Method for manufacturing solid-state battery

Abstract

The present invention addresses the problem of providing a method for manufacturing a solid-state battery capable of suppressing the occurrence of pinholes in an intermediate layer. In order to solve the problem, the present invention provides a method for manufacturing a solid-state battery having an electrode laminate in which a negative electrode layer, an intermediate layer, a solid electrolyte layer, and a positive electrode layer are laminated in this order, the intermediate layer having a first intermediate layer and a second intermediate layer, the method for manufacturing a solid-state battery includes: a first step of laminating a negative electrode layer and a first intermediate layer to obtain a first intermediate layer-negative electrode layer laminate; a second step for obtaining an intermediate layer-negative electrode layer laminate by laminating the first intermediate layer-negative electrode layer laminate and the second intermediate layer; and a third step in which a solid electrolyte layer-intermediate layer-negative electrode layer laminate is obtained by disposing and laminating a substance that constitutes the solid electrolyte layer on the lamination surface of the intermediate layer in the intermediate layer-negative electrode layer laminate.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a solid battery. Background Art

[0002] In recent years, research and development of secondary batteries that contribute to improving energy efficiency have been underway to ensure that more people have access to affordable, reliable, sustainable, and advanced energy.

[0003] As such secondary batteries, solid batteries such as lithium metal batteries and lithium ion secondary batteries are known, in which a solid electrolyte layer is arranged between a positive electrode layer and a negative electrode layer.

[0004] As a technology related to solid batteries, an all-solid-state battery is disclosed, which arranges multiple composite carbon layers with different adhesive contents between the solid electrolyte membrane and the negative electrode, and utilizes the generated voltage difference to deposit lithium in opposite directions between the composite carbon layers, thereby improving the life characteristics (for example, refer to Patent Document 1).

[0005] [Prior Art Literature]

[0006] (Patent Document)

[0007] Patent Document 1: International Publication No. 2023 / 219283 Summary of the Invention

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

[0009] However, the layer (intermediate layer) between the solid electrolyte layer and the negative electrode is composed of a material with very small particle sizes. Furthermore, the intermediate layer must be thin, which can lead to the formation of pinholes. Pinholes in the intermediate layer can cause dendrites to form within the pinholes, creating a problem.

[0010] The present invention has been made in view of the above, and an object of the present invention is to provide a method for manufacturing a solid battery capable of suppressing the generation of pinholes in an intermediate layer.

[0011] [Technical means to solve the problem]

[0012] (1) A method for manufacturing a solid battery, wherein the fixed battery has an electrode laminate, and the electrode laminate is formed by laminating a negative electrode layer, an intermediate layer, a solid electrolyte layer and a positive electrode layer in sequence, and the intermediate layer has a first intermediate layer and a second intermediate layer. The method for manufacturing the solid battery comprises: a first step of pressing the negative electrode layer and the first intermediate layer to obtain a first intermediate layer-negative electrode layer laminate; a second step of pressing the first intermediate layer-negative electrode layer laminate and the second intermediate layer to obtain an intermediate layer-negative electrode layer laminate; and a third step of arranging and pressing a substance constituting the solid electrolyte layer on the laminated surface of the intermediate layer in the intermediate layer-negative electrode layer laminate to obtain a solid electrolyte layer-intermediate layer-negative electrode layer laminate.

[0013] According to the invention of (1), a method for manufacturing a solid battery can be provided, which can suppress the generation of pinholes in the intermediate layer.

[0014] (2) A method for manufacturing a solid battery according to (1), wherein, before the second step, a 1A step is included, wherein the second intermediate layer is pressed in the 1A step, and the pressing pressure in the 1A step is higher than the pressing pressures in the first step and the second step.

[0015] According to the invention of (2), the formation of dendrites can be suppressed by increasing the density of the second intermediate layer.

[0016] (3) The method for manufacturing a solid battery according to (1) or (2), wherein the pressing pressure in the third step is higher than the pressing pressures in the first step and the second step.

[0017] According to the invention of (3), the density of the solid electrolyte layer can be increased.

