Manufacturing method for all-solid battery

Abstract

To provide a manufacturing method for an all-solid battery, by which an all-solid battery with the improved cycle characteristic can be obtained.SOLUTION: A manufacturing method for an all-solid battery includes, in the following order, a step A of forming a solid electrolyte layer 20 on a release film 10, a step B of obtaining a first multilayer body by applying one of a positive electrode 30 and a negative electrode 40 on the solid electrolyte layer 20, a step C of separating the release film 10 from the solid electrolyte layer 20, and a step D of obtaining a second multilayer body by applying the other of the positive electrode 30 and the negative electrode 40 on a separation surface of the release film 10 in the solid electrolyte layer 20. A ratio SC / SH of an uneven surface area SC to a horizontal projection area SH of a surface α of the release film 10 where the solid electrolyte layer is formed that is measured by a laser microscope is more than 1.1 and less than 5.0.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] It is known that in a step of forming a solid electrolyte layer in a method for producing an all-solid-state battery, the solid electrolyte layer is formed on a release film.

[0003] Patent Document 1 discloses a mold sheet for producing all-solid-state batteries, which is a sheet used in producing all-solid-state batteries, and contains one or more resins selected from the group consisting of polyester-based resins, polyolefin-based resins, fluorine-based resins, and polystyrene-based resins, and has a mold surface for transferring concaves and convexes on at least one surface. Furthermore, Patent Document 1 states that "the present invention aims to provide a mold sheet for producing an all-solid-state battery, which has high adhesive strength at the lamination interface with other layers and can be used to simply produce sheet-shaped solid electrolyte layers, positive electrode current collector layers, negative electrode current collector layers, etc., and to provide a method for producing an all-solid-state battery using the same." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-034675 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention provides a method for producing an all-solid-state battery, which is capable of obtaining an all-solid-state battery having improved cycle characteristics. [Means for solving the problem]

[0006] According to the present invention, there is provided a method for producing an all-solid-state battery as described below.

[0007] 1. Step A of forming a solid electrolyte layer on a release film; A step B of providing one of a positive electrode and a negative electrode on the solid electrolyte layer to obtain a first laminate; A step C of peeling the release film from the solid electrolyte layer; A step D of obtaining a second laminate by applying the other of the positive electrode and the negative electrode onto the release surface of the release film of the solid electrolyte layer; in this order, The horizontal projection area S of the surface α of the release film on which the solid electrolyte layer is formed, as measured by a laser microscope H The surface area of ​​the uneven surface S C Ratio of S C / S H A method for producing an all-solid-state battery, wherein 2. The surface roughness R of the surface α of the release film measured in accordance with JIS B 0601:2013 a 2. The method for producing an all-solid-state battery according to 1., wherein the thickness is more than 0.0 μm and less than 2.0 μm. 3. The method for producing an all-solid-state battery according to 1. or 2., further comprising a step E of vacuum sealing the first laminate between the step B and the step C. 4. The method for producing an all-solid-state battery according to any one of 1. to 3., further comprising a step F of pressurizing the first laminate between the step B and the step C. 5. The method for producing an all-solid-state battery according to any one of 1. to 4., further comprising, after step D, step G of vacuum sealing the second laminate. 6. The method for producing an all-solid-state battery according to any one of 1. to 5., further comprising a step H of pressurizing the second laminate after the step D. 7. The method for producing an all-solid-state battery according to any one of 1. to 6., wherein the release film has a thickness of 10 μm or more and 200 μm or less. 8. The method for producing an all-solid-state battery according to any one of 1. to 7., wherein the release film comprises a base film, and the base film comprises one or more resins selected from the group consisting of polyester-based resins, polyolefin-based resins, fluorine-based resins, and polystyrene-based resins. 9. The method for producing an all-solid-state battery according to any one of 1. to 8., wherein the release film includes a release layer. 10. The method for producing an all-solid-state battery according to any one of 1. to 9., wherein the solid electrolyte layer contains one or more electrolytes selected from the group consisting of a sulfide solid electrolyte, an oxide solid electrolyte, and a polymer electrolyte. 11. The method for producing an all-solid-state battery according to any one of 1. to 10., wherein the solid electrolyte layer has a thickness of 20 μm or more and 200 μm or less. Effect of the Invention

