxide. In particular, it is preferable to use a sulfide-based solid electrolyte. The above solid electrolytes may be used alone or in combination of two or more.

[0051] The solid electrolyte material constituting first solid electrolyte layer 41 is in the form of particles. The particle size D10 (median size) of the solid electrolyte particles constituting first solid electrolyte layer 41 is preferably 0.3 μm to 0.5 μm. The particle size D50 (median size) is preferably 0.5 μm to 1.0 μm. The particle size D95 (median size) is preferably 1.5 μm to 2.0 μm.

[0052] In addition to the solid electrolyte material, the first solid electrolyte layer 41 may contain a material that can be used in a solid electrolyte layer of a solid-state battery. For example, the first solid electrolyte layer 41 may contain a binder. Examples of binders include nitrile-based binders, polyester-based binders, acrylic acid-based binders, cellulose-based binders, styrene-butadiene-based binders, vinyl acetate-based binders, urethane-based binders, fluoroethylene-based binders, and polyvinylidene fluoride-based binders. In particular, it is preferable that the first solid electrolyte layer 41 contains at least one of a polyvinylidene fluoride-based binder and a styrene-butadiene-based binder.

[0053] The third solid electrolyte layer 43 is disposed on the anode layer 2 side. The third solid electrolyte layer 43 may be pressure-bonded to the anode layer 2. When an intermediate layer is provided between the anode layer 2 and the third solid electrolyte layer 43, the third solid electrolyte layer 43 may be pressure-bonded to the anode layer 2 via the intermediate layer. The other configuration of the third solid electrolyte layer 43 may be the same as that of the first solid electrolyte layer 41.

[0054] The intermediate layer is disposed between the anode layer 2 and the third solid electrolyte layer 43. For example, when the all-solid-state battery 1 is a lithium metal battery, the intermediate layer has the function of uniformly depositing lithium metal. Therefore, the interface between the intermediate layer and the third solid electrolyte layer 43 is stabilized. When the all-solid-state battery 1 is a lithium metal secondary battery having an intermediate layer, the all-solid-state battery 1 may be an anode-free battery in which the anode active material layer 22 is not present during the initial charge. In this case, a lithium metal layer is formed as the anode active material layer 22 after the initial charge / discharge.

[0055] The material constituting the intermediate layer is not particularly limited, and examples thereof include metals capable of alloying with lithium and amorphous carbon. Examples of metals capable of alloying with lithium include tin (Sn), silicon (Si), zinc (Zn), magnesium (Mg), gold (Au), platinum (Pt), palladium (Pd), silver (Ag), aluminum (Al), bismuth (Bi), and antimony (Sb). The metal capable of alloying with lithium may be nanoparticles. Examples of amorphous carbon include carbon blacks such as acetylene black, furnace black, and ketjen black, coke, and activated carbon. The amorphous carbon may be graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), CNT (carbon nanotube), fullerene, or graphene. The intermediate layer may contain a binder in addition to the above materials.

[0056] The second solid electrolyte layer 42 bonds the first solid electrolyte layer 41 and the third solid electrolyte layer 43. The particle size (e.g., median diameter D50) of the solid electrolyte particles constituting the second solid electrolyte layer 42 is smaller than the particle sizes of the first solid electrolyte layer 41 and the third solid electrolyte layer 43. This allows the particles constituting the second solid electrolyte layer 42 to penetrate into the interfaces with the first solid electrolyte layer 41 and the third solid electrolyte layer 43, thereby achieving favorable bonding. Hereinafter, a description will be given with reference to the drawings.

[0057] Fig. 2 is a diagram showing a schematic diagram of the interface between the second solid electrolyte layer 42 and the third solid electrolyte layer 43. In Fig. 2, the solid electrolyte particles 42a constituting the second solid electrolyte layer 42 are smaller than the solid electrolyte particles 43a constituting the third solid electrolyte layer 43. In the example of Fig. 2, the particle size of the solid electrolyte particles 42a is half or less the particle size of the solid electrolyte particles 43a.

[0058] In contrast, FIG. 3 illustrates an example in which the particle diameters of the solid electrolyte particles 42b constituting the second solid electrolyte layer 42 are approximately the same as those of the solid electrolyte particles 43a constituting the third solid electrolyte layer 43. Comparing FIG. 2 and FIG. 3, in FIG. 3, two solid electrolyte particles 42b contact one solid electrolyte particle 43a at contact point P2, whereas in FIG. 2, two solid electrolyte particles 42a contact one solid electrolyte particle 43a at contact point P1. That is, by setting the particle diameter of the solid electrolyte particles 42a to be half or less of the particle diameter of the solid electrolyte particles 43a, the number of contact points can be increased by 1.5 times. Furthermore, compared to the example in FIG. 3, in the example in FIG. 2, the interfacial bonding area S1 is larger than S2. This improves the bonding strength between the second solid electrolyte layer 42 and the third solid electrolyte layer 43.

