All-solid-state battery and method for manufacturing all-solid-state battery

Abstract

The problem to be solved by the present invention is to provide an all-solid-state battery having a multilayer solid electrolyte layer and capable of improving battery performance by improving interfacial adhesiveness. In order to solve the problem, the present invention provides an all-solid-state battery in which a positive electrode layer and a negative electrode layer are laminated with a solid electrolyte layer interposed therebetween, the all-solid-state battery comprising: a first solid electrolyte layer laminated to the positive electrode layer; the third solid electrolyte layer is laminated with the negative electrode layer; and a second solid electrolyte layer joining the first solid electrolyte layer and the third solid electrolyte layer, 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.

Description

Technical Field

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

[0002] In recent years, research and development has been underway on secondary batteries that contribute to energy efficiency, aiming to ensure more people have access to affordable, reliable, sustainable, and advanced energy. All-solid-state batteries, which use solid electrolytes as electrolytes in secondary batteries, have attracted particular attention due to their high safety and higher energy density, as solid electrolytes are non-flammable. Research is underway on all-solid-state batteries with a laminated structure consisting of multiple positive and negative electrode layers alternately laminated with solid electrolyte layers interposed therebetween (e.g., Patent Document 1).

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

[0004] [Prior Art Literature]

[0005] (Patent Document)

[0006] Patent Document 1: U.S. Patent Application Publication No. 2022 / 158226

[0007] Patent Document 2: International Publication No. 2014 / 010043 Summary of the Invention

[0008] [Problems to be solved by the invention]

[0009] The technology disclosed in patent document 2 mainly relates to a technology for making a solid electrolyte layer into two layers, but the current situation is that the following technology has not been fully studied: when the solid electrolyte layer is made into a multilayer, the adhesion of the interface is ensured, and the battery performance such as battery capacity or cycle characteristics is improved. For example, in order to increase the density of each layer, it is considered to press the positive electrode layer and the solid electrolyte layer in advance, but the surface of the solid electrolyte layer after such pressing is flattened, and as a result, there is a trend of deterioration in the adhesion with other layers. Therefore, it is desired to have a technology that makes the solid electrolyte layer into a multilayer while ensuring the adhesion of each layer constituting an all-solid-state battery.

[0010] The present invention has been made in view of the above, and an object thereof is to provide an all-solid-state battery having a multilayered solid electrolyte layer capable of improving battery performance by enhancing interfacial bonding.

[0011] [Technical means to solve the problem]

[0012] (1) An all-solid-state battery, which is formed by laminating a positive electrode layer and a negative electrode layer with a solid electrolyte layer interposed therebetween, and comprises: a first solid electrolyte layer laminated to the positive electrode layer; a third solid electrolyte layer laminated to the negative electrode layer; and a second solid electrolyte layer connecting the first solid electrolyte layer and the third solid electrolyte layer; 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.

[0013] According to the invention of (1), an all-solid-state battery can be provided, which can improve battery performance by improving interface bonding properties.

[0014] (2) The all-solid-state battery according to (1), wherein the materials constituting the first solid electrolyte layer, the second solid electrolyte layer, and the third solid electrolyte layer are the same material.

[0015] According to the invention of (2), the interface bonding properties can be further improved.

[0016] (3) An all-solid-state battery according to (1) or (2), wherein the interface between the second solid electrolyte layer and the first solid electrolyte layer and the third solid electrolyte layer extends into the first solid electrolyte layer side and the third solid electrolyte layer side.

[0017] According to the invention of (3), the interface bonding properties can be further improved.

[0018] (4) An all-solid-state battery according to any one of (1) to (3), wherein the particle size D50 of the solid electrolyte particles constituting the aforementioned second solid electrolyte layer is less than 1 / 2 of the particle size D50 of the solid electrolyte particles constituting the aforementioned first solid electrolyte layer and the particle size D50 of the solid electrolyte particles constituting the aforementioned third solid electrolyte layer.

[0019] According to the invention of (4), the interface bonding properties can be further improved.