[0008] According to the present invention, there is provided a method for producing an all-solid-state battery, which can provide an all-solid-state battery with improved cycle characteristics. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a release film 10 for illustrating a horizontal projection area SH and a concave-convex surface area SC of a surface α on which a solid electrolyte layer is formed in the release film 10 of the present embodiment. FIG. [Diagram 2] 1 is a top view of release film 10 for illustrating a method for calculating the ratio SC / SH of the concave-convex surface area SC to the horizontal projected area SH of surface α on which a solid electrolyte layer is formed in release film 10 of the present embodiment. FIG. [Diagram 3] 1 is a cross-sectional view showing an example of a solid electrolyte layer 20 formed on a release film 10 of the present embodiment. [Figure 4] 2 is a cross-sectional view showing an example of a first laminate 50 of the present embodiment. [Diagram 5] FIG. 1 is a cross-sectional view showing an example of an all-solid-state battery 100 of the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the present invention will be described based on an embodiment.

[0011] The method for producing an all-solid-state battery of this embodiment includes, in this order, a step A of forming a solid electrolyte layer on a release film, a step B of providing one of a positive electrode and a negative electrode on the solid electrolyte layer to obtain a first laminate, a step C of peeling the release film from the solid electrolyte layer, and a step D of providing the other of a positive electrode and a negative electrode on the peeled surface of the release film in the solid electrolyte layer to obtain a second laminate, and the horizontal projection area S of the surface α of the release film on which the solid electrolyte layer is formed, measured with a laser microscope, H The surface area of ​​the uneven surface S C Ratio of S C / S H is greater than 1.1 and less than 5.0.

[0012] As a result of the investigations by the present inventors, the horizontal projection area S of the surface α of the release film on which the solid electrolyte layer is formed, which is measured by a laser microscope, H The surface area of ​​the uneven surface S C Ratio of S C / S H It has been revealed that this affects the cycle characteristics of all-solid-state batteries. S C / S H The mechanism by which S affects the cycle characteristics of solid-state batteries is unclear. C / S H It is presumed that the contact area between the solid electrolyte layer and the electrode is in an appropriate range by being within the above range, which improves the cycle characteristics of the all-solid-state battery. C / S H It is presumed that the mechanism by which the release film is easily peeled off when the thickness is within the above range, thereby making it difficult for defects to occur in the solid electrolyte layer and improving the cycle characteristics of the all-solid-state battery.

[0013] Here, referring to FIG. 1, the horizontal projection area S of the surface α of the release film 10 on which the solid electrolyte layer is formed is H and the uneven surface area S CThe horizontal projection area S of the surface α of the release film 10 will be described. H The area S of the concave and convex surface of the surface α of the release film 10 is defined as the area when the surface α is projected onto the horizontal plane 12. C means the area obtained by measuring the surface α using a laser microscope.

[0014] Here, referring to FIG. 2, the horizontal projection area S of the surface α of the release film 10 on which the solid electrolyte layer is formed is H The surface area of ​​the uneven surface S C Ratio of S C / S H The calculation method will be described below. First, a center line b passing through the center O of the surface α of the release film 10 1 Select center line b 1 A line b is parallel to 2 and b 3 Select center line b 1 Center line b perpendicular to 4 Select center line b 4 A line b is parallel to 5 and b 6 Select the vertical distance d between each line. 1 ~d 4 is, for example, 10 mm or more and 60 mm or less. Next, center line b 1 and center line b 4 Square area a centered on the intersection of 1 Select center line b 1 and line b 5 Square area a centered on the intersection of 2 Select center line b 1 and line b 6 Square area a centered on the intersection of 3 Select line b 2 and center line b 4 Square area a centered on the intersection of 4 Select line b 2 and line b 5 Square area a centered on the intersection of 5 Select line b 2 and line b 6 Square area a centered on the intersection of 6Select line b 3 and center line b 4 Square area a centered on the intersection of 7 Select line b 3 and line b 5 Square area a centered on the intersection of 8 Select line b 3 and line b 6 Square area a centered on the intersection of 9 Select the square area a 1 ~a 9 The length of one side is, for example, 10 μm or more and 1000 μm or less. Next, square area a 1 ~a 9 The uneven surface of the square area a is measured using a laser microscope. 1 ~a 9 The area of ​​the uneven surface is obtained. Next, square area a 1 Find the horizontal projection area of ​​a square area a. 1 ~a 9 The square area a is calculated by squaring the length of each side of the square a 1 ~a 9 The horizontal projection area of ​​the surface of the substrate can be calculated as follows: Next, square area a 1 ~a 9 The square area a for the average horizontal projection area of 1 ~a 9 The ratio of the average surface area of ​​the square area a 1 ~a 9 Average surface area of ​​unevenness / square area a 1 ~a 9 The average value of the horizontal projection area of ​​the surface α of the release film 10 on which the solid electrolyte layer is formed is calculated. H The surface area of ​​the uneven surface S C Ratio of S C / S H Let us assume that.