[0018] (4) A method for manufacturing a solid battery according to any one of (1) to (3), wherein the method for manufacturing a solid battery includes a fourth step, wherein the fourth step is to press the aforementioned solid electrolyte layer-intermediate layer-negative electrode layer laminate with a layer including at least the aforementioned positive electrode layer to obtain an electrode laminate, and the pressing pressure in the aforementioned fourth step is higher than the pressing pressure in the aforementioned first step and the aforementioned second step.

[0019] According to the invention of (4), each layer can be preferably integrated to obtain an electrode laminate.

[0020] (5) The method for manufacturing a solid battery according to (4), wherein the pressing pressure in the fourth step is lower than the pressing pressure in the third step.

[0021] According to the invention of (5), each layer can be preferably integrated to obtain an electrode laminate.

[0022] (6) A method for manufacturing a solid battery according to (4) or (5), wherein, before the aforementioned fourth step, a 3A step is included, wherein the 3A step presses a layer including the aforementioned positive electrode layer, and the pressing pressure in the aforementioned 3A step is higher than the pressing pressure in the aforementioned fourth step.

[0023] According to the invention of (6), the battery capacity can be increased by densifying the positive electrode layer.

[0024] (7) A method for manufacturing a solid battery according to any one of (4) to (6), wherein the fourth step is a step of arranging and pressing a second solid electrolyte layer between the solid electrolyte layer-intermediate layer-negative electrode layer laminate serving as the first solid electrolyte layer and a layer including the positive electrode layer to obtain an electrode laminate.

[0025] According to the invention of (7), the bonding property between the intermediate layer and the solid electrolyte layer can be improved.

[0026] (8) A method for manufacturing a solid battery according to (7), wherein the fourth step is a step of pressing the solid electrolyte layer-intermediate layer-negative electrode layer laminate as the first solid electrolyte layer with the solid electrolyte layer-positive electrode layer laminate including the positive electrode layer and the third solid electrolyte layer to obtain an electrode laminate.

[0027] According to the invention of (8), the bonding property between the intermediate layer and the solid electrolyte layer can be improved.

[0028] (9) The method for producing a solid battery according to any one of (1) to (8), wherein the layers are pressed together so that the porosity of the second intermediate layer becomes 40% to 45%.

[0029] According to the invention of (9), the formation of dendrites can be suppressed by increasing the density of the second intermediate layer.

[0030] (10) A method for manufacturing a solid battery according to any one of (1) to (9), wherein the layers are pressed together in such a manner that the porosity of the first intermediate layer is greater than or equal to the porosity of the second intermediate layer and the porosity is less than 50%.

[0031] According to the invention of (10), the first intermediate layer can easily fill the gaps in the second intermediate layer, thereby preventing pinholes from penetrating the entire intermediate layer.

[0032] (11) A method for manufacturing a solid battery according to any one of (1) to (10), wherein the pressing pressure in the first step is 300 MPa or more, the pressing pressure in the second step is 300 MPa or more and 600 MPa or less, and the pressing pressure in the third step is 500 MPa or more and 800 MPa or less.

[0033] According to the invention of (11), the generation of pinholes in the intermediate layer can be suppressed, and at the same time, each layer can be preferably constructed to obtain an electrode laminate.

[0034] (12) The method for manufacturing a solid battery according to (2), wherein the pressing pressure in the step 1A is 600 MPa or more and 1200 MPa or less.

[0035] According to the invention of (12), the formation of dendrites can be suppressed by increasing the density of the second intermediate layer.

[0036] (13) The method for manufacturing a solid battery according to (4), wherein the pressing pressure in the fourth step is 500 MPa or more and 900 MPa or less.

[0037] According to the invention of (13), each layer can be preferably integrated to obtain an electrode laminate.

[0038] (14) The method for manufacturing a solid battery according to (2), wherein the temperature during pressing in the step 1A is higher than room temperature and lower than 100°C.

[0039] According to the invention of (14), the formation of dendrites can be suppressed by increasing the density of the second intermediate layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a conceptual cross-sectional view showing the structure of a solid state battery according to an embodiment of the present invention.

[0041] Figure 2A It is a diagram showing a part of the process in the method for manufacturing a solid battery according to the embodiment of the present invention.