[0059] As shown in FIG. 2, the solid electrolyte particles 42a constituting the second solid electrolyte layer 42 penetrate into the interface side of the third solid electrolyte layer 43. Specifically, in the configuration of FIG. 2, compared to the configuration of FIG. 3, the penetration amount G1 is increased by approximately 40% compared to the penetration amount G2, and the bonded interface line length is increased by approximately 5%. The penetration amount refers to the difference (distance) between the average of the positions of the solid electrolyte particles 42a present at the interface with the third solid electrolyte layer 43 that penetrate furthest into the third solid electrolyte layer 43 and the average of the positions of the solid electrolyte particles 43a that penetrate furthest into the second solid electrolyte layer 42, as shown in FIGS. 2 and 3. The bonded interface line length refers to the length of the interfacial bonding areas S1 and S2 as viewed in cross section as shown in FIGS. 2 and 3. The configuration of FIG. 2 improves the bondability between the second solid electrolyte layer 42 and the third solid electrolyte layer 43.

[0060] In order to preferably obtain the effect of improving the bonding property, the particle size D50 (median size) of the solid electrolyte particles constituting the second solid electrolyte layer 42 is preferably 0.2 μm to 0.3 μm.

[0061] The second solid electrolyte layer 42 may also include a base material that can be filled with a solid electrolyte. The base material is not particularly limited, but may be, for example, a nonwoven fabric. When the second solid electrolyte layer 42 includes a base material, the diameter (fiber diameter) of the base material is preferably smaller than the particle diameter of the solid electrolyte particles that make up the second solid electrolyte layer 42.

[0062] 2 and 3 show the interface between the second solid electrolyte layer 42 and the third solid electrolyte layer 43 as an example, the same applies to the interface between the second solid electrolyte layer 42 and the first solid electrolyte layer 41.

[0063] In this embodiment, the first solid electrolyte layer 41, the second solid electrolyte layer 42, and the third solid electrolyte layer 43 are made of the same solid electrolyte material. This allows for improved bonding between the layers. However, the type and content of the binder and the presence or absence of a base material may differ.

[0064] [Manufacturing method for all-solid-state batteries] The method for manufacturing the all-solid-state battery according to this embodiment includes a first pressure bonding step of manufacturing a first laminate L1 by pressure bonding layers including a positive electrode layer 3 and a first solid electrolyte layer 41, a step of manufacturing a second laminate L2 by arranging a third solid electrolyte layer 43 on the negative electrode layer 2 side, a step of arranging unpressurized solid electrolyte particles between the first solid electrolyte layer 41 and the third solid electrolyte layer 43 to form a second solid electrolyte layer 42, and a third pressure bonding step of pressure bonding the first laminate L1 and the second laminate L2 via the second solid electrolyte layer 42.

[0065] The first pressure bonding step is a step of pressure bonding a layer including the positive electrode active material layer side of the positive electrode layer 3 and the first solid electrolyte layer 41. The pressing pressure in the first pressure bonding step can be, for example, 600 MPa to 1200 MPa.

[0066] The step of disposing the third solid electrolyte layer 43 on the anode layer 2 side may be a second pressure bonding step of producing a second laminate L2 by pressure bonding a layer including the anode layer 2 and the third solid electrolyte layer 43. Alternatively, another layer such as an intermediate layer may be disposed between the anode layer 2 and the third solid electrolyte layer 43. The pressing pressure in the second pressure bonding step may be, for example, 300 MPa to 800 MPa.

[0067] The step of forming the second solid electrolyte layer 42 is a step of disposing unpressurized solid electrolyte particles between the first solid electrolyte layer 41 of the first laminate L1 obtained as described above and the third solid electrolyte layer 43 of the second laminate L2. A mixture of unpressurized solid electrolyte particles and materials constituting the second solid electrolyte layer, such as a base material and a binder, may be used.

[0068] In the process of forming the second solid electrolyte layer 42, by not applying pressure to the solid electrolyte particles to be arranged, it is possible to have unevenness on the surface that is equal to or larger than the particle size of the solid electrolyte particles. Furthermore, by not applying pressure, the Young's modulus is also low.

[0069] The first laminate L1 and the second laminate L2 are bonded together in the third pressure bonding step. The pressure applied in the third pressure bonding step may be, for example, 300 MPa to 800 MPa.