[0015] As the laser microscope, for example, VK-8700 manufactured by Keyence Corporation can be used. The magnification during measurement is, for example, 200 times. For measuring the area of ​​the uneven surface with the laser microscope, software VK-Viewer, VK-Assembler, and VK-Analyzer manufactured by Keyence Corporation can be used.

[0016] <Release film> The release film of the present embodiment will be described below.

[0017] The horizontal projection area S of the surface α of the release film on which the solid electrolyte layer is formed H The surface area of ​​the uneven surface S C Ratio of S C / S H From the viewpoint of further improving the cycle characteristics of the all-solid-state battery, is preferably more than 1.2, more preferably more than 1.3, even more preferably more than 1.5, even more preferably more than 1.7, even more preferably more than 1.9, and even more preferably more than 2.0, and is preferably less than 4.5, more preferably less than 4.0, even more preferably less than 3.8, even more preferably less than 3.6, even more preferably less than 3.4, even more preferably less than 3.2, even more preferably less than 3.0, even more preferably less than 2.8, and even more preferably less than 2.7.

[0018] Surface roughness R of release film surface α measured in accordance with JIS B 0601:2013 a From the viewpoint of further improving the cycle characteristics of the all-solid-state battery, is preferably more than 0.0 μm, more preferably more than 0.1 μm, even more preferably more than 0.3 μm, even more preferably more than 0.5 μm, even more preferably more than 0.7 μm, and is preferably less than 2.0 μm, more preferably less than 1.9 μm, even more preferably less than 1.7 μm, even more preferably less than 1.5 μm, and even more preferably less than 1.3 μm.

[0019] The thickness of the release film is preferably 10 μm or more, more preferably 20 μm or more, even more preferably 25 μm or more, and even more preferably 30 μm or more from the viewpoint of improving the strength of the film, and is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less from the viewpoint of improving the flexibility of the film.

[0020] The release film includes a base film, and from the viewpoint of improving the balance between strength and flexibility of the film, the base film preferably includes one or more resins selected from the group consisting of polyester-based resins, polyolefin-based resins, fluorine-based resins, and polystyrene-based resins, and more preferably includes a polyester-based resin.

[0021] The polyester-based resin includes, for example, one or more selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polycyclohexyldimethylene terephthalate, and polynaphthalene terephthalate.

[0022] The polyolefin resin includes, for example, one or more selected from the group consisting of ethylene homopolymers such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and high-pressure low-density polyethylene; propylene homopolymers (polypropylene); 1-butene homopolymers; 4-methyl-1-pentene homopolymers; 3-methyl-1-pentene homopolymers; ethylene / α-olefin copolymers; propylene / α-olefin copolymers; 1-butene / α-olefin copolymers, and 4-methyl-1-pentene / α-olefin copolymers.

[0023] The fluororesin includes, for example, one or more selected from the group consisting of polytetrafluoroethylene, polyvinylidene fluoride, polychlorotrifluoroethylene, polyvinyl fluoride, a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene, a copolymer of tetrafluoroethylene and hexafluoropropylene, a copolymer of tetrafluoroethylene and ethylene, a copolymer of chlorotrifluoroethylene and ethylene, and a ternary copolymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride.

[0024] The thickness of the base film is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more from the viewpoint of improving the strength of the film, and is preferably 100 μm or less, more preferably 80 μm or less, even more preferably 70 μm or less, and even more preferably 60 μm or less from the viewpoint of improving the flexibility of the film.

[0025] The release film preferably includes a release layer from the viewpoint of facilitating peeling of the film. The release layer includes, for example, one or more types selected from the group consisting of silicone-based resins and fluorine-based resins.