[0042] Figure 2B It is a diagram showing a part of the process in the method for manufacturing a solid battery according to the embodiment of the present invention.

[0043] Figure 2C It is a diagram showing a part of the process in the method for manufacturing a solid battery according to the embodiment of the present invention.

[0044] Figure 2D It is a diagram showing a part of the process in the method for manufacturing a solid battery according to the embodiment of the present invention.

[0045] Figure 2E It is a diagram showing a part of the process in the method for manufacturing a solid battery according to the embodiment of the present invention.

[0046] Figure 2FIt is a diagram showing a part of the process in the method for manufacturing a solid battery according to the embodiment of the present invention. DETAILED DESCRIPTION

[0047] [Solid-state battery]

[0048] like Figure 1 As shown, the solid battery 1 manufactured by the manufacturing method of the present invention has an electrode laminate, which is formed by laminating a negative electrode layer 2, an intermediate layer (a first intermediate layer 51 and a second intermediate layer 52), a solid electrolyte layer 4 and a positive electrode layer 3 in this order. Figure 1 The structure shown, consisting of the negative electrode layer 2, the first intermediate layer 51, the second intermediate layer 52, the solid electrolyte layer 4, the positive electrode layer 3, the solid electrolyte layer 4, the second intermediate layer 52, the first intermediate layer 51, and the negative electrode layer 2, is described as the laminated structure of the solid battery 1. However, the structure of the solid battery 1 is not limited to the above structure, and any structure may be employed in which the negative electrode layer 2, the intermediate layers (the first intermediate layer 51 and the second intermediate layer 52), the solid electrolyte layer 4, and the positive electrode layer 3 are laminated in this order.

[0049] The solid battery 1 is not particularly limited and may be a lithium ion solid secondary battery or a lithium metal secondary battery.

[0050] (Negative electrode layer)

[0051] The negative electrode layer 2 has a negative electrode active material layer 21 and a negative electrode current collector layer 22. The negative electrode active material layer 21 is not particularly limited and can be composed of a material that can be used as a negative electrode active material for a solid battery. The negative electrode active material layer 21 is preferably a lithium metal layer in which the negative electrode active material is lithium metal. This is because even if the negative electrode active material layer 21 is a hard metal, the solid battery 1 of the present invention can be tightly bonded to the solid electrolyte layer 4 with high adhesion. The above-mentioned lithium metals include lithium alloys in addition to lithium metal monomers. In addition to the above, the negative electrode active material layer 21 can also be made 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.

[0052] In addition to the above, the negative electrode active material layer 21 may also contain materials that can be contained in the negative electrode active material layer of a solid battery. Examples of the above materials include solid electrolytes, conductive additives, and adhesives. Examples of solid electrolytes include the same solid electrolytes as those contained in the solid electrolyte layer 4 described below. Examples of conductive additives include carbon black, natural graphite, carbon fibers, and carbon nanotubes. Examples of adhesives include nitrile polymers, polyester polymers, acrylic polymers, cellulose polymers, styrene polymers, styrene-butadiene polymers, vinyl acetate polymers, polyurethane polymers, and vinyl fluoride polymers.

[0053] The negative electrode current collector layer 22 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 22 include foil, plate, mesh, nonwoven fabric, and foam. A portion of the negative electrode current collector layer 22 extends in a specific direction to form the negative electrode current collector tab 22a.

[0054] (Middle layer)

[0055] The intermediate layer is arranged between the negative electrode layer 2 and the solid electrolyte layer 4. The intermediate layer is composed of two layers: a first intermediate layer 51 arranged on the negative electrode layer 2 side and a second intermediate layer 52 arranged on the solid electrolyte layer 4 side. For example, when the solid battery 1 is a lithium metal battery, the intermediate layer has the function of uniformly precipitating lithium metal. Therefore, the interface between the intermediate layer and the solid electrolyte layer 4 is stable. When the solid battery 1 is a lithium metal secondary battery with an intermediate layer, the solid battery 1 can also be a negative electrode-free battery in which the negative electrode active material layer 21 does not exist 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 21.

