Method for manufacturing solid-state battery

Abstract

To provide a method for manufacturing a solid-state battery capable of suppressing the occurrence of pinholes in an intermediate layer.SOLUTION: In a method for manufacturing a solid-state battery having an electrode laminate in which an anode layer, an intermediate layer, a solid electrolyte layer, and a cathode layer are laminated in this order, the intermediate layer has a first intermediate layer and a second intermediate layer, and the method includes a first step of press-bonding the anode layer and the first intermediate layer to obtain a first intermediate layer-anode layer laminate, a second step of press-bonding the first intermediate layer-anode layer laminate and the second intermediate layer to obtain an intermediate layer-anode layer laminate, and a third step of arranging a material that forms a solid electrolyte layer on a laminate surface of the intermediate layer in the intermediate layer-anode layer laminate and press-bonding them to obtain a solid electrolyte layer-intermediate layer-anode layer laminate.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

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

[0003] Known examples of such secondary batteries include solid-state batteries such as lithium metal batteries and lithium ion secondary batteries, in which a solid electrolyte layer is disposed between a positive electrode layer and a negative electrode layer.

[0004] As a technology related to solid-state batteries, an all-solid-state battery has been disclosed in which multiple composite carbon layers with different binder contents are provided between a solid electrolyte membrane and a negative electrode, and lithium is precipitated in opposing directions between the composite carbon layers due to the difference in generated voltage, thereby improving the life characteristics (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2023 / 219283 Summary of the Invention [Problem to be solved by the invention]

[0006] The layer (intermediate layer) between the solid electrolyte layer and the negative electrode is made of a material with very small particle size. Furthermore, because the intermediate layer is required to be thin, pinholes may form in the intermediate layer. If pinholes form in the intermediate layer, they can cause problems because dendrites may form within the pinholes.

[0007] The present invention has been made in view of the above, and has an object to provide a method for manufacturing a solid-state battery that can suppress the occurrence of pinholes in the intermediate layer. [Means for solving the problem]

[0008] (1) A method for manufacturing a solid-state battery having an electrode laminate in which an anode layer, an intermediate layer, a solid electrolyte layer, and a cathode layer are laminated in this order, the intermediate layer having a first intermediate layer and a second intermediate layer, the method comprising: a first step of press-bonding the anode layer and the first intermediate layer to obtain a first intermediate layer-anode layer laminate; a second step of press-bonding the first intermediate layer-anode layer laminate and the second intermediate layer to obtain an intermediate layer-anode layer laminate; and a third step of arranging a material constituting the solid electrolyte layer on a laminate surface of the intermediate layer in the intermediate layer-anode layer laminate and press-bonding the material to obtain a solid electrolyte layer-intermediate layer-anode layer laminate.

[0009] According to the invention (1), it is possible to provide a method for manufacturing a solid-state battery that can suppress the occurrence of pinholes in the intermediate layer.

[0010] (2) The method for producing a solid-state battery according to (1), further comprising a step 1A of pressing the second intermediate layer before the step 2, wherein the pressing pressure in the step 1A is higher than the pressing pressures in the steps 1 and 2.

[0011] According to the invention of (2), the second intermediate layer is densified, thereby making it possible to suppress the formation of dendrites.

[0012] (3) The method for producing a solid-state battery according to (1) or (2), wherein the pressing pressure in the third step is higher than the pressing pressure in the first step and the second step.

[0013] According to the invention (3), the solid electrolyte layer can be made denser.

[0014] (4) The method for producing a solid state battery according to any one of (1) to (3), further comprising a fourth step of press-bonding the solid electrolyte layer-intermediate layer-negative electrode layer stack and a layer including at least the positive electrode layer to obtain an electrode stack, wherein the press pressure in the fourth step is higher than the press pressures in the first step and the second step.

[0015] According to the invention (4), the layers can be preferably integrated to obtain an electrode laminate.

[0016] (5) The method for producing a solid-state battery according to (4), wherein the pressing pressure in the fourth step is lower than the pressing pressure in the third step.

[0017] According to the fifth aspect of the present invention, the layers can be preferably integrated to obtain an electrode laminate.

[0018] (6) A step 3A of pressing the layer including the positive electrode layer is included before the step 4, The method for producing a solid state battery according to (4) or (5), wherein the pressing pressure in the step 3A is higher than the pressing pressure in the step 4.

[0019] According to the invention of (6), the battery capacity can be improved by densifying the positive electrode layer.