[0070] As described above, the particle size of the solid electrolyte particles constituting second solid electrolyte layer 42 is smaller than the particle size of the solid electrolyte particles constituting first solid electrolyte layer 41 and third solid electrolyte layer 43, and therefore the particles can penetrate into the interface, improving the interfacial bonding. Furthermore, even if the pressing pressure in the third pressure bonding step is reduced, the density of second solid electrolyte layer 42 can be increased, i.e., the resistance can be reduced.

[0071] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. The all-solid-state battery 1 may have a structure that can be used in a solid-state battery, such as an exterior body, other than the laminated structure shown in FIG. [Explanation of symbols]

[0072] 1. All-solid-state battery (layer structure of all-solid-state battery) 2. Negative electrode layer 3 Positive electrode layer 41 First solid electrolyte layer 42 Second solid electrolyte layer 43 Third solid electrolyte layer L1 First laminate L2 Second laminate

Claims

1. A method for manufacturing an all-solid-state battery in which a positive electrode layer and a negative electrode layer are stacked with a solid electrolyte layer interposed therebetween, a first pressure bonding step of pressure bonding a layer including the positive electrode layer and a first solid electrolyte layer to manufacture a first laminate; a second pressure bonding step of pressure bonding a layer including the negative electrode layer and a third solid electrolyte layer to manufacture a second laminate; disposing unpressurized solid electrolyte particles between the first solid electrolyte layer and the third solid electrolyte layer to form a second solid electrolyte layer; a third pressure bonding step of pressure bonding the first stack and the second stack together via the second solid electrolyte layer, a particle size of the solid electrolyte particles constituting the second solid electrolyte layer being smaller than a particle size of the solid electrolyte particles constituting the first solid electrolyte layer and the third solid electrolyte layer.

2. 2. The method for producing an all-solid-state battery according to claim 1, wherein the first solid electrolyte layer, the second solid electrolyte layer, and the third solid electrolyte layer are made of the same material.

3. 2. The method for manufacturing an all-solid-state battery according to claim 1, wherein interfaces of the second solid electrolyte layer, which has been subjected to the third pressure bonding step, with the first solid electrolyte layer and the third solid electrolyte layer extend into the first solid electrolyte layer side and the third solid electrolyte layer side.

4. The particle diameter D50 of the solid electrolyte particles constituting the second solid electrolyte layer is 2. The method for producing an all-solid-state battery according to claim 1, wherein the particle size D50 of the solid electrolyte particles constituting the first solid electrolyte layer and the particle size D50 of the solid electrolyte particles constituting the third solid electrolyte layer are equal to or less than half of each other.

5. the first solid electrolyte layer, the second solid electrolyte layer, and the third solid electrolyte layer are made of a material selected from the group consisting of a sulfide-based solid electrolyte, a polyvinylidene fluoride-based binder, and a styrene butadiene-based binder; the particle diameter D10 of the solid electrolyte particles constituting the first solid electrolyte layer and the third solid electrolyte layer is 0.4 μm, the particle diameter D50 is 0.7 μm, and the particle diameter D95 is 1.7 μm; 5. The method for producing an all-solid-state battery according to claim 4, wherein the particle diameter D50 of the solid electrolyte particles constituting the second solid electrolyte layer is 0.2 μm.

6. the second solid electrolyte layer includes solid electrolyte particles and a substrate, The method for producing an all-solid-state battery according to claim 1 , wherein a diameter of the substrate is smaller than a particle diameter of the solid electrolyte particles.

7. A method for manufacturing an all-solid-state battery in which a positive electrode layer and a negative electrode layer are stacked with a solid electrolyte layer interposed therebetween, a first pressure bonding step of pressure bonding a layer including the positive electrode layer and a first solid electrolyte layer to manufacture a first laminate; a step of disposing a third solid electrolyte layer on the negative electrode layer side to produce a second laminate; disposing unpressurized solid electrolyte particles between the first solid electrolyte layer and the third solid electrolyte layer to form a second solid electrolyte layer; a third pressure bonding step of pressure bonding the first stack and the second stack together via the second solid electrolyte layer, a particle size of the solid electrolyte particles constituting the second solid electrolyte layer being smaller than a particle size of the solid electrolyte particles constituting the first solid electrolyte layer and the third solid electrolyte layer.

8. disposing another layer between the anode layer and the third solid electrolyte layer; 8. The method for manufacturing an all-solid-state battery according to claim 1, wherein the third solid electrolyte layer is bonded to the other layer.

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