[0056] The materials constituting the first intermediate layer 51 and the second intermediate layer 52 are 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), and antimony (Sb). Metals that can form alloys 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. Amorphous carbon may be easily graphitized carbon (soft carbon), difficultly graphitized carbon (hard carbon), carbon nanotubes (CNTs), fullerenes, and graphene. In addition to the above-mentioned substances, the intermediate layer may also include a binder.

[0057] The particle size (D50) of the material constituting the first intermediate layer 51 and the second intermediate layer 52 is preferably 5 to 300 nm. This particle size is preferably smaller than the particle size (D50) of the solid electrolyte material constituting the solid electrolyte layer 4 described later.

[0058] The thickness of the first intermediate layer 51 and the second intermediate layer 52 is not particularly limited, but is preferably 1 to 3 μm. By making the intermediate layers as thin as possible, the resistance of the solid battery 1 can be reduced.

[0059] If the intermediate layer with the above-mentioned particle size and layer thickness is assumed to be a single layer, pinholes are likely to be generated. By setting the intermediate layer as two layers, the first intermediate layer 51 and the second intermediate layer 52, pinholes can be suppressed from penetrating the entire intermediate layer. The second intermediate layer 52 is preferably a layer with a higher density than the first intermediate layer 51. In other words, the porosity of the second intermediate layer 52 is preferably lower than the porosity of the first intermediate layer 51. As a result, the formation of dendrites can be better suppressed by the high-density second intermediate layer 52. In addition, the bonding property with the negative electrode layer 2 is improved by the first intermediate layer 51 with a relatively low density. Furthermore, even if pinholes are generated in the high-density second intermediate layer 52, the first intermediate layer 51 can enter its gaps. As a result, the risk of pinholes penetrating the entire intermediate layer can be suppressed, thereby suppressing the formation of dendrites in the pinholes. In order to achieve the above-mentioned effect, as described later, the second intermediate layer 52 is preferably bonded to the first intermediate layer 51 after high-density pressing in advance.

[0060] The porosity of the first intermediate layer 51 is preferably greater than or equal to the porosity of the second intermediate layer 52, and more preferably greater than the porosity of the second intermediate layer 52. The porosity of the first intermediate layer 51 is preferably less than 50%, and preferably greater than 48%. The porosity of the second intermediate layer 52 is preferably 40% to 45%, and more preferably 42% to 44%. The porosity can be determined by observing cross-sections of the first intermediate layer 51 and the second intermediate layer 52 using a scanning electron microscope (SEM).

[0061] The first and second intermediate layers 51, 52 may differ in density (porosity) simply due to differences in press pressure during production, for example, and may be made of the same material. This improves the bonding between the first and second intermediate layers 51, 52.

[0062] (Solid electrolyte layer)

[0063] The solid electrolyte layer 4 is formed between the second intermediate layer 52 and the positive electrode layer 3. In this embodiment, the solid electrolyte layer 4 has a structure in which a first solid electrolyte layer 41, a second solid electrolyte layer 42, and a third solid electrolyte layer 43 arranged on the side of the positive electrode layer 3 are stacked in this order. The number of layers of the solid electrolyte layer 4 is not limited to the above number.

[0064] The first solid electrolyte layer 41 is positioned adjacent to the second intermediate layer 52. During the press-fit process, the first solid electrolyte layer 41 achieves a high density, resulting in a close bond with the second intermediate layer 52. The high density of the first solid electrolyte layer 41 and its close bond with the second intermediate layer 52 suppresses abnormal electrolysis, resulting in improved battery performance.

[0065] 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 battery. Examples include sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, inorganic solid electrolytes such as lithium salts, and polymer solid electrolytes such as polyethylene oxide. These solid electrolytes may be used alone or in combination of two or more.

[0066] The solid electrolyte material constituting the first solid electrolyte layer 41 is preferably in a granular form. The particle size (D50) of the solid electrolyte material constituting the first solid electrolyte layer 41 is preferably 10 μm or less, more preferably 3 μm or less, even more preferably 1 μm or less, and most preferably 0.7 μm or less. This facilitates increasing the density of the first solid electrolyte layer 41.