[0020] (7) The method for producing a solid state battery according to any one of (4) to (6), wherein the fourth step is a step of disposing a second solid electrolyte layer between the solid electrolyte layer-intermediate layer-negative electrode layer stack as a first solid electrolyte layer and a layer including the positive electrode layer, and press-bonding the resulting layers to obtain an electrode stack.

[0021] According to the seventh aspect of the present invention, the bonding strength between the intermediate layer and the solid electrolyte layer can be improved.

[0022] (8) The method for producing a solid state battery according to (7), wherein the fourth step is a step of press-bonding the solid electrolyte layer-intermediate layer-negative electrode layer stack as a first solid electrolyte layer and a solid electrolyte layer-cathode layer stack including the positive electrode layer and a third solid electrolyte layer to obtain an electrode stack.

[0023] According to the invention (8), the bonding strength between the intermediate layer and the solid electrolyte layer can be improved.

[0024] (9) The method for producing a solid state battery according to any one of (1) to (8), wherein the layers are press-bonded together so that the porosity of the second intermediate layer is 40% to 45%.

[0025] According to the invention of (9), the second intermediate layer is densified, so that the formation of dendrites can be suppressed.

[0026] (10) The method for producing a solid state battery according to any one of (1) to (9), wherein the layers are press-bonded together so that the porosity of the first intermediate layer is equal to or greater than the porosity of the second intermediate layer and is less than 50%.

[0027] According to the invention (10), the first intermediate layer can easily fill gaps in the second intermediate layer, and pinholes can be prevented from penetrating the entire intermediate layer.

[0028] (11) The method for producing a solid state 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.

[0029] According to the invention (11), it is possible to obtain an electrode laminate with each layer preferably configured while suppressing the occurrence of pinholes in the intermediate layer.

[0030] (12) The method for producing a solid state battery according to (2), wherein the pressing pressure in the step 1A is 600 MPa or more and 1200 MPa or less.

[0031] According to the invention of (12), the second intermediate layer is densified, so that the formation of dendrites can be suppressed.

[0032] (13) The method for producing a solid state battery according to (4), wherein the pressing pressure in the fourth step is 500 MPa or more and 900 MPa or less.

[0033] According to the invention (13), the layers can be preferably integrated to obtain an electrode laminate.

[0034] (14) The method for producing a solid-state battery according to (2), wherein the temperature during pressing in the step 1A is equal to or higher than room temperature and equal to or lower than 100°C.

[0035] According to the invention of (14), the second intermediate layer is densified, so that the formation of dendrites can be suppressed. [Brief explanation of the drawings]

[0036] [Figure 1] 1 is a conceptual cross-sectional view showing the configuration of a solid-state battery according to an embodiment of the present invention. [Figure 2A] 1A to 1C are diagrams illustrating some steps in a method for manufacturing a solid-state battery according to an embodiment of the present invention. [Figure 2B] 1A to 1C are diagrams illustrating some steps in a method for manufacturing a solid-state battery according to an embodiment of the present invention. [Figure 2C] 1A to 1C are diagrams illustrating some steps in a method for manufacturing a solid-state battery according to an embodiment of the present invention. [Figure 2D] 1A to 1C are diagrams illustrating some steps in a method for manufacturing a solid-state battery according to an embodiment of the present invention. [Figure 2E] 1A to 1C are diagrams illustrating some steps in a method for manufacturing a solid-state battery according to an embodiment of the present invention. [Figure 2F] 1A to 1C are diagrams illustrating some steps in a method for manufacturing a solid-state battery according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0037] [Solid battery] As shown in FIG. 1 , a solid-state battery 1 manufactured by the manufacturing method according to the present invention has an electrode laminate in which an anode layer 2, intermediate layers (a first intermediate layer 51 and a second intermediate layer 52), a solid electrolyte layer 4, and a cathode layer 3 are laminated in this order. In this embodiment, the structure in which the anode layer 2, the first intermediate layer 51, the second intermediate layer 52, the solid electrolyte layer 4, the cathode layer 3, the solid electrolyte layer 4, the second intermediate layer 52, the first intermediate layer 51, and the anode layer 2 are laminated in this order will be described as the laminate structure of the solid-state battery 1. However, the structure of the solid-state battery 1 is not limited to the above, and it is sufficient that the solid-state battery 1 has a structure in which the anode layer 2, intermediate layers (the first intermediate layer 51 and the second intermediate layer 52), the solid electrolyte layer 4, and the cathode layer 3 are laminated in this order.