[0020] (5) An all-solid-state battery according to any one of (1) to (4), wherein the materials constituting the aforementioned first solid electrolyte layer, the aforementioned second solid electrolyte layer and the aforementioned third solid electrolyte layer are sulfide solid electrolytes, and at least one of polyvinylidene fluoride adhesives and styrene butadiene adhesives, the particle size D10 of the solid electrolyte particles constituting the aforementioned first solid electrolyte layer and the aforementioned third solid electrolyte layer is 0.4 μm, the particle size D50 is 0.7 μm, and the particle size D95 is 1.7 μm, and the particle size D50 of the solid electrolyte particles constituting the aforementioned second solid electrolyte layer is 0.2 μm.

[0021] According to the invention of (5), the interface bonding properties can be further improved.

[0022] (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 particle size of the solid electrolyte particles.

[0023] According to the invention of (6), the interface bonding properties can be further improved.

[0024] (7) An all-solid-state battery, which is formed by laminating a positive electrode layer and a negative electrode layer with a solid electrolyte layer interposed therebetween, and comprises: a first solid electrolyte layer laminated with the aforementioned positive electrode layer; a third solid electrolyte layer arranged on the side of the aforementioned negative electrode layer; and a second solid electrolyte layer connecting the aforementioned first solid electrolyte layer and the aforementioned third solid electrolyte layer; and the particle size of the solid electrolyte particles constituting the aforementioned second solid electrolyte layer is smaller than the particle size of the solid electrolyte particles constituting the aforementioned first solid electrolyte layer and the aforementioned third solid electrolyte layer.

[0025] According to the invention of (7), an all-solid-state battery can be provided, which can improve battery performance by improving interface bonding properties.

[0026] (8) The all-solid-state battery according to any one of (1) to (7), wherein another layer is arranged between the negative electrode layer and the third solid electrolyte layer, and the third solid electrolyte layer is bonded to the other layer.

[0027] According to the invention of (8), the interface bonding properties can be further improved.

[0028] (9) A method for manufacturing an all-solid-state battery, wherein the all-solid-state battery is formed by laminating a positive electrode layer and a negative electrode layer with a solid electrolyte layer interposed therebetween, the method comprising the following steps: a first pressing step, wherein the layers comprising the positive electrode layer and the first solid electrolyte layer are pressed together to manufacture a first laminate; a second pressing step, wherein the layers comprising the negative electrode layer and the third solid electrolyte layer are pressed together 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 pressing step, wherein the first laminate and the second laminate are pressed together with the second solid electrolyte layer interposed therebetween; 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.

[0029] According to the invention of (9), an all-solid-state battery can be manufactured, which can improve battery performance by improving interface bonding properties.

[0030] (10) The method for manufacturing an all-solid-state battery according to (9), wherein the materials constituting the first solid electrolyte layer, the second solid electrolyte layer, and the third solid electrolyte layer are the same material.

[0031] According to the invention of (10), the interface bonding properties can be further improved.

[0032] (11) A method for manufacturing an all-solid-state battery according to (9) or (10), wherein the interface between the second solid electrolyte layer after the third pressing step and the first solid electrolyte layer and the third solid electrolyte layer extends into the first solid electrolyte layer side and the third solid electrolyte layer side.

[0033] According to the invention of (11), the interface bonding properties can be further improved.

[0034] (12) A method for manufacturing 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 aforementioned second solid electrolyte layer is less than 1 / 2 of the particle size D50 of the solid electrolyte particles constituting the aforementioned first solid electrolyte layer and the particle size D50 of the solid electrolyte particles constituting the aforementioned third solid electrolyte layer.

[0035] According to the invention of (12), the interface bonding properties can be further improved.

[0036] (13) A method for manufacturing an all-solid-state battery according to any one of (9) to (12), wherein the materials constituting the aforementioned first solid electrolyte layer, the aforementioned second solid electrolyte layer and the aforementioned third solid electrolyte layer are sulfide solid electrolytes, and at least one of polyvinylidene fluoride adhesives and styrene butadiene adhesives, the particle size D10 of the solid electrolyte particles constituting the aforementioned first solid electrolyte layer and the aforementioned third solid electrolyte layer is 0.4 μm, the particle size D50 is 0.7 μm, and the particle size D95 is 1.7 μm, and the particle size D50 of the solid electrolyte particles constituting the aforementioned second solid electrolyte layer is 0.2 μm.

[0037] According to the invention of (13), the interface bonding properties can be further improved.

[0038] (14) A method for manufacturing 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 the diameter of the substrate is smaller than the particle size of the solid electrolyte particles.

