All-solid-state battery and manufacturing method thereof

Abstract

To provide an all-solid-state battery having a solid electrolyte layer with a high ion conductivity, and a manufacturing method thereof.SOLUTION: An all-solid-state battery comprises a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer. The solid electrolyte layer is a laminate having a first solid electrolyte layer and a second solid electrolyte layer laminated on one surface of the base material-containing solid electrolyte layer, where the first solid electrolyte layer includes a porous base material and a first solid electrolyte composition containing a solid electrolyte filled in pores of the porous base material, and the second solid electrolyte layer includes a second solid electrolyte composition containing a solid electrolyte and does not include a base material.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In recent years, research and development has been conducted on secondary batteries that contribute to energy efficiency, ensuring that more people have access to affordable, reliable, sustainable, and advanced energy. Among secondary batteries, all-solid-state batteries, which have a laminated structure in which a solid electrolyte layer is disposed between a positive electrode layer and a negative electrode layer and then compressed, have attracted particular attention due to their superior safety as the solid electrolyte is non-flammable and their higher energy density. Known solid electrolyte layers for all-solid-state batteries are formed by filling the pores of a porous substrate with a solid electrolyte (Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-153460 [Patent Document 2] Japanese Patent Publication No. 2021-163759 Summary of the Invention [Problem to be solved by the invention]

[0004] One of the challenges facing all-solid-state batteries is improving their high-rate performance. To improve the high-rate performance of all-solid-state batteries, it is effective to improve the ionic conductivity of the solid electrolyte layer. However, in a solid electrolyte layer in which a solid electrolyte is filled into the pores of a porous substrate, pinholes may form between the pores of the porous substrate and the solid electrolyte, resulting in a decrease in ionic conductivity.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an all-solid-state battery having a solid electrolyte layer with high ionic conductivity and a method for manufacturing the same. [Means for solving the problem]

[0006] The present inventors have found that the above-mentioned problems can be solved by forming a solid electrolyte layer by compressing a second solid electrolyte layer containing a second solid electrolyte composition but not a substrate onto one surface of a first solid electrolyte layer having a porous substrate with a first solid electrolyte composition filled in the pores thereof, and have thus completed the present invention.

[0007] (1) An all-solid-state battery comprising a pressure-bonded laminate in which a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer are pressure-bonded to one surface of the first solid electrolyte layer, the solid electrolyte layer having a first solid electrolyte layer and a second solid electrolyte layer pressure-bonded to one surface of the first solid electrolyte layer, the first solid electrolyte layer being a substrate-containing body including a porous substrate and a first solid electrolyte composition containing a solid electrolyte filled in pores of the porous substrate, and the second solid electrolyte layer including a second solid electrolyte composition containing a solid electrolyte, and being a substrate-free body not including a substrate.

[0008] According to the all-solid-state battery (1), the first solid electrolyte layer and the second solid electrolyte layer of the pressure-bonded laminate are pressure-bonded together, so that pinholes formed in the first solid electrolyte layer are filled with the second solid electrolyte composition of the second solid electrolyte layer, and therefore, the all-solid-state battery including this pressure-bonded laminate has high ionic conductivity in the solid electrolyte layer and improved high-rate characteristics.

[0009] (2) The all-solid-state battery according to (1), wherein the first solid electrolyte layer is pressure-bonded to the positive electrode layer, and the second solid electrolyte layer is pressure-bonded to the negative electrode layer.

[0010] In the all-solid-state battery (2), the first solid electrolyte layer including the porous substrate is pressure-bonded to the positive electrode layer, allowing the positive electrode layer to be made of a material with high strength, while the second solid electrolyte layer not including the porous substrate is pressure-bonded to the negative electrode layer, allowing the negative electrode layer to be made of a material with low strength.

[0011] (3) The all-solid-state battery according to (1) or (2), wherein the outer peripheral edge of the first solid electrolyte layer is larger than the outer peripheral edge of at least one of the positive electrode layer and the negative electrode layer in a plan view.

[0012] In the all-solid-state battery (3), the outer peripheral edge of the first solid electrolyte layer is larger than the outer peripheral edge of at least one of the positive electrode layer and the negative electrode layer in a plan view, so that the positive electrode layer and the negative electrode layer are less likely to short-circuit.

[0013] (4) The all-solid-state battery according to any one of (1) to (3), wherein the first solid electrolyte composition and the second solid electrolyte composition each contain a binder, and the binder content of the first solid electrolyte composition is higher than the binder content of the second solid electrolyte composition.