[0038] The solid state battery 1 is not particularly limited, but may be a lithium ion solid state secondary battery or a lithium metal secondary battery.

[0039] (negative electrode layer) The anode layer 2 has an anode active material layer 21 and an anode current collector layer 22. The anode active material layer 21 is not particularly limited and can be made of a material that can be used as an anode active material for a solid-state battery. The anode active material layer 21 is preferably a lithium metal layer in which the anode active material is lithium metal. This is because, in the solid-state battery 1 according to the present invention, even if the anode active material layer 21 is made of a hard metal, it can adhere to the solid electrolyte layer 4 with high adhesion. The lithium metal includes not only elemental lithium metal but also lithium alloys, etc. The anode active material layer 21 can also be made of silicon-based active materials such as Si and Si alloys, lithium titanate (Li4Ti5O 12 The electrode may be composed of lithium transition metal oxides such as TiO2, Nb2O3 and WO3, metal sulfides, metal nitrides, carbon materials such as graphite, soft carbon and hard carbon, metallic indium, etc.

[0040] The negative electrode active material layer 21 may contain other materials that can be contained in a negative electrode active material layer of a solid-state battery. Examples of such materials include a solid electrolyte, a conductive additive, and a binder. Examples of the solid electrolyte include the same solid electrolyte contained in the solid electrolyte layer 4 described below. Examples of the conductive additive include carbon black, natural graphite, carbon fiber, and carbon nanotubes. Examples of the binder include a nitrile polymer, a polyester polymer, an acrylic acid polymer, a cellulose polymer, a styrene polymer, a styrene-butadiene polymer, a vinyl acetate polymer, a urethane polymer, and a fluoroethylene polymer.

[0041] The negative electrode current collector layer 22 is not particularly limited, but may be made of copper, nickel, stainless steel, or the like. Examples of the shape of the negative electrode current collector layer 22 include foil, plate, mesh, nonwoven fabric, and foam. A portion of the negative electrode current collector layer 22 extends in a predetermined direction to form a negative electrode current collector tab 22a.

[0042] (middle class) The intermediate layer is disposed between the anode layer 2 and the solid electrolyte layer 4. The intermediate layer is composed of two layers: a first intermediate layer 51 disposed on the anode layer 2 side, and a second intermediate layer 52 disposed 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 depositing lithium metal. Therefore, the interface between the intermediate layer and the solid electrolyte layer 4 is stabilized. When the solid battery 1 is a lithium metal secondary battery having an intermediate layer, the solid battery 1 may be an anode-free battery in which the anode active material layer 21 is not present during the initial charge. In this case, a lithium metal layer is formed as the anode active material layer 21 after the initial charge / discharge.

[0043] The materials constituting the first intermediate layer 51 and the second intermediate layer 52 are not particularly limited, and examples thereof include metals capable of forming an alloy with lithium and amorphous carbon. Examples of metals capable of forming an alloy with lithium include tin (Sn), silicon (Si), zinc (Zn), magnesium (Mg), gold (Au), platinum (Pt), palladium (Pd), silver (Ag), aluminum (Al), bismuth (Bi), and antimony (Sb). The metals capable of forming an alloy with lithium may be nanoparticles. Examples of amorphous carbon include carbon blacks such as acetylene black, furnace black, and ketjen black, coke, and activated carbon. The amorphous carbon may be graphitizable carbon (soft carbon), non-graphitizable carbon (hard carbon), CNT (carbon nanotube), fullerene, or graphene. The intermediate layer may contain a binder in addition to the above materials.

[0044] The particle size (D50) of the substance constituting the first intermediate layer 51 and the second intermediate layer 52 is preferably 5 to 300 nm. The particle size is preferably smaller than the particle size (D50) of the solid electrolyte material constituting the solid electrolyte layer 4, which will be described later.

[0045] There are no particular limitations on the thickness of the first intermediate layer 51 and the second intermediate layer 52, but each is preferably 1 to 3 μm. By configuring the intermediate layers to be as thin as possible, the resistance of the solid state battery 1 can be reduced.