[0039] According to the invention of (14), the interface bonding properties can be further improved.

[0040] (15) A method for manufacturing an all-solid-state battery, wherein the all-solid-state battery is formed by laminating a positive electrode layer and a negative electrode layer with a solid electrolyte layer interposed therebetween, the method comprising the following steps: a first pressing step, wherein the layers comprising the positive electrode layer and the first solid electrolyte layer are pressed together to manufacture a first laminate; a step of arranging a third solid electrolyte layer on the side of the negative electrode 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 pressing step, wherein the first laminate and the second laminate are pressed together with the second solid electrolyte layer interposed therebetween; 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.

[0041] According to the invention of (15), an all-solid-state battery can be manufactured, which can improve battery performance by improving interface bonding properties.

[0042] (16) A method for manufacturing an all-solid-state battery according to any one of (9) to (15), wherein the method for manufacturing an all-solid-state battery includes a step of configuring other layers between the aforementioned negative electrode layer and the aforementioned third solid electrolyte layer, and the aforementioned third solid electrolyte layer is bonded to the aforementioned other layers.

[0043] According to the invention of (16), the interface bonding properties can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic cross-sectional view showing an all-solid-state battery according to one embodiment of the present invention.

[0045] Figure 2 This is a schematic cross-sectional view showing the interface of a solid electrolyte layer according to one embodiment of the present invention.

[0046] Figure 3 This is a schematic cross-sectional view showing the interface of a solid electrolyte layer according to another embodiment. DETAILED DESCRIPTION

[0047] [All-solid-state battery]

[0048] The all-solid-state battery 1 has a structure in which a positive electrode layer and a negative electrode layer are laminated with a solid electrolyte layer interposed therebetween. Figure 1 As shown, the all-solid-state battery 1 includes an electrode laminate formed by laminating, in sequence, a negative electrode layer 2, solid electrolyte layers 41, 42, 43, and a positive electrode layer 3. The structure of the all-solid-state battery 1 is not limited to the above; as long as the negative electrode layer 2 and the positive electrode layer 3 are laminated with three solid electrolyte layers 41, 42, 43 interposed therebetween, the number of layers is not particularly limited.

[0049] The solid electrolyte layer in the all-solid-state battery 1 includes a first solid electrolyte layer 41 disposed on the positive electrode layer 3 side, a third solid electrolyte layer 43 disposed on the negative electrode 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. Other layers such as an intermediate layer may be optionally laminated between the negative electrode layer 2 and the third solid electrolyte layer 43.

[0050] The all-solid-state battery 1 is not particularly limited and may be a lithium-ion solid-state secondary battery or a lithium metal secondary battery.

[0051] (Negative electrode layer)

[0052] The negative electrode layer 2 has a negative electrode active material layer 22 and a negative electrode collector layer 21. The negative electrode active material layer 22 is not particularly limited and can be composed of a material that can be used as a negative electrode active material for a solid-state battery. As the negative electrode active material layer 22, for example, a lithium metal layer can be listed. Among the above-mentioned lithium metals, in addition to lithium metal monomers, lithium alloys and the like can also be included. In addition to the above, the negative electrode active material layer 22 can also be composed of silicon-based active materials such as Si and Si alloys, lithium titanate (Li4Ti5O 12 ) and other lithium transition metal oxides, TiO2, Nb2O3 and WO3 and other transition metal oxides, metal sulfides, metal nitrides, graphite, soft carbon and hard carbon and other carbon materials, metal indium and the like.

[0053] In addition to the above, the negative electrode active material layer 22 may also include materials that can be contained in the negative electrode active material layer of a solid-state battery. Examples of the above materials include solid electrolytes, conductive additives, adhesives, and the like. Examples of solid electrolytes include solid electrolytes that are the same as those contained in the solid electrolyte layer described later. Examples of conductive additives include carbon black, natural graphite, carbon fibers, carbon nanotubes, and the like. Examples of adhesives include nitrile adhesives, polyester adhesives, acrylic adhesives, cellulose adhesives, styrene adhesives, styrene butadiene adhesives, vinyl acetate adhesives, polyurethane adhesives, vinyl fluoride adhesives, and polyvinylidene fluoride adhesives.