[0067] In addition to the solid electrolyte material, the first solid electrolyte layer 41 may also contain a material that can be used for a solid electrolyte layer of a solid battery. For example, the first solid electrolyte layer 41 may further contain a binder. As the binder, the same binder that can be contained in the negative electrode active material layer 21 can be used.

[0068] The second solid electrolyte layer 42 is disposed adjacent to the first solid electrolyte layer 41. The solid electrolyte material constituting the second solid electrolyte layer 42 is not particularly limited, and the same solid electrolyte material as that constituting the first solid electrolyte layer 41 can be used.

[0069] Similar to the first solid electrolyte layer 41, the second solid electrolyte layer 42 may also contain a binder, etc., in addition to the solid electrolyte material. The second solid electrolyte layer 42 may also contain a support. The support may be a three-dimensional structure such as a mesh, woven fabric, non-woven fabric, embossed material, punched material, expanded material, or foamed material. The second solid electrolyte layer 42 may not contain any of the above supports.

[0070] The third solid electrolyte layer 43 is disposed on the positive electrode layer side. In this embodiment, the third solid electrolyte layer 43 is disposed adjacent to the positive electrode active material layer 31 in the positive electrode layer 3. The third solid electrolyte layer 43 is disposed adjacent to the second solid electrolyte layer 42. That is, in this embodiment, the third solid electrolyte layer 43 is disposed between the positive electrode active material layer 31 and the second solid electrolyte layer 42.

[0071] The structure of the third solid electrolyte layer 43 can be the same as that of the first solid electrolyte layer 41. By making the third solid electrolyte layer 43 denser and closely adhering to the positive electrode active material layer 31, better battery performance such as lower resistance can be achieved.

[0072] (positive electrode layer)

[0073] The positive electrode layer 3 includes a positive electrode active material layer 31 and a positive electrode current collector layer 32. In this embodiment, the positive electrode layer 3 has a structure in which two positive electrode active material layers 31 are laminated on both sides of a positive electrode current collector layer 32. However, the structure of the positive electrode layer 3 is not limited to the above structure, and may also have a structure in which a single positive electrode active material layer 31 is laminated on a single side of a positive electrode current collector layer 32.

[0074] The positive electrode active material layer 31 is not particularly limited and can be composed of a material that can be used as a positive electrode active material for a solid battery. Examples of the positive electrode active material constituting the positive electrode active material layer 31 include LiCoO2, LiNiO2, LiCo x Ni y MnzO2 (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.)), polyaniline, 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.

[0075] An insulating frame 6 may also be provided on the periphery of the positive electrode active material layer 31. The insulating frame 6 can prevent the short circuit of the solid battery 1 and improve the strength. In the present embodiment, the insulating frame 6 is configured to cover the side surfaces of the two positive electrode active material layers 31 formed on both sides of the positive electrode collector layer 32. In addition, the insulating frame 6 abuts a portion of the laminated surface of the positive electrode collector layer 32 and has a pore for the positive electrode collector tab 32a described later to extend. There is no particular limitation on the material constituting the insulating frame 6, and examples thereof include insulating oxides such as alumina, resins such as polyvinylidene fluoride (PVDF), and rubbers such as styrene butadiene rubber (SBR).

[0076] The positive electrode current collector layer 32 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 32 include foil, sheet, mesh, non-woven fabric, and foam. A portion of the positive electrode current collector layer 32 extends in a specific direction to form the positive electrode current collector tab 32a.

[0077] [Method for manufacturing solid-state batteries]

[0078] refer to Figures 2A to 2F The following describes a method for manufacturing a solid-state battery according to this embodiment. The method comprises an electrode laminate La comprising a negative electrode layer 2, intermediate layers (a first intermediate layer 51 and a second intermediate layer 52), a solid electrolyte layer 4, and a positive electrode layer 3 stacked in this order.

[0079] The solid-state battery manufacturing method of this embodiment essentially includes: a first step of pressing the negative electrode layer 2 and the first intermediate layer 51 to form a first intermediate layer-negative electrode layer laminate L1; a second step of pressing the first intermediate layer-negative electrode layer laminate L1 and the second intermediate layer 52 to form an intermediate layer-negative electrode layer laminate L2; and a third step of placing and pressing the material constituting the solid electrolyte layer (first solid electrolyte layer 41) onto the laminated surface of the intermediate layer (second intermediate layer 52) in the intermediate layer-negative electrode layer laminate L2 to form a solid electrolyte layer-intermediate layer-negative electrode layer laminate L3. The pressing temperature in each pressing step can be set to room temperature (approximately 25°C).