[0046] If an intermediate layer having the above particle size and thickness were formed as a single layer, pinholes would be prone to occur. By forming the intermediate layer into two layers, the first intermediate layer 51 and the second intermediate layer 52, pinholes can be prevented 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 equal to or lower than the porosity of the first intermediate layer 51. This allows the densified second intermediate layer 52 to preferably suppress the formation of dendrites. Furthermore, the relatively low density of the first intermediate layer 51 improves the bonding strength with the negative electrode layer 2. Furthermore, even if pinholes occur in the densified second intermediate layer 52, the first intermediate layer 51 can penetrate into the gaps. This reduces the risk of pinholes penetrating the entire intermediate layer, thereby preventing dendrites from forming in the pinholes. To achieve the above effects, the second intermediate layer 52 is preferably bonded to the first intermediate layer 51 after being subjected to densification pressing in advance, as described below.

[0047] The porosity of the first intermediate layer 51 is preferably equal to or greater than 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 48% or greater. The porosity of the second intermediate layer 52 is preferably 40% to 45%, and more preferably 42% to 44%. The porosities can be determined by observing cross sections of the first intermediate layer 51 and the second intermediate layer 52 using an SEM or the like.

[0048] The first intermediate layer 51 and the second intermediate layer 52 may be made of the same material, although their densities (porosities) differ due to, for example, different press pressures used during production. This improves the bonding between the first intermediate layer 51 and the second intermediate layer 52.

[0049] (solid electrolyte layer) 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 arranged on the second intermediate layer 52 side, a second solid electrolyte layer 42, and a third solid electrolyte layer 43 arranged on the positive electrode layer 3 side are stacked in this order. The number of layers in the solid electrolyte layer 4 is not limited to the above.

[0050] The first solid electrolyte layer 41 is disposed adjacent to the second intermediate layer 52. The first solid electrolyte layer 41 is densified during the press-bonding process and adheres closely to the second intermediate layer 52. The densification of the first solid electrolyte layer 41 and its adhesion to the second intermediate layer 52 can suppress the occurrence of abnormal electrodeposition. Furthermore, favorable battery performance can be obtained.

[0051] The solid electrolyte material constituting the first solid electrolyte layer 41 is not particularly limited, and may be any material that can be used as an electrolyte in a solid-state battery. Examples include inorganic solid electrolytes such as sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, and lithium-containing salts, and polymer solid electrolytes such as polyethylene oxide. The above solid electrolytes may be used alone or in combination of two or more.

[0052] The solid electrolyte material constituting the first solid electrolyte layer 41 is preferably in a particulate 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 allows the first solid electrolyte layer 41 to be easily densified.

[0053] In addition to the solid electrolyte material, the first solid electrolyte layer 41 may contain a material that can be used in a solid electrolyte layer of a solid-state battery. For example, the first solid electrolyte layer 41 may contain a binder. As the binder, a material similar to the binder that can be contained in the negative electrode active material layer 21 can be used.

[0054] 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 may be the same material as the solid electrolyte material constituting the first solid electrolyte layer 41.

[0055] Like the first solid electrolyte layer 41, the second solid electrolyte layer 42 may contain a binder or the like 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, a woven fabric, a nonwoven fabric, an embossed body, a punched body, an expanded body, or a foamed body. The second solid electrolyte layer 42 may not contain the support.

[0056] 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.

[0057] The configuration of the third solid electrolyte layer 43 can be the same as the configuration of the first solid electrolyte layer 41. The third solid electrolyte layer 43 is densified and adheres closely to the positive electrode active material layer 31, thereby achieving favorable battery performance such as low resistance.

[0058] (positive electrode layer) The positive electrode layer 3 has 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 configuration in which two positive electrode active material layers 31 are stacked on both sides of one positive electrode current collector layer 32. However, the configuration of the positive electrode layer 3 is not limited to the above, and the positive electrode layer 3 may have a configuration in which one positive electrode active material layer 31 is stacked on one side of one positive electrode current collector layer 32.

[0059] The positive electrode active material layer 31 is not particularly limited and can be made of a material that can be used as a positive electrode active material for a solid-state battery. Examples of the positive electrode active material that makes up the positive electrode active material layer 31 include LiCoO2, LiNiO2, LiCo x Ni y Mn z O2 (x+y+z=1), LiVO2, LiCrO2, etc., layered positive electrode active material particles, LiMn2O4, Li(Ni 0.25 Mn 0.75 Examples of such positive electrode active materials include spinel-type positive electrode active materials such as LiCoPO, LiMnPO, and LiFePO; solid solution oxides (LiMnO-LiMO (M=Co, Ni, etc.)); conductive polymers such as polyaniline and polypyrrole; sulfides such as LiS, CuS, Li-Cu-S compounds, TiS, FeS, MoS, and Li-Mo-S compounds; and mixtures of sulfur and carbon. The positive electrode active material may be one of the above materials, or may be composed of two or more of the above materials.