[0054] The negative electrode current collector layer 21 is not particularly limited and can 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 specific direction to form a negative electrode current collector tab.

[0055] (positive electrode layer)

[0056] The positive electrode layer 3 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 composed of a material that can be used as a positive electrode active material for a solid-state battery. Examples of positive electrode active materials constituting the positive electrode active material layer 31 include LiCoO2, LiNiO2, LiCo x Ni y Mn z O2(x+y+z=1), LiVO2, LiCrO2 and other layered positive electrode active material particles, LiMn2O4, Li(Ni 0.25 Mn 0.75 )2O4, LiCoMnO4, Li2NiMn3O8 and other spinel positive electrode active materials, LiCoPO4, LiMnPO4, LiFePO4 and other olivine positive electrode active materials, solid solution oxides (Li2MnO3-LiMO2 (M = Co, Ni, etc.)), aniline, polypyrrole and other conductive polymers, Li2S, CuS, Li-Cu-S compounds, TiS2, FeS, MoS2, Li-Mo-S compounds and other sulfides, mixtures of sulfur and carbon, etc. The above-mentioned positive electrode active material can use one of the above-mentioned materials, or can be a structure composed of two or more of the above-mentioned materials.

[0057] The positive electrode current collector layer is not particularly limited and can be made of, for example, aluminum, stainless steel, or conductive carbon (graphite, carbon nanotubes, etc.). Examples of the shape of the positive electrode current collector layer include foil, sheet, mesh, nonwoven fabric, and foam. A portion of the positive electrode current collector layer extends in a specific direction, forming the positive electrode current collector tab.

[0058] (Solid electrolyte layer)

[0059] Solid electrolyte layers 41, 42, and 43 are formed between the negative electrode layer 2 and the positive electrode layer 3. In this embodiment, a first solid electrolyte layer 41, a second solid electrolyte layer 42, and a third solid electrolyte layer 43 are stacked in this order. The first solid electrolyte layer 41 is pressed against the positive electrode layer 3, and the third solid electrolyte layer 43 is pressed against the negative electrode layer 2. The second solid electrolyte layer 42 joins the first solid electrolyte layer 41 and the third solid electrolyte layer 43.

[0060] The first solid electrolyte layer 41 is pressed against 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 (having only concavities and convexities corresponding to the particle size of the solid electrolyte particles).

[0061] The solid electrolyte material constituting the first solid electrolyte layer 41 is not particularly limited, as long as it is a material that can be used as an electrolyte for a solid-state battery. For example, sulfide solid electrolytes, oxide solid electrolytes, halide solid electrolytes, inorganic solid electrolytes such as lithium salts, or polymer solid electrolytes such as polyethylene oxide can be mentioned. Sulfide solid electrolytes are particularly preferred. The above solid electrolytes can be used alone or in combination of two or more.

[0062] The solid electrolyte material constituting the first solid electrolyte layer 41 is in a granular form. The solid electrolyte particles constituting the first solid electrolyte layer 41 preferably have a particle size D10 (median diameter) of 0.3 μm to 0.5 μm, a particle size D50 (median diameter) of 0.5 μm to 1.0 μm, and a particle size D95 (median diameter) of 1.5 μm to 2.0 μm.

[0063] In addition to the solid electrolyte material, the first solid electrolyte layer 41 may also include materials that can be used in solid electrolyte layers of solid-state batteries. For example, the first solid electrolyte layer 41 may also include a binder. Examples of the binder include nitrile binders, polyester binders, acrylic binders, cellulose binders, styrene binders, styrene-butadiene binders, vinyl acetate binders, polyurethane binders, vinyl fluoride binders, and polyvinylidene fluoride binders. In particular, it is preferred to include at least one of polyvinylidene fluoride binders and styrene-butadiene binders.

[0064] The third solid electrolyte layer 43 is disposed on the negative electrode layer 2 side. The third solid electrolyte layer 43 may also be press-bonded to the negative electrode layer 2. When an intermediate layer is provided between the negative electrode layer 2 and the third solid electrolyte layer 43, the third solid electrolyte layer 43 may also be press-bonded to the negative electrode layer 2 via the intermediate layer. The configuration of the third solid electrolyte layer 43 other than the above may be the same as that of the first solid electrolyte layer 41.