[0014] In the all-solid-state battery (4), the first solid electrolyte composition has a high binder content, which enhances adhesion to the porous substrate and reduces the likelihood of pinholes forming in the first solid electrolyte layer, while the second solid electrolyte composition has a low binder content, which enhances the ionic conductivity of the second solid electrolyte layer.

[0015] (5) The all-solid-state battery according to any one of (1) to (4), wherein the positive electrode layer includes a sheet-shaped positive electrode current collector and two positive electrode active material layers stacked on both surfaces of the positive electrode current collector, and the negative electrode layers are disposed so as to sandwich the positive electrode layer.

[0016] In the all-solid-state battery (5), a solid electrolyte layer is disposed on the surfaces of two positive electrode active material layers, thereby forming a sealed structure in which the positive electrode layer is surrounded by the solid electrolyte layer. This prevents the negative electrode tab connected to the negative electrode layer from wrapping around the positive electrode layer, thereby preventing a short circuit between the positive electrode layer and the negative electrode layer.

[0017] (6) A method for producing an all-solid-state battery, comprising: a laminate including a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer; the solid electrolyte layer having a first solid electrolyte layer and a second solid electrolyte layer disposed on one surface of the first solid electrolyte layer; the first solid electrolyte layer being a substrate-containing body including a porous substrate and a first solid electrolyte composition containing a solid electrolyte filled in pores of the porous substrate; and the second solid electrolyte layer including a second solid electrolyte composition containing a solid electrolyte; the method comprising: a step of pressurizing a laminate that is a substrate-free body not including a substrate to pressure-bond each layer.

[0018] According to the method for producing an all-solid-state battery in (6), the first solid electrolyte layer and the second solid electrolyte layer are pressure-bonded together, so that pinholes formed in the first solid electrolyte layer can be filled with the second solid electrolyte composition of the second solid electrolyte layer, and therefore the resulting all-solid-state battery has high ionic conductivity in the solid electrolyte layer and improved high-rate performance.

[0019] (7) The method for producing an all-solid-state battery according to (6), wherein the first solid electrolyte layer of the laminate is laminated on the positive electrode layer, and the second solid electrolyte layer is laminated on the negative electrode layer.

[0020] According to the method for manufacturing an all-solid-state battery (7), since the first solid electrolyte layer including the porous substrate is pressure-bonded to the positive electrode layer, a material with high strength can be used for the positive electrode layer, and since the second solid electrolyte layer not including the porous substrate is pressure-bonded to the negative electrode layer, a material with low strength can be used for the negative electrode layer.

[0021] (8) The method for producing an all-solid-state battery according to (7), wherein the positive electrode layer and the first solid electrolyte layer of the laminate are pressure-bonded.

[0022] According to the method for producing an all-solid-state battery in (8), the positive electrode layer and the first solid electrolyte layer are preliminarily pressure-bonded together, and therefore, the obtained all-solid-state battery has high adhesion between the positive electrode layer and the first solid electrolyte layer, and the ionic conductivity between the positive electrode layer and the solid electrolyte layer is improved.

[0023] (9) The method for producing an all-solid-state battery according to (7) or (8), wherein the negative electrode layer of the laminate and the second solid electrolyte layer are pressure-bonded to each other.

[0024] According to the method for producing an all-solid-state battery in (9), the anode layer and the second solid electrolyte layer are preliminarily pressure-bonded together, so that the resulting all-solid-state battery has high adhesion between the anode layer and the second solid electrolyte layer, and the ionic conductivity between the anode layer and the solid electrolyte layer is improved. [Effects of the Invention]

[0025] According to the present invention, it is possible to provide an all-solid-state battery having a solid electrolyte layer with high ionic conductivity and a method for manufacturing the same. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a plan view showing a pressure-bonded laminate of an all-solid-state battery according to an embodiment of the present invention. [Figure 2] FIG. 3 is a cross-sectional view taken along line II-II in FIG. 2. [Figure 3] FIG. 2 is a cross-sectional view illustrating a method for manufacturing an all-solid-state battery according to one embodiment of the present invention, showing a positive electrode layer-first solid electrolyte layer pressure-bonded laminate. [Figure 4] FIG. 2 is a cross-sectional view showing a negative electrode layer-second solid electrolyte layer pressure-bonded laminate obtained by a method for producing an all-solid-state battery according to one embodiment of the present invention. [Figure 5] FIG. 2 is a cross-sectional view illustrating a step of pressing a laminate, which is one step of a method for manufacturing an all-solid-state battery according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiments described below are merely examples of the present invention, and the present invention is not limited to the following.