[0060] An insulating frame 6 may be provided around the outer periphery of the positive electrode active material layer 31. The insulating frame 6 can prevent short circuits in the solid state battery 1 and improve its strength. In this embodiment, the insulating frame 6 is disposed so as to cover the side surfaces of the two positive electrode active material layers 31 formed on both sides of the positive electrode current collector layer 32. The insulating frame 6 also abuts against a portion of the stacking surface of the positive electrode current collector layer 32, and has a gap through which a positive electrode current collector tab 32a (described later) extends. The material for the insulating frame 6 is not particularly limited, but examples thereof include insulating oxides such as alumina, resins such as polyvinylidene fluoride (PVDF), and rubbers such as styrene-butadiene rubber (SBR).

[0061] The positive electrode current collector layer 32 is not particularly limited, and can be made of, for example, aluminum, stainless steel, conductive carbon (graphite, carbon nanotubes, etc.), etc. Examples of the shape of the positive electrode current collector layer 32 include foil, plate, mesh, nonwoven fabric, and foam. A portion of the positive electrode current collector layer 32 extends in a predetermined direction to form a positive electrode current collector tab 32a.

[0062] [Solid-state battery manufacturing method] 2A to 2F, the method for manufacturing a solid-state battery according to this embodiment is a method for manufacturing a solid-state battery having an electrode laminate La in which an anode layer 2, intermediate layers (a first intermediate layer 51 and a second intermediate layer 52), a solid electrolyte layer 4, and a cathode layer 3 are laminated in this order.

[0063] The method for manufacturing a solid-state battery according to this embodiment essentially includes the following steps: a first step of press-bonding the anode layer 2 and the first intermediate layer 51 to obtain a first intermediate layer-anode layer laminate L1; a second step of press-bonding the first intermediate layer-anode layer laminate L1 and the second intermediate layer 52 to obtain an intermediate layer-anode layer laminate L2; and a third step of arranging a material constituting a solid electrolyte layer (first solid electrolyte layer 41) on the lamination surface of the intermediate layer (second intermediate layer 52) in the intermediate layer-anode layer laminate L2 and press-bonding them to obtain a solid electrolyte layer-intermediate layer-anode layer laminate L3. The pressing temperature in each pressing step can be room temperature (approximately 25°C).

[0064] As shown in FIG. 2B , the first step is a step of placing a first intermediate layer 51 on the surface of the negative electrode layer 2 facing the negative electrode active material layer 21 and performing press bonding. Specific examples of a method for placing the first intermediate layer 51 on the surface facing the negative electrode active material layer 21 include a method of transferring the first intermediate layer 51 using an intermediate layer transfer sheet. The intermediate layer transfer sheet can be obtained, for example, by dispersing the material constituting the first intermediate layer 51 in a solvent, applying the resulting slurry to a support sheet, and drying the resulting slurry.

[0065] The pressure for pressing the negative electrode layer 2 and the first intermediate layer 51 together in the first step is not particularly limited as long as the pressure does not excessively deform the negative electrode layer 2 and the intermediate layer 5 and allows them to be bonded together without peeling in a subsequent step. The pressing pressure in the first step is, for example, in the range of 300 MPa or higher.

[0066] 2C, the second step is a step of placing a second intermediate layer 52 on the surface of the first intermediate layer-negative electrode layer laminate L1 on the side of the first intermediate layer 51, and performing press bonding. The second intermediate layer 52 may be a layer formed in advance in a sheet shape.

[0067] The pressure used to press the first intermediate layer-negative electrode layer laminate L1 and the second intermediate layer 52 in the second step is, for example, in the range of 300 MPa or more and 600 MPa or less.

[0068] As shown in FIG. 2A , the method for manufacturing a solid-state battery according to this embodiment preferably includes a step 1A of pressing the second intermediate layer 52 before the second step. By previously pressing and densifying the second intermediate layer 52 in the step 1A, the porosity of the second intermediate layer 52 can be set within a preferred range, and dendrite formation can be suppressed. For example, as shown in FIG. 2A , the step 1A can be performed by pressing the second intermediate layer 52 formed on the support sheet S. The second intermediate layer 52 may be peeled from the support sheet S after the step 1A, or the support sheet S may be peeled from the laminate obtained after the second step. The timing of the step 1A is not particularly limited as long as it is performed before the second step.