[0065] The intermediate layer is disposed between the negative electrode 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 precipitating the lithium metal. Therefore, the interface between the intermediate layer and the third solid electrolyte layer 43 is stable. When the all-solid-state battery 1 is a lithium metal secondary battery having an intermediate layer, the all-solid-state battery 1 can also be a negative electrode-free battery in which the negative electrode active material layer 22 is not present during the initial charge. In this case, after the initial charge and discharge, a lithium metal layer is formed as the negative electrode active material layer 22.

[0066] The material constituting the intermediate layer is not particularly limited, and examples thereof include metals that can form alloys with lithium, or amorphous carbon. Examples of metals that can form alloys with lithium include tin (Sn), silicon (Si), zinc (Zn), magnesium (Mg), gold (Au), platinum (Pt), palladium (Pd), silver (Ag), aluminum (Al), bismuth (Bi), antimony (Sb), and the like. Metals that can form alloys with lithium may also be nanoparticles. Examples of amorphous carbon include carbon blacks such as acetylene black, furnace black, and Ketjen black, coke, and activated carbon. Amorphous carbon may be easily graphitized carbon (soft carbon), or difficult to graphitize carbon (hard carbon), carbon nanotubes (CNTs), fullerenes, and graphene. In addition to the above substances, the intermediate layer may also include a binder.

[0067] Second solid electrolyte layer 42 joins first solid electrolyte layer 41 and third solid electrolyte layer 43. The particle size (e.g., median diameter D50) of the solid electrolyte particles constituting second solid electrolyte layer 42 is smaller than that of first and third solid electrolyte layers 41, 43. This allows the particles constituting second solid electrolyte layer 42 to enter the interface with first and third solid electrolyte layers 41, 43, resulting in improved bonding. This will be described below with reference to the accompanying drawings.

[0068] Figure 2 Schematic diagram showing the interface between the second solid electrolyte layer 42 and the third solid electrolyte layer 43. Figure 2 In the embodiment, 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. Figure 2 In the example, the particle size of the solid electrolyte particles 42a is less than or equal to 1 / 2 of the particle size of the solid electrolyte particles 43a.

[0069] In contrast, Figure 3 4 is a diagram showing an example in which the particle diameter of the solid electrolyte particles 42b constituting the second solid electrolyte layer 42 is substantially the same as that of the solid electrolyte particles 43a constituting the third solid electrolyte layer 43. Figure 2 and Figure 3 For comparison, Figure 3 In the embodiment, two solid electrolyte particles 42b are tangent to one solid electrolyte particle 43a at the tangent point P2. In contrast, Figure 2 In the example, two solid electrolyte particles 42a are tangent to one solid electrolyte particle 43a at the tangent point P1. That is, the particle size of the solid electrolyte particle 42a is set to be less than 1 / 2 of the particle size of the solid electrolyte particle 43a, so that the number of tangent points can be set to 1.5 times. Figure 3 Compared to the example in Figure 2In the example of , the interface bonding area S1 is larger than S2. This can improve the bonding between the second solid electrolyte layer 42 and the third solid electrolyte layer 43.

[0070] like Figure 2 As shown, the solid electrolyte particles 42a constituting the second solid electrolyte layer 42 enter the interface side of the third solid electrolyte layer 43. Specifically, Figure 3 Compared with the situation in Figure 2 In the structure of , the penetration amount G1 is about 40% greater than the penetration amount G2, and the length of the bonding interface line is increased by about 5%. Figure 2 and Figure 3 As shown, the above penetration amount refers to the difference (interval) between the average of the deepest position of each solid electrolyte particle 42a existing at the interface with the third solid electrolyte layer 43 and the average of the deepest position of each solid electrolyte particle 43a on the second solid electrolyte layer 42. The bonding interface line length is, for example, Figure 2 and Figure 3 The length of the cross section when observing the interface bonding area S1 and S2. Figure 2 The structure can improve the bonding property between the second solid electrolyte layer 42 and the third solid electrolyte layer 43.

[0071] In order to preferably obtain the above-mentioned effect of improving the bonding properties, the particle diameter D50 (median diameter) of the solid electrolyte particles constituting the second solid electrolyte layer 42 is preferably 0.2 μm to 0.3 μm.