[0026] Furthermore, the thickness of the release layer is not particularly limited, but may be, for example, 0.1 μm or more, 0.3 μm or more, and 5 μm or less, 3 μm or less, or 2 μm or less.

[0027] The release film may have a single-layer structure formed from one layer, or may have a laminated structure formed from a plurality of layers.

[0028] Hereinafter, each step of the method for producing the all-solid-state battery of this embodiment will be described.

[0029] <Process A> The method for producing an all-solid-state battery of this embodiment includes a step A of forming a solid electrolyte layer 20 on a release film 10. Hereinafter, the step A will be described.

[0030] FIG. 3 shows a state in which a solid electrolyte layer 20 is formed on a release film 10.

[0031] The method for forming the solid electrolyte layer on the release film in step A is not particularly limited. For example, a slurry containing a solid electrolyte may be applied onto the release film 10 and dried to form the solid electrolyte layer 20. The coating method is not particularly limited, and for example, the coating can be performed by a doctor blade method, a die coater method, a comma coater method, a screen printing method, or the like.

[0032] The solid electrolyte layer contains, for example, one or more selected from the group consisting of a sulfide solid electrolyte, an oxide solid electrolyte, and a polymer electrolyte, and preferably contains a sulfide solid electrolyte.

[0033] The sulfide solid electrolyte is, for example, Li 7 P 3 S 11 , Li 3 P.S. 4 , Li 8 P 2 S 9 , Li 2 S-SiS 2 , LiI-Li 2 S-SiS 2 , LiI-Li 2 SP 2 S 5 , LiI-LiBr-Li 2 SP 2 S 5 , Li 13 GeP 3 S 16 , Li 10 GeP 2 S 12 , LiI-Li 2 SP 2 O 5 , LiI-Li 3 PO 4 -P 2 S 5 and Li 7-x P.S. 6-x Cl xPreferably, the compound contains one or more selected from the group consisting of Li 7-x P.S. 6-x Cl x Includes.

[0034] The oxide solid electrolyte is, for example, Li 7 La 3 Zr 2 O 12 , Li 7-x La 3 Zr 1-x Nb x O 12 , Li 7-3x La 3 Zr 2 Al x O 12 , Li 3x La 2 / 3-x TiO 3 , Li 1+x Al x Ti 2-x (PO 4 ) 3 , Li 1+x Al x Ge 2-x (PO 4 ) 3 , Li 3 PO 4 and Li 3+x PO 4-x N x Preferably, the compound contains one or more selected from the group consisting of Li 7-3x La 3 Zr 2 Al x O 12 Includes.

[0035] The polymer electrolyte includes, for example, one or more selected from the group consisting of polyethylene oxide and polypropylene oxide, and preferably includes polyethylene oxide.

[0036] The thickness of the solid electrolyte layer is preferably 20 μm or more, more preferably 25 μm or more, and even more preferably 30 μm or more, from the viewpoint of suppressing defects such as cracks, and is preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less, from the viewpoint of making the all-solid-state battery thinner.

[0037] The solid electrolyte layer may have a single-layer structure formed from one layer, or may have a laminated structure formed from a plurality of layers.

[0038] <Process B> The method for manufacturing the all-solid-state battery 100 of this embodiment includes a step B of obtaining a first laminate 50 by providing one of the positive electrode 30 and the negative electrode 40 on the solid electrolyte layer 20. Hereinafter, the step B will be described.

[0039] 4 shows an example of a first laminate 50 in which a solid electrolyte layer 20 is formed on a release film 10, and a positive electrode 30 is further provided thereon. That is, FIG. 4 shows the state before the release film 10 is peeled off.

[0040] The positive electrode 30 includes, for example, a positive electrode current collector 32 and a positive electrode active material layer 34. Although an example in which the positive electrode active material layer 34 is provided on one side of the positive electrode current collector 32 is disclosed in Figures 4 and 5, the positive electrode active material layer 34 may be provided on both sides of the positive electrode current collector 32.

[0041] The positive electrode current collector 32 includes, for example, one or more materials selected from the group consisting of aluminum, stainless steel, nickel, titanium, and alloys thereof.

[0042] The thickness of the positive electrode current collector 32 is, for example, not less than 1 μm and not more than 50 μm.

[0043] The positive electrode active material layer 34 includes, for example, a positive electrode active material, a binder resin, and a conductive assistant.