[0069] The pressure used to press the second intermediate layer 52 in step 1A is preferably higher than the pressure used in steps 1 and 2. This allows the second intermediate layer 52 to have a high density. The pressing pressure in step 1A is, for example, within a range of 600 MPa or higher and 1200 MPa or lower. The temperature during pressing in step 1A is preferably above room temperature and below 100°C. Room temperature means, for example, 25°C. By using the above pressing temperature, the intermediate layer can be preferably densified.

[0070] As shown in FIG. 2D , the third step is a step of placing a solid electrolyte layer on the surface of the intermediate layer-negative electrode layer laminate L2 on the side of the second intermediate layer 52 and performing press bonding. While FIG. 2D illustrates the first solid electrolyte layer 41 of a three-layer solid electrolyte layer 4 as the solid electrolyte layer, the solid electrolyte layer may also be a single layer. When a three-layer solid electrolyte layer 4 is used, the solid electrolyte layer press-bonded in the third step is preferably the first solid electrolyte layer 41 (i.e., one of the three solid electrolyte layers). The method of placing the solid electrolyte layer may be a method using a solid electrolyte transfer sheet similar to the intermediate layer transfer sheet described above, or a method using a solid electrolyte sheet formed in advance into a sheet shape.

[0071] 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 pressure used in the first and second steps, thereby increasing the density of the solid electrolyte layer. The pressure used in the third step is, for example, in the range of 500 MPa or more and 800 MPa or less.

[0072] 2F, the method for manufacturing a solid state battery according to this embodiment preferably includes a fourth step of press-bonding a solid electrolyte layer-intermediate layer-negative electrode layer laminate L3 and a layer including at least a positive electrode layer 3 to obtain an electrode laminate La. In each drawing, the layer including at least the positive electrode layer 3 is a solid electrolyte layer-positive electrode layer laminate L4 in which the positive electrode layer 3 and a third solid electrolyte layer 43 are laminated, but the present invention is not limited to this configuration.

[0073] The fourth step is preferably a step of placing a second solid electrolyte layer 42 between the solid electrolyte layer-intermediate layer-anode layer laminate L3 and the solid electrolyte layer-cathode layer laminate L4 so as to face each solid electrolyte layer, and press-bonding them to obtain an electrode laminate La. The second solid electrolyte layer 42 may be, for example, a pre-formed sheet. In this embodiment, the solid electrolyte layer-cathode layer laminate L4 has a third solid electrolyte layer 43 on both sides. Therefore, two second solid electrolyte layers 42 are placed so as to face both sides of the solid electrolyte layer-cathode layer laminate L4, and each layer is further placed so as to be sandwiched between two solid electrolyte layer-intermediate layer-anode layer laminates L3. If the solid electrolyte layer-cathode layer laminate L4 has a third solid electrolyte layer 43 on only one side, one second solid electrolyte layer 42 can be placed so as to face the third solid electrolyte layer 43, and one solid electrolyte layer-intermediate layer-anode layer laminate L3 can be further placed.

[0074] Since the fourth step is a step of integrating the layers, it is preferable to apply a pressing pressure that does not excessively deform the layers. From the above viewpoint, it is preferable that the pressing pressure in the fourth step is higher than the pressing pressure 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, in the range of 500 MPa or more and 900 MPa or less.

[0075] As shown in FIG. 2E, the method for manufacturing a solid-state battery according to this embodiment preferably includes, before step 4, step 3A, in which a layer including the positive electrode layer 3 is pressed. For example, as shown in FIG. 2E, step 3A is a step in which a material constituting a third solid electrolyte layer 43 is placed on the stacking surface of the positive electrode layer 3 and press-bonded to obtain a solid electrolyte layer-positive electrode layer stack L4. This is not limited to the above, and step 3A may also be a step in which only the positive electrode layer 3 is pressed. In this embodiment, the positive electrode layer 3 has positive electrode active material layers 31 formed on both sides of the positive electrode current collector layer 32, and the third solid electrolyte layer 43 is disposed on both positive electrode active material layers 31. If the positive electrode layer 3 has positive electrode active material layers 31 formed on only one side of the positive electrode current collector layer 32, the third solid electrolyte layer 43 can be disposed on a single positive electrode active material layer 31. The method for disposing the third solid electrolyte layer 43 may be the same as that of step 3.