[0080] like Figure 2BAs shown, the first step is to arrange and press-bond the first intermediate layer 51 onto the surface of the negative electrode layer 2 facing the negative electrode active material layer 21. Specifically, a method for arranging the first intermediate layer 51 onto the surface facing the negative electrode active material layer 21 is by transfer using an intermediate layer transfer sheet. The intermediate layer transfer sheet is obtained, for example, by applying a slurry containing the materials constituting the first intermediate layer 51 dispersed in a solvent onto a support sheet and drying the slurry.

[0081] The pressure used to press the negative electrode layer 2 and the first intermediate layer 51 in the first step is not particularly limited, as long as the negative electrode layer 2 and the intermediate layer 5 can be bonded together without excessive deformation of the layers and without separation in subsequent steps. The pressing pressure in the first step is, for example, in the range of 300 MPa or greater.

[0082] like Figure 2C As shown, the second step is a step of placing and pressing the second intermediate layer 52 on the surface of the first intermediate layer-negative electrode layer laminate L1 on the first intermediate layer 51 side. The second intermediate layer 52 can be formed into a sheet in advance.

[0083] The pressure at which the first intermediate layer-negative electrode layer laminate L1 and the second intermediate layer 52 are pressed in the second step is, for example, in the range of 300 MPa to 600 MPa.

[0084] like Figure 2A As shown, the manufacturing method of the solid battery of this embodiment preferably includes a 1A step of pressing the second intermediate layer 52 before the second step. By pre-pressing the second intermediate layer 52 in the 1A step to increase its density, the porosity of the second intermediate layer 52 can be set within a preferred range, thereby suppressing the formation of dendrites. Figure 2A As shown, step 1A can be performed, for example, by pressing the second intermediate layer 52 formed on the support sheet S. The second intermediate layer 52 can be peeled off from the support sheet S after step 1A, or the support sheet S can be peeled off from the laminate obtained after the second step. The timing of performing step 1A is not particularly limited as long as it is before the second step.

[0085] The pressure at which the second intermediate layer 52 is pressed in step 1A is preferably higher than the pressing pressure in steps 1 and 2. This allows the density of the second intermediate layer 52 to be increased. The pressing pressure in step 1A is, for example, within a range of 600 MPa to 1200 MPa. The pressing temperature in step 1A is preferably above room temperature and below 100°C. Room temperature is, for example, 25°C. This pressing temperature allows the density of the intermediate layer to be preferably increased.

[0086] like Figure 2DAs shown in FIG. 1 , the third step is to arrange and press-bond the solid electrolyte layer on the surface of the intermediate layer-negative electrode layer laminate L2 on the second intermediate layer 52 side. Figure 2D In the figure, the first solid electrolyte layer 41 of the three-layer solid electrolyte layer 4 is shown as the solid electrolyte layer, but the solid electrolyte layer can also be a single layer. When using a three-layer solid electrolyte layer 4, the solid electrolyte layer pressed in the third step is preferably the first solid electrolyte layer 41 (i.e., one of the three solid electrolyte layers). The solid electrolyte layer can be arranged using a solid electrolyte transfer sheet similar to the intermediate layer transfer sheet described above, or using a preformed solid electrolyte sheet.

[0087] The pressure used to press the intermediate layer-negative electrode layer laminate L2 and the solid electrolyte layer in the third step is preferably higher than the pressing pressure used in the first and second steps. This allows for a higher density of the solid electrolyte layer. The pressing pressure in the third step is, for example, within a range of 500 MPa to 800 MPa.

[0088] like Figure 2F As shown, the method for manufacturing a solid battery of this embodiment preferably includes a fourth step of laminating the following layers to obtain an electrode laminate La, the layers including a solid electrolyte layer-intermediate layer-negative electrode layer laminate L3 and a layer including at least a positive electrode layer 3. In each figure, the layer including at least the positive electrode layer 3 is a solid electrolyte layer-positive electrode layer laminate L4 formed by laminating the positive electrode layer 3 and the third solid electrolyte layer 43, but the present invention is not limited to this configuration.