[0072] Furthermore, the second solid electrolyte layer 42 may further include a substrate capable of being filled with a solid electrolyte. The substrate is not particularly limited, and an example thereof includes a nonwoven fabric. When the second solid electrolyte layer 42 includes a substrate, the diameter (fiber diameter) of the substrate is preferably smaller than the particle size of the solid electrolyte particles constituting the second solid electrolyte layer 42.

[0073] exist Figure 2 and Figure 3 , the interface between the second solid electrolyte layer 42 and the third solid electrolyte layer 43 is shown as an example, but the interface between the second solid electrolyte layer 42 and the first solid electrolyte layer 41 is also the same.

[0074] In this embodiment, the solid electrolyte material constituting the first solid electrolyte layer 41, the second solid electrolyte layer 42, and the third solid electrolyte layer 43 is the same. This further improves the bonding properties of the layers. Furthermore, the type and content of the binder, as well as the presence or absence of a base material, may vary.

[0075] [Method for manufacturing all-solid-state batteries]

[0076] The manufacturing method of the all-solid-state battery of this embodiment includes the following processes: a first pressing process, which presses the layers including the positive electrode layer 3 and the first solid electrolyte layer 41 to manufacture the first laminate L1; a process of arranging the third solid electrolyte layer 43 on the side of the negative electrode layer 2 to manufacture the second laminate L2; a process of arranging unpressurized solid electrolyte particles between the first solid electrolyte layer 41 and the third solid electrolyte layer 43 to form the second solid electrolyte layer 42; and a third pressing process, which presses the first laminate L1 and the second laminate L2 with the second solid electrolyte layer 42 between them.

[0077] The first press-bonding step is a step of press-bonding the layers including the positive electrode active material layer side of the positive electrode layer 3 and the first solid electrolyte layer 41. The pressurizing pressure in the first press-bonding step can be, for example, 600 MPa to 1200 MPa.

[0078] The step of placing the third solid electrolyte layer 43 on the negative electrode layer 2 side may be a second pressing step, that is, pressing the layers including the negative electrode layer 2 and the third solid electrolyte layer 43 together to produce the second laminate L2. Furthermore, other layers such as an intermediate layer may be placed between the negative electrode layer 2 and the third solid electrolyte layer 43. The pressure applied in the second pressing step may be, for example, 300 MPa to 800 MPa.

[0079] The second solid electrolyte layer 42 is formed by placing unpressurized solid electrolyte particles between the first solid electrolyte layer 41 of the first laminate L1 and the third solid electrolyte layer 43 of the second laminate L2. Alternatively, 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 added.

[0080] In the process of forming the second solid electrolyte layer 42, the disposed solid electrolyte particles are not pressurized, so that the surface can have irregularities larger than the particle size of the solid electrolyte particles. Furthermore, since no pressure is applied, the Young's modulus is low.

[0081] The first laminate L1 and the second laminate L2 are bonded together in the third pressing step. The pressing pressure in the third pressing step can be, for example, 300 MPa to 800 MPa.

[0082] As described above, since the particle size of the solid electrolyte particles constituting the second solid electrolyte layer 42 is smaller than that of the solid electrolyte particles constituting the first solid electrolyte layer 41 or the third solid electrolyte layer 43, they can enter the interface, thereby improving interfacial bonding. Furthermore, even if the pressure applied in the third press-bonding step is reduced, the density of the second solid electrolyte layer 42 can be increased, that is, the resistance can be reduced.

[0083] The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments. Figure 1 In addition to the laminated structure shown, the all-solid-state battery 1 may have a structure that can be used for a solid-state battery, such as an outer package.

[0084] Reference numerals

[0085] 1. All-solid-state battery (laminated structure of all-solid-state battery)

[0086] 2 negative electrode layer

[0087] 3 positive electrode layer

[0088] 41First solid electrolyte layer

[0089] 42 Second solid electrolyte layer

[0090] 43 Third solid electrolyte layer

[0091] L1 first laminate

[0092] L2 Second laminate

Claims

1. An all-solid-state battery, which is composed of a positive electrode layer and a negative electrode layer laminated with a solid electrolyte layer, having: A first solid electrolyte layer, pressed together with the aforementioned positive electrode layer; A third solid electrolyte layer is laminated with the aforementioned negative electrode layer; and a second solid electrolyte layer connecting the first solid electrolyte layer and the third solid electrolyte layer; 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.