[0028] Fig. 1 is a plan view showing a pressure-bonded laminate of an all-solid-state battery according to one embodiment of the present invention, Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. As shown in FIGS. 1 and 2, the pressure-bonded laminate 10 is a laminate in which a positive electrode layer 20, a negative electrode layer 30, and a solid electrolyte layer disposed between the positive electrode layer 20 and the negative electrode layer 30 are pressure-bonded together.

[0029] The positive electrode layer 20 includes a positive electrode current collector 21 and two positive electrode active material layers 22 laminated on both surfaces of the positive electrode current collector 21. The positive electrode current collector 21 is connected to a positive electrode tab 25. The negative electrode layers 30 are disposed opposite each other with the positive electrode layer 20 interposed therebetween. Each of the two opposing negative electrode layers 30 includes a negative electrode current collector 31 and a metal layer 32 laminated on the surface of the negative electrode current collector 31 facing the solid electrolyte layer 40. The negative electrode current collector 31 is connected to a negative electrode tab 35. The solid electrolyte layer 40 is disposed between the positive electrode active material layer 22 and the negative electrode current collector 31. The solid electrolyte layer 40 includes a first solid electrolyte layer 41 and a second solid electrolyte layer 42 pressed onto one surface of the first solid electrolyte layer 41. The first solid electrolyte layer 41 is pressed onto the positive electrode layer 20, and the second solid electrolyte layer 42 is pressed onto the negative electrode layer 30. The outer peripheral edge of the first solid electrolyte layer 41 is larger in size than the outer peripheral edge of the positive electrode layer 20 in plan view.

[0030] The first solid electrolyte layer 41 is a substrate-containing body including a porous substrate and a first solid electrolyte composition filling the pores of the porous substrate. The second solid electrolyte layer 42 is a substrate-free body including a second solid electrolyte composition containing a solid electrolyte, and does not include a substrate. By pressing the first solid electrolyte layer 41 and the second solid electrolyte layer 42 together and pressing the second solid electrolyte layer 42 against pinholes formed in the first solid electrolyte layer 41, the pinholes can be filled with the second solid electrolyte composition.

[0031] There are no particular limitations on the material or shape of the positive electrode current collector 21, as long as it has the function of collecting current from the positive electrode layer 20. Examples of materials for the positive electrode current collector 21 include aluminum, aluminum alloys, stainless steel, nickel, iron, and titanium, and among these, aluminum, aluminum alloys, and stainless steel are preferred. Examples of the shape of the positive electrode current collector 21 include a foil shape and a plate shape.

[0032] The positive electrode active material layer 22 contains at least one type of positive electrode active material. There are no particular limitations on the positive electrode active material, and any material that is used in the positive electrode layer of a general all-solid-state battery can be used. As the positive electrode active material, for example, a layered active material containing lithium, a spinel-type active material, an olivine-type active material, etc. can be used. Specific examples of the positive electrode active material include lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), LiNi p Mn q Co r O2(p+q+r=1), LiNi p Al q Co r O2 (p+q+r=1), lithium manganese oxide (LiMn2O4), Li 1+x Mn 2-x-y Examples include heteroelement-substituted Li-Mn spinel represented by MO4 (x+y=2, M=at least one selected from Al, Mg, Co, Fe, Ni, and Zn), lithium titanate (oxide containing Li and Ti), and lithium metal phosphate (LiMPO4, M=at least one selected from Fe, Mn, Co, and Ni).

[0033] The positive electrode active material layer 22 may optionally contain a solid electrolyte from the viewpoint of improving lithium ion conductivity. It may also optionally contain a conductive additive to improve conductivity. Furthermore, it may also optionally contain a binder from the viewpoint of exhibiting flexibility, etc. There are no particular restrictions on the solid electrolyte, conductive additive, and binder, and those used in the positive electrode layer of a general all-solid-state battery may be used.

[0034] The material of the positive electrode tab 25 may be the same as or different from the material of the positive electrode current collector 21. The positive electrode tab 25 may be integrally connected to the positive electrode current collector 21. In this embodiment, the positive electrode tab 25 is formed by extending the positive electrode current collector 21, and is integrally connected to the positive electrode current collector 21.