[0089] The fourth step is preferably a step in which the second solid electrolyte layer 42 is arranged so as to face each solid electrolyte layer and is pressed between the solid electrolyte layer-intermediate layer-negative electrode layer laminate L3 and the solid electrolyte layer-positive electrode layer laminate L4 to obtain the electrode laminate La. As the second solid electrolyte layer 42, for example, a solid electrolyte layer pre-formed into a sheet can be used. In this embodiment, the solid electrolyte layer-positive electrode layer laminate L4 has a third solid electrolyte layer 43 on both sides. Therefore, two second solid electrolyte layers 42 are arranged so as to face each other on both sides of the solid electrolyte layer-positive electrode layer laminate L4, and each layer is further arranged so as to be sandwiched between the two solid electrolyte layer-intermediate layer-negative electrode layer laminates L3. Assuming that the solid electrolyte layer-positive electrode layer laminate L4 has the third solid electrolyte layer 43 only on one side, one second solid electrolyte layer 42 can be arranged so as to face the third solid electrolyte layer 43, and one solid electrolyte layer-intermediate layer-negative electrode layer laminate L3 can be further arranged.

[0090] The fourth step integrates the layers, so the pressure is preferably set to a level that does not cause excessive deformation of the layers. From this perspective, the pressing pressure in the fourth step is preferably higher than the pressing pressures in the first and second steps, and lower than the pressing pressure in the third step. The pressing pressure in the fourth step is, for example, within the range of 500 MPa to 900 MPa.

[0091] like Figure 2E As shown, the manufacturing method of the solid battery of this embodiment preferably includes a 3A step before the fourth step, wherein the 3A step presses the layers including the positive electrode layer 3. For example, Figure 2E As shown, the 3A process is a process in which the material constituting the third solid electrolyte layer 43 is arranged and pressed on the laminated surface of the positive electrode layer 3 to obtain a solid electrolyte layer-positive electrode layer laminate L4. The 3A process is not limited to the above, and it can also be a process in which only the positive electrode layer 3 is pressed. In this embodiment, the positive electrode layer 3 is formed with a positive electrode active material layer 31 on both sides of the positive electrode current collector layer 32, and the third solid electrolyte layer 43 is arranged on the two positive electrode active material layers 31. Assuming that the positive electrode layer 3 is formed with a positive electrode active material layer 31 only on one side of the positive electrode current collector layer 32, the third solid electrolyte layer 43 can be arranged on a single positive electrode active material layer 31. The method for arranging the third solid electrolyte layer 43 can be the same as the third process.

[0092] The pressure at which the layers including the positive electrode layer 3 are pressed in step 3A is preferably higher than the pressing pressure in step 4, which integrates the layers. This allows for a higher density of the layers including the positive electrode layer 3. The pressing pressure in step 3A is, for example, within a range of 700 MPa to 1200 MPa.

[0093] In each of the above steps, there is no particular limitation on the device for lamination, and a roller press or a flat plate press can be used. When a roller press is used for lamination, the direction in which the object to be laminated is conveyed to the roller press can be the same direction or different directions. For example, the direction in which the object is conveyed to the roller press in the third step and the 3A step can be different from or orthogonal to the direction in which the object is conveyed to the roller press in the fourth step. As a result, the layers with lower Young's modulus of each layer extend in one direction, making it less likely that defects will occur in the solid electrolyte layer 4 due to stretching of the solid electrolyte layer 4.

[0094] 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 electrode laminate shown, the solid battery 1 may have a structure applicable to the solid battery, such as an outer package. The method for manufacturing a solid battery may have any steps other than those described above.