[0044] The positive electrode active material is not particularly limited, and examples thereof include composite oxides of lithium and transition metals such as lithium-nickel composite oxide, lithium-cobalt composite oxide, lithium-manganese composite oxide, lithium-nickel-manganese composite oxide, lithium-nickel-cobalt composite oxide, lithium-nickel-aluminum composite oxide, lithium-nickel-cobalt-aluminum composite oxide, lithium-nickel-manganese-cobalt composite oxide, lithium-nickel-manganese-aluminum composite oxide, and lithium-nickel-cobalt-manganese-aluminum composite oxide; TiS 2 , FeS, MoS 2 Transition metal sulfides such as MnO, V 2 O 5 , V 6 O 13 , TiO 2 and olivine-type lithium phosphate, and from the viewpoint of improving the working potential, capacity, durability, and energy density, preferably, the lithium iron phosphate oxide includes one or more selected from the group consisting of olivine-type lithium iron phosphate, lithium-nickel composite oxide, lithium-cobalt composite oxide, lithium-manganese composite oxide, lithium-nickel-manganese composite oxide, lithium-nickel-cobalt composite oxide, lithium-nickel-aluminum composite oxide, lithium-nickel-cobalt-aluminum composite oxide, lithium-nickel-manganese-cobalt composite oxide, lithium-nickel-manganese-aluminum composite oxide, and lithium-nickel-cobalt-manganese-aluminum composite oxide. Here, the olivine-type lithium phosphate contains, for example, at least one element selected from the group consisting of Mn, Cr, Co, Cu, Ni, V, Mo, Ti, Zn, Al, Ga, Mg, B, Nb, and Fe, as well as lithium, phosphorus, and oxygen.

[0045] The positive electrode active material layer 34 contains, for example, 90 parts by mass or more and 99 parts by mass or less of the positive electrode active material with respect to 100 parts by mass of the total mass of the positive electrode active material layer 34.

[0046] The binder resin contained in the positive electrode active material layer 34 includes, for example, one or more types selected from the group consisting of polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF).

[0047] The positive electrode active material layer 34 contains, for example, 0.1 parts by mass or more and 10.0 parts by mass or less of a binder resin with respect to 100 parts by mass of the total mass of the positive electrode active material layer 34.

[0048] The conductive assistant contained in the positive electrode active material layer 34 includes, for example, one or more selected from the group consisting of carbon black, ketjen black, acetylene black, natural graphite, artificial graphite, and carbon fibers such as carbon nanotubes. The graphite may be, for example, flake graphite or spherical graphite.

[0049] The positive electrode active material layer 34 contains, for example, 0.01 parts by mass or more and 8.0 parts by mass or less of a conductive assistant with respect to 100 parts by mass of the total mass of the positive electrode active material layer 34.

[0050] The negative electrode 40 includes, for example, a negative electrode current collector 42 and a negative electrode active material layer 44. Although an example in which the negative electrode active material layer 44 is provided on one side of the negative electrode current collector 42 is disclosed in Fig. 5, the negative electrode active material layer 44 may be provided on both sides of the negative electrode current collector 42.

[0051] The negative electrode current collector 42 includes, for example, one or more materials selected from the group consisting of copper, stainless steel, nickel, titanium, and alloys thereof.

[0052] The negative electrode current collector 42 has a thickness of, for example, not less than 1 μm and not more than 50 μm.

[0053] The negative electrode active material layer 44 includes, for example, a negative electrode active material, a binder resin, and a conductive assistant.

[0054] The negative electrode active material is not particularly limited, and examples thereof include carbon materials such as graphite, amorphous carbon, diamond-like carbon, fullerene, carbon nanotubes, and carbon nanohorns; lithium-based metal materials such as lithium metal and lithium alloys; Si, SiO2 It contains one or more selected from the group consisting of Si-based materials such as SiOx (0 < x ≤ 2) and Si-containing composite materials, and conductive polymer materials such as polyacene, polyacetylene, and polypyrrole.

[0055] The negative electrode active material layer 44 contains, for example, 90 parts by mass or more and 99 parts by mass or less of a negative electrode active material with respect to 100 parts by mass of the total mass of the negative electrode active material layer 44.