[0035] The material and shape of the negative electrode current collector 31 are not particularly limited as long as it has the function of collecting current from the negative electrode layer 30. Examples of materials for the negative electrode current collector 31 include nickel, copper, and stainless steel. Examples of the shape of the negative electrode current collector 31 include a foil shape, a plate shape, and the like.

[0036] The metal layer 32 is not particularly limited in material or shape as long as it has the function of densely depositing lithium ions. A metallic lithium layer or a layer of a metal that forms an alloy with lithium can be used as the metal layer 32. Examples of metals that form an alloy with lithium include Mg, Si, Au, Ag, In, Ge, Sn, Pb, Al, and Zn. The metal that forms the metal layer 32 may be in the form of a powder or a thin film. By using the anode layer 30 having this metal layer 32, a uniform lithium deposit layer can be formed on the surface of the metal layer 32.

[0037] The material of the negative electrode tab 35 may be the same as or different from the material of the negative electrode current collector 31. The negative electrode tab 35 may be integrally connected to the negative electrode current collector 31. In this embodiment, the negative electrode tab 35 is formed by extending the negative electrode current collector 31, and is integrally connected to the negative electrode current collector 31.

[0038] The thickness of the first solid electrolyte layer 41 of the solid electrolyte layer 40 may be the same as or different from the thickness of the second solid electrolyte layer 42. The thickness of the second solid electrolyte layer 42 may be thicker than the thickness of the first solid electrolyte layer 41, for example.

[0039] The porous substrate included in first solid electrolyte layer 41 may be, for example, a nonwoven fabric or a woven fabric.

[0040] The first solid electrolyte composition of the first solid electrolyte layer 41 and the second solid electrolyte composition of the second solid electrolyte layer 42 may contain a solid electrolyte and a binder. The solid electrolytes of the first solid electrolyte composition and the second solid electrolyte composition may be the same or different. The first solid electrolyte composition may contain two or more solid electrolytes with different average particle sizes. For example, the first solid electrolyte composition may contain a fine solid electrolyte having an average particle size of 0.1 μm or more and less than 0.5 μm and a coarse solid electrolyte having an average particle size of 1.0 μm or more and 10.0 μm or less. The ratio of the fine solid electrolyte to the coarse solid electrolyte may be in the range of 1:9 to 9:1 by mass. The fine solid electrolyte has the effect of improving the bonding between the first solid electrolyte layer 41 and the positive electrode layer 20. The coarse solid electrolyte has the effect of improving the filling property of the solid electrolyte composition in the first solid electrolyte layer 41. The average particle size of the solid electrolyte of the second solid electrolyte composition may be, for example, in the range of 1.0 μm or more and 10.0 μm or less. The average particle size of the solid electrolyte in the first solid electrolyte composition may be smaller than the average particle size of the solid electrolyte in the second solid electrolyte composition, where the average particle size is a value measured by a laser diffraction scattering method.

[0041] The solid electrolytes of the first solid electrolyte composition and the second solid electrolyte composition are not particularly limited as long as they have lithium ion conductivity, and examples thereof include sulfide solid electrolytes, oxide solid electrolytes, nitride solid electrolytes, and halide solid electrolytes.

[0042] Examples of sulfide solid electrolytes include Li2S-P2S5, Li2S-P2S5-LiI, etc. The sulfide solid electrolyte may have an argyrodite-type crystal structure.

[0043] Examples of oxide solid electrolytes include NASICON-type oxides, garnet-type oxides, and perovskite-type oxides. Examples of NASICON-type oxides include oxides containing Li, Al, Ti, P, and O (e.g., Li 1.5 Al 0.5 Ti 1.5Examples of garnet-type oxides include oxides containing Li, La, Zr, and O (e.g., LiLaZrO 12 Examples of perovskite oxides include oxides containing Li, La, Ti, and O (for example, LiLaTiO3).