2. The all-solid-state battery according to claim 1, wherein: The materials constituting the first solid electrolyte layer, the second solid electrolyte layer, and the third solid electrolyte layer are the same material.

3. The all-solid-state battery according to claim 1, wherein: The interface between the second solid electrolyte layer and the first and third solid electrolyte layers extends into the first and third solid electrolyte layers.

4. The all-solid-state battery according to claim 1, wherein: The particle size D50 of the solid electrolyte particles constituting the second solid electrolyte layer is less than 1 / 2 of 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.

5. The all-solid-state battery according to claim 4, wherein: The materials constituting the first solid electrolyte layer, the second solid electrolyte layer, and the third solid electrolyte layer are at least one of a sulfide solid electrolyte, a polyvinylidene fluoride binder, and a styrene butadiene binder. The solid electrolyte particles constituting the first solid electrolyte layer and the third solid electrolyte layer have a particle size D10 of 0.3 to 0.5 μm, a particle size D50 of 0.5 to 1.0 μm, and a particle size D95 of 1.5 to 2.0 μm. The particle size D50 of the solid electrolyte particles constituting the second solid electrolyte layer is 0.2 to 0.3 μm.

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

7. An all-solid-state battery, comprising a positive electrode layer and a negative electrode layer laminated with a solid electrolyte layer interposed therebetween, having: A first solid electrolyte layer, pressed together with the aforementioned positive electrode layer; A third solid electrolyte layer is disposed on the negative electrode layer side; and a second solid electrolyte layer connecting the first solid electrolyte layer and the third solid electrolyte layer; 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.

8. The all-solid-state battery according to any one of claims 1 to 7, wherein Another layer is arranged between the negative electrode layer and the third solid electrolyte layer. The third solid electrolyte layer is bonded to the other layers.

9. A method for manufacturing an all-solid-state battery, wherein the all-solid-state battery is formed by laminating a positive electrode layer and a negative electrode layer with a solid electrolyte layer interposed therebetween, the method comprising the following steps: a first lamination step of laminating the layers including the positive electrode layer and the first solid electrolyte layer to produce a first laminate; a second lamination step of laminating the layers including the negative electrode layer and the third solid electrolyte layer to produce a second laminate; a step of disposing 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 pressing step of pressing the first laminate and the second laminate together via the second solid electrolyte layer; 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.

10. The method for manufacturing an all-solid-state battery according to claim 9, wherein: The materials constituting the first solid electrolyte layer, the second solid electrolyte layer, and the third solid electrolyte layer are the same material.

11. The method for manufacturing an all-solid-state battery according to claim 9, wherein: The interface between the second solid electrolyte layer after the third pressing step and the first solid electrolyte layer and the third solid electrolyte layer extends into the first solid electrolyte layer side and the third solid electrolyte layer side.

12. The method for manufacturing an all-solid-state battery according to claim 9, wherein: The particle size D50 of the solid electrolyte particles constituting the second solid electrolyte layer is less than 1 / 2 of 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.

13. The method for manufacturing an all-solid-state battery according to claim 12, wherein: The materials constituting the first solid electrolyte layer, the second solid electrolyte layer, and the third solid electrolyte layer are at least one of a sulfide solid electrolyte, a polyvinylidene fluoride binder, and a styrene butadiene 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. The particle size D50 of the solid electrolyte particles constituting the second solid electrolyte layer was 0.2 μm.

14. The method for manufacturing an all-solid-state battery according to claim 9, wherein: The second solid electrolyte layer includes solid electrolyte particles and a substrate. The diameter of the substrate is smaller than the particle size of the solid electrolyte particles.

15. A method for manufacturing an all-solid-state battery, wherein the all-solid-state battery is formed by laminating a positive electrode layer and a negative electrode layer with a solid electrolyte layer interposed therebetween, the method comprising the following steps: a first lamination step of laminating the layers including the positive electrode layer and the first solid electrolyte layer to produce a first laminate; a step of disposing a third solid electrolyte layer on the negative electrode layer side to produce a second laminate; a step of disposing 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 pressing step of pressing the first laminate and the second laminate together via the second solid electrolyte layer; 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.

16. The method for manufacturing an all-solid-state battery according to any one of claims 9 to 15, wherein: The method for manufacturing the all-solid-state battery includes the 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 other layer.

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