[0095] Reference numerals

[0096] 1Solid-state battery

[0097] 2 negative electrode layer

[0098] 3 positive electrode layer

[0099] 4 Solid electrolyte layer

[0100] 41First solid electrolyte layer

[0101] 42 Second solid electrolyte layer

[0102] 43 Third solid electrolyte layer

[0103] 51 First Intermediate Layer

[0104] 52 Second middle layer

[0105] L1 first intermediate layer-negative electrode layer laminate

[0106] L2 Intermediate layer-negative electrode layer laminate

[0107] L3 solid electrolyte layer-intermediate layer-negative electrode layer laminate

[0108] La electrode laminate

Claims

1. A method for manufacturing a solid battery, wherein the solid battery comprises an electrode laminate, wherein the electrode laminate is formed by laminating a negative electrode layer, an intermediate layer, a solid electrolyte layer, and a positive electrode layer in this order; The intermediate layer comprises a first intermediate layer and a second intermediate layer. The manufacturing method of the solid battery comprises: The first step is to press the negative electrode layer and the first intermediate layer together to obtain a first intermediate layer-negative electrode layer laminate; The second step is to press the first intermediate layer-negative electrode layer laminate and the second intermediate layer to obtain an intermediate layer-negative electrode layer laminate; and In the third step, a material constituting the solid electrolyte layer is arranged and press-bonded on the laminated surface of the intermediate layer in the intermediate layer-negative electrode layer laminate to obtain a solid electrolyte layer-intermediate layer-negative electrode layer laminate.

2. The method for manufacturing a solid battery according to claim 1, wherein: Before the second step, the method includes a 1A step of pressing the second intermediate layer. The pressing pressure in the aforementioned step 1A is higher than the pressing pressures in the aforementioned first step and the aforementioned second step.

3. The method for manufacturing a solid battery according to claim 1 or 2, wherein: The pressing pressure in the third step is higher than the pressing pressures in the first and second steps.

4. The method for manufacturing a solid battery according to claim 1 or 2, wherein: The method for manufacturing a solid battery includes a fourth step of laminating the solid electrolyte layer-intermediate layer-negative electrode layer laminate with a layer including at least the positive electrode layer to obtain an electrode laminate. The pressing pressure in the fourth step is higher than the pressing pressures in the first and second steps.

5. The method for manufacturing a solid battery according to claim 4, wherein: The pressing pressure in the fourth step is lower than the pressing pressure in the third step.

6. The method for manufacturing a solid battery according to claim 4, wherein: Before the fourth step, a 3A step is included, wherein the 3A step is to press the layer including the positive electrode layer. The pressing pressure in the aforementioned step 3A is higher than the pressing pressure in the aforementioned step 4.

7. The method for manufacturing a solid battery according to claim 4, wherein: The fourth step is a step of arranging and press-bonding the second solid electrolyte layer between the solid electrolyte layer-intermediate layer-negative electrode layer laminate as the first solid electrolyte layer and the layer including the positive electrode layer to obtain an electrode laminate.

8. The method for manufacturing a solid battery according to claim 7, wherein: The fourth step is a step of press-bonding the solid electrolyte layer-intermediate layer-negative electrode layer laminate as the first solid electrolyte layer and the solid electrolyte layer-positive electrode layer laminate including the positive electrode layer and the third solid electrolyte layer to obtain an electrode laminate.

9. The method for manufacturing a solid battery according to claim 1 or 2, wherein: The layers were laminated together so that the porosity of the second intermediate layer became 40% to 45%.

10. The method for manufacturing a solid battery according to claim 1 or 2, wherein: The layers are laminated so that the porosity of the first intermediate layer is equal to or greater than that of the second intermediate layer and is less than 50%.

11. The method for manufacturing a solid battery according to claim 1 or 2, wherein: The pressing pressure in the first step is 300 MPa or more. The pressing pressure in the second step is 300 MPa or more and 600 MPa or less. The pressing pressure in the third step is 500 MPa or more and 800 MPa or less.

12. The method for manufacturing a solid battery according to claim 2, wherein: The pressing pressure in the aforementioned step 1A is 600 MPa or more and 1200 MPa or less.

13. The method for manufacturing a solid battery according to claim 4, wherein: The pressing pressure in the fourth step is 500 MPa or more and 900 MPa or less.

14. The method for manufacturing a solid battery according to claim 2, wherein: The temperature during the pressing in the aforementioned step 1A is higher than room temperature and lower than 100°C.

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