[0044] The binders of the first solid electrolyte composition and the second solid electrolyte composition may be the same or different. There are no particular limitations on the type of binder, and binders used in solid electrolyte layers of general all-solid-state batteries can be used. The binder content of the first solid electrolyte composition can be set, for example, in consideration of the adhesion between the first solid electrolyte composition and the porous substrate, and the overall strength and ionic conductivity of the first solid electrolyte layer 41. The binder content of the second solid electrolyte composition can be set, for example, in consideration of the adhesion to the first solid electrolyte layer 41 and the overall ionic conductivity of the second solid electrolyte layer 42. The binder content of the first solid electrolyte composition may be higher than the binder content of the second solid electrolyte composition. The binder content of the first solid electrolyte composition may be, for example, in the range of 1.5 to 10 times the binder content of the second solid electrolyte composition.

[0045] The pressure-bonded laminate 10 is housed in an exterior body (not shown). The exterior body is provided with a positive electrode terminal connected to the positive electrode tab 25 and a negative electrode terminal connected to the negative electrode tab 35.

[0046] A laminate film can be used as the material for the exterior body. The laminate film can be a three-layer laminate film having an inner resin layer, a metal layer, and an outer resin layer laminated in this order from the inside. The outer resin layer can be, for example, a polyamide (nylon) layer or a polyethylene terephthalate (PET) layer, the metal layer can be, for example, an aluminum layer, and the inner resin layer can be, for example, a polyethylene layer or a polypropylene layer.

[0047] In the bonded laminate 10 of the present embodiment configured as described above, the first solid electrolyte layer 41 and the second solid electrolyte layer 42 of the solid electrolyte layer 40 are bonded together by pressure, so that pinholes formed in the first solid electrolyte layer 41 are filled with the second solid electrolyte composition of the second solid electrolyte layer 42. Therefore, in an all-solid-state battery including the bonded laminate 10, the ionic conductivity of the solid electrolyte layer 40 is high, and the high-rate characteristics are improved.

[0048] In the bonded laminate 10 of this embodiment, since the first solid electrolyte layer 41 is bonded to the positive electrode layer 20, a high-strength material can be used for the positive electrode active material layer 22. Furthermore, since the second solid electrolyte layer 42 is bonded to the negative electrode layer 30, a low-strength material can be used for the metal layer 32.

[0049] In the bonded laminate 10 of this embodiment, the outer peripheral edge of the first solid electrolyte layer 41 is larger than the outer peripheral edge of the positive electrode layer 20 in a plan view, making it difficult for the positive electrode layer 20 and the negative electrode layer 30 to short-circuit. In addition, by disposing the solid electrolyte layer 40 on the surfaces of the two positive electrode active material layers 22, a sealed structure is formed in which the positive electrode layer 20 is surrounded by the solid electrolyte layer 40, and this makes it possible to prevent the negative electrode tab 35 from wrapping around the positive electrode layer 20 and causing a short-circuit between the positive electrode layer 20 and the negative electrode layer 30.

[0050] In the bonded laminate 10 of this embodiment, the first solid electrolyte composition has a high binder content, which increases adhesion to the porous substrate and reduces the likelihood of pinholes occurring in the first solid electrolyte layer 41. The second solid electrolyte composition has a low binder content, which increases the ionic conductivity of the second solid electrolyte layer 42.

[0051] A method for producing the pressure-bonded laminate 10 of this embodiment will be described with reference to FIGS. Fig. 3 is a cross-sectional view illustrating a positive electrode layer-first solid electrolyte layer pressure-bonded laminate for explaining a method for producing an all-solid-state battery according to one embodiment of the present invention, Fig. 4 is a cross-sectional view illustrating a negative electrode layer-second solid electrolyte layer pressure-bonded laminate obtained by the method for producing an all-solid-state battery according to one embodiment of the present invention, Fig. 5 is a cross-sectional view illustrating a step of pressure-bonding a laminate, which is one step in the method for producing an all-solid-state battery according to one embodiment of the present invention.

[0052] In the method for manufacturing the pressure-bonded laminate 10 of this embodiment, first, as shown in Fig. 3, a positive electrode layer-first solid electrolyte layer pressure-bonded laminate 11 is obtained by pressure-bonding a positive electrode layer 20 and a first solid electrolyte layer 41. The positive electrode layer-first solid electrolyte layer pressure-bonded laminate 11 can be manufactured by overlapping the positive electrode active material layer 22 of the positive electrode layer 20 and the first solid electrolyte layer 41 and applying pressure. A roll press can be used as the pressure device.