[0056] The binder resin contained in the negative electrode active material layer 44 contains, for example, one or more selected from the group consisting of rubber-based binders (for example, SBR (styrene-butadiene rubber)) and acrylic-based binders. Further, the binder may contain a thickener such as CMC (carboxymethyl cellulose).

[0057] The negative electrode active material layer 44 contains, for example, 0.1 part by mass or more and 10.0 parts by mass or less of a binder resin with respect to 100 parts by mass of the total mass of the negative electrode active material layer 44.

[0058] The conductive assistant contained in the negative electrode active material layer 44 contains, for example, one or more selected from the group consisting of carbon fibers such as carbon black, ketjen black, acetylene black, natural graphite, artificial graphite, and carbon nanotubes. The graphite may be, for example, flaky graphite or spherical graphite.

[0059] The negative electrode active material layer 44 contains, for example, 0.01 part by mass or more and 8.0 parts by mass or less of a conductive assistant with respect to 100 parts by mass of the total mass of the negative electrode active material layer 44.

[0060] <Process C> The manufacturing method of the all-solid-state battery of the present embodiment includes Process C of peeling the release film from the solid electrolyte layer.

[0061] The manufacturing method of the all-solid-state battery of the present embodiment preferably includes Process C of peeling the release film from the solid electrolyte layer after Process B of obtaining the first laminate by applying one of the positive electrode 30 and the negative electrode 40 on the solid electrolyte layer 20.

[0062] <Process E> The method for producing an all-solid-state battery of this embodiment preferably further includes a step E of vacuum sealing the first laminate between steps B and C. This makes it possible to remove moisture, oxygen, etc., and suppress deterioration of the all-solid-state battery. This also makes it possible to closely adhere each layer of the all-solid-state battery.

[0063] <Process F> The method for producing an all-solid-state battery of this embodiment preferably further includes a step F of pressurizing the first laminate between step B and step C. This allows the layers of the all-solid-state battery to be tightly attached to each other.

[0064] In step F, heating may be carried out in addition to the application of pressure.

[0065] The method for producing an all-solid-state battery of this embodiment preferably includes both step E and step F, and more preferably includes step F after step E.

[0066] <Process D> The method for producing an all-solid-state battery of this embodiment includes a step D of providing the other of the positive electrode and the negative electrode on the release surface of the release film in the solid electrolyte layer to obtain a second laminate.

[0067] <Process G> The method for producing the all-solid-state battery of this embodiment preferably further includes a step G of vacuum sealing the second laminate after the step D of providing the other of the positive electrode and the negative electrode on the release surface of the release film in the solid electrolyte layer to obtain a second laminate. This makes it possible to remove moisture, oxygen, etc., and to suppress deterioration of the all-solid-state battery. This also makes it possible to closely adhere each layer of the all-solid-state battery.

[0068] <Process H> The method for producing the all-solid-state battery of this embodiment preferably further includes a step H of pressurizing the second laminate after a step D of providing the other of the positive electrode and the negative electrode on the release surface of the release film in the solid electrolyte layer to obtain a second laminate, thereby allowing each layer of the all-solid-state battery to adhere closely to each other.

[0069] In step H, heating may be carried out in addition to the application of pressure.

[0070] The method for producing an all-solid-state battery of this embodiment preferably includes both step G and step H, and more preferably includes step H after step G.

[0071] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can be adopted. Furthermore, the present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of the present invention are included in the present invention. EXAMPLES

[0072] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0073] <Release film> The release films used in the examples and comparative examples are as follows. Comparative Example 1 Release film a manufactured by company A (material of base film: polyester resin, thickness of base film: 40 μm, material of release layer: silicone resin, thickness of release layer: 0.5 μm) Example 1 Release film b manufactured by Company B (material of base film: polyester resin, thickness of base film: 50 μm, material of release layer: silicone resin, thickness of release layer: 1 μm) Example 2 Release film c manufactured by company C (material of base film: polyester resin, thickness of base film: 50 μm, material of release layer: silicone resin, thickness of release layer: 1 μm) Example 3 Release film d manufactured by Company D (material of base film: polyester resin, thickness of base film: 50 μm, material of release layer: silicone resin, thickness of release layer: 1.5 μm)