[0076] The pressure used to press the layer including the positive electrode layer 3 in step 3A is preferably higher than the pressure used in step 4 to integrate the layers. This allows for a higher density of the layer including the positive electrode layer 3. The pressure used in step 3A is, for example, in the range of 700 MPa to 1200 MPa.

[0077] In each of the above steps, the press bonding apparatus is not particularly limited, and a roll press apparatus or a flat plate press apparatus can be used. When press bonding is performed using a roll press apparatus, the conveying direction of the objects to be press bonded to the roll press apparatus may be the same direction or different directions. For example, the conveying direction of the objects to the roll press apparatus in steps 3 and 3A may be different from or perpendicular to the conveying direction of the objects to the roll press apparatus in step 4. This allows the layers with a low Young's modulus to extend in one direction, which stretches the solid electrolyte layer 4 and reduces the likelihood of defects occurring in the solid electrolyte layer 4.

[0078] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. The solid-state battery 1 may have a configuration that can be used in a solid-state battery, such as an exterior body, in addition to the electrode laminate shown in Figure 1. The method for manufacturing a solid-state battery may include any steps other than those described above. [Explanation of symbols]

[0079] 1 solid state battery 2. Negative electrode layer 3 Positive electrode layer 4 Solid electrolyte layer 41 First solid electrolyte layer 42 Second solid electrolyte layer 43 Third solid electrolyte layer 51 First Middle Class 52 Second Middle Class L1 First intermediate layer-negative electrode layer laminate L2 intermediate layer-negative electrode layer laminate L3 Solid electrolyte layer-intermediate layer-negative electrode layer laminate La electrode laminate

Claims

1. A method for manufacturing a solid-state battery having an electrode stack in which an anode layer, an intermediate layer, a solid electrolyte layer, and a cathode layer are stacked in this order, comprising: the intermediate layer includes a first intermediate layer and a second intermediate layer, a first step of press-bonding the negative electrode layer and the first intermediate layer to obtain a first intermediate layer-negative electrode layer laminate; a second step of press-bonding 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 a material constituting the solid electrolyte layer on a lamination surface of the intermediate layer in the intermediate layer-negative electrode layer laminate and press-bonding the material to obtain a solid electrolyte layer-intermediate layer-negative electrode layer laminate.

2. a first step A of pressing the second intermediate layer before the second step; The method for manufacturing a solid-state battery according to claim 1 , wherein the pressing pressure in the first A step is higher than the pressing pressures in the first step and the second step.

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

4. a fourth step of press-bonding the solid electrolyte layer-intermediate layer-negative electrode layer stack and a layer including at least the positive electrode layer to obtain an electrode stack; The method for manufacturing a solid-state battery according to claim 1 , wherein the pressing pressure in the fourth step is higher than the pressing pressures in the first step and the second step.

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

6. a 3A step of pressing a layer including the positive electrode layer before the 4th step, The method for manufacturing a solid-state battery according to claim 4 , wherein the pressing pressure in the third step is higher than the pressing pressure in the fourth step.

7. 5. The method for producing a solid state battery according to claim 4, wherein the fourth step is a step of disposing a second solid electrolyte layer between the solid electrolyte layer-intermediate layer-negative electrode layer stack as a first solid electrolyte layer and a layer including the positive electrode layer, and press-bonding them to obtain an electrode stack.

8. 8. The method for producing a solid state battery according to claim 7, wherein the fourth step is a step of press-joining the solid electrolyte layer-intermediate layer-anode layer stack as a first solid electrolyte layer and a solid electrolyte layer-cathode layer stack including the cathode layer and a third solid electrolyte layer to obtain an electrode stack.

9. 3. The method for manufacturing a solid state battery according to claim 1, wherein the layers are press-bonded together so that the porosity of the second intermediate layer is 40% to 45%.

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

11. 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, 3. The method for manufacturing a solid-state battery according to claim 1, wherein the pressing pressure in the third step is 500 MPa or more and 800 MPa or less.

12. 3. The method for producing a solid-state battery according to claim 2, wherein the pressing pressure in the first A step is 600 MPa or more and 1200 MPa or less.

13. The method for producing a solid-state 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-state battery according to claim 2 , wherein the temperature during pressing in the first A step is equal to or higher than room temperature and equal to or lower than 100° C.

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