[0053] 4, the metal layer 32 of the anode layer 30 and the second solid electrolyte layer 42 are pressure-bonded to obtain the anode layer-second solid electrolyte layer pressure-bonded laminate 12. The anode layer-second solid electrolyte layer pressure-bonded laminate 12 can be manufactured by overlapping the metal layer 32 of the anode layer 30 and the second solid electrolyte layer 42 and applying pressure. A roll press can be used as the pressure device. The pressure applied may be lower than the pressure used in manufacturing the cathode layer-first solid electrolyte layer pressure-bonded laminate 11.

[0054] Next, as shown in FIG. 5 , the first solid electrolyte layer 41 of the positive electrode layer-first solid electrolyte layer-compressed laminate 11 and the second solid electrolyte layer 42 of the negative electrode layer-second solid electrolyte layer-compressed laminate 12 are superposed to obtain a laminate including the positive electrode layer 20, the negative electrode layer 30, and the first solid electrolyte layer 41 and the second solid electrolyte layer 42 disposed between the positive electrode layer 20 and the negative electrode layer 30. Then, the laminate is pressurized to compress the first solid electrolyte layer 41 and the second solid electrolyte layer 42. The pressing pressure may be lower than the pressure used in manufacturing the positive electrode layer-first solid electrolyte layer-compressed laminate 11. The pressing pressure may also be higher than the pressure used in manufacturing the metal layer 32 and the second solid electrolyte layer 42.

[0055] An all-solid-state battery can be manufactured, for example, as follows: The positive electrode tab 25 of the obtained pressure-bonded laminate 10 is connected to a positive electrode terminal, and the negative electrode tab 35 is connected to a negative electrode terminal. Next, the pressure-bonded laminate 10 is housed in an exterior body so that the ends of the positive electrode terminal and the negative electrode terminal protrude, and the exterior body is sealed.

[0056] According to the above-described method for manufacturing the pressure-bonded laminate 10 of the present embodiment, the first solid electrolyte layer 41 and the second solid electrolyte layer 42 are pressure-bonded together, so that pinholes formed in the first solid electrolyte layer 41 can be filled with the second solid electrolyte composition of the second solid electrolyte layer 42. Therefore, an all-solid-state battery using the obtained pressure-bonded laminate 10 has high ionic conductivity in the solid electrolyte layer 40 and improved high-rate characteristics.

[0057] In the method for manufacturing the pressure-bonded laminate 10 of this embodiment, the first solid electrolyte layer 41 is pressure-bonded to the positive electrode layer 20, so a high-strength material can be used for the positive electrode active material layer 22. In addition, the second solid electrolyte layer 42 is pressure-bonded to the negative electrode layer 30, so a low-strength material can be used for the metal layer 32.

[0058] The method for manufacturing the pressure-bonded laminate 10 of this embodiment uses a cathode layer-first solid electrolyte layer pressure-bonded laminate 11 in which the cathode layer 20 and the first solid electrolyte layer 41 are pressure-bonded together in advance, so the resulting pressure-bonded laminate 10 has high adhesion between the cathode layer 20 and the first solid electrolyte layer 41, and therefore improves ionic conductivity between the cathode layer 20 and the solid electrolyte layer 40. Furthermore, the method uses an anode layer-second solid electrolyte layer pressure-bonded laminate 12 in which the anode layer 30 and the second solid electrolyte layer 42 are pressure-bonded together in advance, so the resulting pressure-bonded laminate 10 has high adhesion between the anode layer 30 and the second solid electrolyte layer 42, and therefore improves ionic conductivity between the anode layer 30 and the solid electrolyte layer 40.

[0059] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, in this embodiment, the positive electrode layer 20 has the positive electrode active material layer 22 laminated on both sides of the positive electrode current collector 21, but the positive electrode active material layer 22 may be laminated on only one side of the positive electrode current collector 21.

[0060] In addition, in this embodiment, the first solid electrolyte layer 41 is pressure-bonded to the positive electrode layer 20, and the second solid electrolyte layer 42 is pressure-bonded to the negative electrode layer 30, but the second solid electrolyte layer 42 may be pressure-bonded to the positive electrode layer 20, and the first solid electrolyte layer 41 may be pressure-bonded to the negative electrode layer 30.