[0074] The horizontal projection area S of the surface α of the release film on which the solid electrolyte layer is formed is measured by the following method. H The surface area of ​​the uneven surface S C Ratio of S C / S H was calculated. First, the center line b passing through the center O of the surface α of the release film 1 Select center line b 1 A line b is parallel to 2 and b 3 Select center line b 1 Center line b perpendicular to 4 Select center line b 4 A line b is parallel to 5 and b 6 The vertical distance between each line is d 1 ~d 4 was 50mm. Next, center line b 1 and center line b 4 Square area a centered on the intersection of 1 Select center line b 1 and line b 5 Square area a centered on the intersection of 2 Select center line b 1 and line b 6 Square area a centered on the intersection of 3 Select line b 2 and center line b 4 Square area a centered on the intersection of 4 Select line b 2 and line b 5 Square area a centered on the intersection of 5 Select line b 2 and line b 6 Square area a centered on the intersection of 6 Select line b 3 and center line b 4 Square area a centered on the intersection of 7 Select line b3 and line b 5 Square area a centered on the intersection of 8 Select line b 3 and line b 6 Square area a centered on the intersection of 9 The square area a 1 ~a 9 The length of each side was 300 μm. Next, square area a 1 ~a 9 The uneven surface of the square area a was measured using a laser microscope VK-8700 manufactured by Keyence Corporation, set at a magnification of 50 times, and analyzed using software VK-Assembler and VK-Analyzer manufactured by Keyence Corporation. 1 ~a 9 The rough surface area was obtained. Next, square area a 1 ~a 9 The square area a is calculated by squaring the length of each side of the square a 1 ~a 9 The horizontal projection area was calculated as: Next, square area a 1 ~a 9 The square area a for the average horizontal projection area of 1 ~a 9 The ratio of the average surface area of ​​the square area a 1 ~a 9 Average surface area of ​​unevenness / square area a 1 ~a 9 The average value of the horizontal projection area of ​​the surface α of the release film 10 on which the solid electrolyte layer is formed is calculated. H The surface area of ​​the uneven surface S C Ratio of S C / S H It was decided. The results are shown in Table 1.

[0075] The surface roughness R of surface α measured in accordance with JIS B 0601:2013 a , and square area a 1 ~a 9 The area of ​​the uneven surface S C The details of the measurement method are as follows. First, the release film was observed in the following manner. (1) I launched Keyence's VK-Viewer software and selected "Expert Mode." (2) The XY stage of the laser microscope was lowered. (3) Select "Z origin" and move the objective lens to the Z origin. (4) "Beginner Mode" was selected. (5) The rotation stage of the laser microscope was removed, and a release film was fixed to the rotation stage with the surface α on which the solid electrolyte layer was to be formed facing up, and the rotation stage was returned to its original position. (6) The lens was switched so that the measurement magnification was 50x, and the measurement position and focus were adjusted. (7) The measurement range in the height direction of the release film was set. (8) The brightness of the laser was adjusted, measurements were taken, and image data was obtained. Next, the obtained image data was linked by the following procedure. (10) Launched Keyence software VK-Assembler. (11) Select and open all the images to be linked. (12) Adjusted the image positions and concatenated all selected images. The concatenated images were then analyzed using the following procedure. (13) Launched Keyence's software VK-Analyzer. (14) The linked image data was subjected to pre-measurement processing. (15) The analytical method was selected and the analysis was performed.

[0076] That is, the surface α of the release film on which the solid electrolyte layer is to be formed was measured using a laser microscope VK-8700 manufactured by Keyence Corporation, set at a magnification of 50 times, and analyzed using software VK-Viewer, VK-Assembler, and VK-Analyzer manufactured by Keyence Corporation. The surface roughness R a and S C / S H obtained. The results are shown in Table 1.

[0077] An all-solid-state battery was manufactured by the following method. (1) A negative electrode active material (Li metal foil) was placed on a negative electrode current collector (stainless steel foil) to form a negative electrode. (2) Apply a solid electrolyte material (Li 7-x P.S. 6-x Cl x A slurry containing 1,2-dichlorophenyl ether was applied onto the substrate and dried to form a solid electrolyte layer. (3) The negative electrode and the solid electrolyte layer were laminated to obtain a laminate (I). (4) The release film was peeled off from the laminate (I). (5) A slurry containing a positive electrode active material (lithium-nickel-manganese composite oxide) was applied onto a positive electrode current collector (aluminum foil) and dried to form a positive electrode. (6) A positive electrode was laminated on the surface of the solid electrolyte layer of the laminate (I) from which the release film had been peeled off, to obtain a laminate (II). (7) Tabs were attached to both ends of the laminate (II) and then the laminate was sealed to obtain an all-solid-state battery.