[0061] Although the negative electrode layer 30 includes the metal layer 32 in this embodiment, the metal layer 32 may be omitted, and lithium may be deposited on the surface of the negative electrode current collector 31. Alternatively, the metal layer 32 may be replaced with a layer containing a negative electrode active material capable of absorbing and releasing lithium ions. Examples of the negative electrode active material include lithium transition metal oxides such as lithium titanate, transition metal oxides such as TiO2, Nb2O3, and WOn, Si, SiO2, metal sulfides, metal nitrides, and carbon materials such as artificial graphite, natural graphite, graphite, soft carbon, and hard carbon. The negative electrode active material layer may optionally contain a solid electrolyte to improve lithium ion conductivity. It may also optionally contain a conductive additive to improve conductivity. It may also optionally contain a binder to provide flexibility. The solid electrolyte, conductive additive, and binder may be those commonly used in solid-state secondary batteries.

[0062] Furthermore, in the method for manufacturing the pressure-bonded laminate 10 of this embodiment, the first solid electrolyte layer 41 of the positive electrode layer-first solid electrolyte layer pressure-bonded laminate 11 and the second solid electrolyte layer 42 of the negative electrode layer-second solid electrolyte layer pressure-bonded laminate 12 are pressure-bonded, but the method is not limited to this. For example, a laminate obtained by laminating the positive electrode layer 20, the first solid electrolyte layer 41, the second solid electrolyte layer 42, and the negative electrode layer 30 may be pressurized to pressure-bond the layers. Alternatively, a laminate obtained by pressure-bonding the first solid electrolyte layer 41 and the second solid electrolyte layer 42 may be placed between the positive electrode layer 20 and the negative electrode layer 30, and pressure may be applied to the resulting solid electrolyte layer 40 to pressure-bond the layers. [Explanation of symbols]

[0063] 10. Compression laminate 11 Positive electrode layer-first solid electrolyte layer pressure-bonded laminate 12 Negative electrode layer-second solid electrolyte layer pressure-bonded laminate 20 Positive electrode layer 21 Positive electrode current collector 22 Cathode active material layer 25 Positive electrode tab 30 negative electrode layer 31 Negative electrode current collector 32 metal layer 35 Negative electrode tab 40 Solid electrolyte layer 41 First solid electrolyte layer 42 Second solid electrolyte layer

Claims

1. a compressed laminate in which a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer are compressed together; the solid electrolyte layer includes a first solid electrolyte layer and a second solid electrolyte layer pressed onto one surface of the first solid electrolyte layer, The first solid electrolyte layer is a substrate-containing body including a porous substrate and a first solid electrolyte composition containing a solid electrolyte filled in pores of the porous substrate, the second solid electrolyte layer comprises a second solid electrolyte composition containing a solid electrolyte, and is a substrate-free body that does not contain a substrate.

2. 2. The all-solid-state battery according to claim 1, wherein the first solid electrolyte layer is pressed onto the positive electrode layer, and the second solid electrolyte layer is pressed onto the negative electrode layer.

3. 3 . The all-solid-state battery according to claim 1 , wherein an outer peripheral edge of the first solid electrolyte layer is larger than an outer peripheral edge of at least one of the positive electrode layer and the negative electrode layer in a plan view.

4. 3. The all-solid-state battery according to claim 1, wherein the first solid electrolyte composition and the second solid electrolyte composition each contain a binder, and the binder content of the first solid electrolyte composition is higher than the binder content of the second solid electrolyte composition.

5. 3. The all-solid-state battery according to claim 1, wherein the positive electrode layer includes a sheet-shaped positive electrode current collector and two positive electrode active material layers stacked on both surfaces of the positive electrode current collector, and the negative electrode layers are disposed so as to sandwich the positive electrode layer.

6. a first solid electrolyte layer and a second solid electrolyte layer disposed on one surface of the first solid electrolyte layer; the first solid electrolyte layer is a substrate-containing body including a porous substrate and a first solid electrolyte composition containing a solid electrolyte filled in pores of the porous substrate; and the second solid electrolyte layer includes a second solid electrolyte composition containing a solid electrolyte; and a substrate-free body including no substrate is applied to the laminate to compress and bond the layers together.

7. 7. The method for manufacturing an all-solid-state battery according to claim 6, wherein the first solid electrolyte layer of the laminate is laminated on the positive electrode layer, and the second solid electrolyte layer is laminated on the negative electrode layer.

8. The method for manufacturing an all-solid-state battery according to claim 7 , wherein the positive electrode layer and the first solid electrolyte layer of the laminate are pressure-bonded.

9. The method for manufacturing an all-solid-state battery according to claim 7 or 8, wherein the negative electrode layer and the second solid electrolyte layer of the laminate are pressure-bonded to each other.

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