[0078] <Cycle characteristics> The cycle characteristics of the all-solid-state battery were evaluated by repeatedly charging and discharging the all-solid-state battery obtained by the above method under the following charging and discharging conditions. Charging: constant current-constant voltage method, rate = 1 / 20C Discharge: constant current, rate = 1 / 20C Note that "C" is the symbol for the current rate (time rate). A rate of 1C will fully discharge the rated capacity of the battery in 1 hour. In the above cycle test, the ratio of the discharge capacity after the second charge / discharge to the initial discharge capacity is called the capacity retention rate. The battery was repeatedly charged and discharged under the above charge and discharge conditions, and the capacity retention rate after 100 charge and discharge tests, i.e., the 100th cycle, was determined and taken as the "cycle characteristics (@100 cycles)." The results are shown in Table 1.

[0079] [Table 1]

[0080] According to the manufacturing method of the all-solid-state battery of the Example, an all-solid-state battery having improved cycle characteristics was obtained compared to the Comparative Example. From this, it is understood that according to the manufacturing method of the all-solid-state battery of the present embodiment, an all-solid-state battery having improved cycle characteristics can be obtained. [Explanation of symbols]

[0081] 10 Release film 12 horizontal plane 20 Solid electrolyte layer 30 positive electrode 32 Positive electrode current collector 34 Cathode active material layer 40 negative electrode 42 Negative electrode current collector 44 Negative electrode active material layer 50 First laminate 100 solid state battery a 1 ~a 9 square area b 1 and b 4 center line b 2 ~b 3 and b 5 ~b 6 straight line d 1 ~d 6 The vertical distance between each line O center α Surface on which the solid electrolyte layer is formed α

Claims

1. A step A of forming a solid electrolyte layer on a release film; A step B of providing one of a positive electrode and a negative electrode on the solid electrolyte layer to obtain a first laminate; A step C of peeling the release film from the solid electrolyte layer; a step D of providing the other of the positive electrode and the negative electrode on the release surface of the release film of the solid electrolyte layer to obtain a second laminate; in this order, The horizontal projection area S of the surface α of the release film on which the solid electrolyte layer is formed, as measured by a laser microscope Ｈ The surface area S of the uneven surface Ｃ The ratio S Ｃ / S Ｈ A method for producing an all-solid-state battery,

2. The surface roughness R of the surface α of the release film measured in accordance with JIS B 0601:2013 ａ The method for producing an all-solid-state battery according to claim 1 , wherein the thickness is more than 0.0 μm and less than 2.0 μm.

3. The method for producing an all-solid-state battery according to claim 1 or 2, further comprising a step E of vacuum sealing the first laminate between the step B and the step C.

4. The method for producing an all-solid-state battery according to any one of claims 1 to 3, further comprising a step F of pressurizing the first laminate between the step B and the step C.

5. The method for producing an all-solid-state battery according to any one of claims 1 to 4, further comprising a step G of vacuum sealing the second laminate after the step D.

6. The method for producing an all-solid-state battery according to any one of claims 1 to 5, further comprising a step H of pressurizing the second stack after the step D.

7. The method for producing an all-solid-state battery according to any one of claims 1 to 6, wherein the release film has a thickness of 10 µm or more and 200 µm or less.

8. The method for producing an all-solid-state battery according to any one of claims 1 to 7, wherein the release film comprises a substrate film, and the substrate film comprises one or more resins selected from the group consisting of polyester-based resins, polyolefin-based resins, fluorine-based resins, and polystyrene-based resins.

9. The method for producing an all-solid-state battery according to any one of claims 1 to 8, wherein the release film includes a release layer.

10. The method for producing an all-solid-state battery according to any one of claims 1 to 9, wherein the solid electrolyte layer contains one or more electrolytes selected from the group consisting of a sulfide solid electrolyte, an oxide solid electrolyte, and a polymer electrolyte.

11. The method for producing an all-solid-state battery according to any one of claims 1 to 10, wherein the thickness of the solid electrolyte layer is 20 µm or more and 200 µm or less.

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