Current collector and battery

Abstract

To provide a current collector and a battery with improved adhesion.SOLUTION: The current collector 1 has a metal layer 2 and a resin layer 3 formed on the metal layer 2, and the resin layer 3 contains a silane coupling agent. The battery 10 includes a positive electrode CA, a negative electrode AN including a current collector 1 and a negative electrode active material layer 4, and a solid electrolyte layer EL disposed between the positive electrode CA and the negative electrode AN, wherein the current collector 1 includes a metal layer 2 and a resin layer 3 formed on the metal layer 2, and the resin layer 3 contains a silane coupling agent and faces the negative electrode active material layer 4.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a current collector and a battery. [Background technology]

[0002] In recent years, with the rapid spread of electronic devices such as personal computers and mobile phones, The development of batteries that can be used in hybrid vehicles (HE) is also progressing in the automobile industry. V), plug-in hybrid vehicles (PHEV) or battery electric vehicles (BEV) Battery development is underway.

[0003] For example, Patent Document 1 discloses a battery having a laminated current collector in which multiple current collectors are stacked, and describes that the current collector used in this battery has a resin layer and a metal layer coated on the resin layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-97018 Summary of the Invention [Problem to be solved by the invention]

[0005] Known batteries using a solid electrolyte include all-solid-state batteries having a positive electrode, a negative electrode, and a solid electrolyte layer laminated between the positive and negative electrodes. The manufacturing process for such all-solid-state batteries may include a transfer step in which the solid electrolyte layer is transferred to a negative electrode active material layer formed on a negative electrode current collector. In the transfer step, the solid electrolyte layer is transferred by pressing a laminate including the negative electrode current collector, the negative electrode active material layer, and the solid electrolyte layer. However, when the current collector described in Patent Document 1 is used as the negative electrode current collector, there is a problem in that the negative electrode active material layer is easily peeled off from the current collector due to the low adhesion between the resin layer of the current collector and the negative electrode active material layer when pressed under high pressure during transfer.

[0006] The present disclosure has been made to solve such problems, and aims to provide a current collector and a battery with improved adhesion. [Means for solving the problem]

[0007] A current collector according to one embodiment has a metal layer and a resin layer formed on the metal layer, and the resin layer contains a silane coupling agent.

[0008] A battery according to one embodiment includes a positive electrode, a negative electrode including a current collector and a negative electrode active material layer, and a solid electrolyte layer disposed between the positive electrode and the negative electrode. The current collector includes a metal layer and a resin layer formed on the metal layer. The resin layer contains a silane coupling agent and faces the negative electrode active material layer. [Effects of the Invention]

[0009] The present disclosure makes it possible to provide a current collector and a battery with improved adhesion. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view showing a current collector according to a first embodiment. [Figure 2] 1 is a schematic cross-sectional view showing a battery according to a first embodiment. [Figure 3] 3 is a flowchart showing a method for manufacturing a battery according to the first embodiment. [Figure 4] 1 is a schematic cross-sectional view illustrating a method for manufacturing a battery according to a first embodiment. [Figure 5] 4A and 4B are diagrams illustrating bonding between a negative electrode active material layer and a current collector. [Figure 6] 1 is a graph showing the results of a peel test. DETAILED DESCRIPTION OF THE INVENTION

[0011] Embodiment 1 Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, the present disclosure is not limited to the following embodiments. In addition, the following description and drawings have been simplified as appropriate for clarity of explanation.

[0012] 1. Current collector FIG. 1 is a schematic cross-sectional view showing a current collector according to the first embodiment. As shown in FIG. 1, the current collector 1 according to the first embodiment has a metal layer 2 and a resin layer 3 formed on the metal layer 2. The resin layer 3 contains a silane coupling agent. By including the silane coupling agent in the resin layer 3, a chemical bonding action by the silane coupling agent is obtained. Therefore, when the current collector 1 is placed opposite an inorganic material layer containing an inorganic material so that the resin layer 3 is in contact with the inorganic material layer, the adhesion between the inorganic material layer and the current collector 1 can be improved.

[0013] Examples of metals contained in the metal layer 2 include stainless steel (SUS), gold, platinum, zinc, nickel, tin, aluminum, molybdenum, niobium, tantalum, tungsten, and titanium. The metal layer 2 may be in the form of, for example, a foil or a mesh. For example, a metal foil may be used as the metal layer 2. The thickness of the metal layer 2 is, for example, from 1 μm to 50 μm, and preferably from 5 μm to 30 μm.

[0014] Examples of the resin contained in the resin layer 3 include thermoplastic resins, thermosetting resins, and conductive polymers. The type of resin can be appropriately selected depending on the application of the current collector 1.

[0015] Examples of thermoplastic resins include poly(meth)acrylic acid, polymethyl(meth)acrylate, polyethylene, polypropylene, polyethylene terephthalate, polyether nitrile, polyimide, polyamide, polytetrafluoroethylene, polyacrylonitrile, poly(meth)acrylate, and vinyl halide resin. Note that "(meth)acrylic acid" is a concept that encompasses both acrylic acid and methacrylic acid, and "(meth)acrylate" is a concept that encompasses both acrylate and methacrylate.

[0016] In particular, it is preferable that the resin layer 3 contains a thermoplastic resin having a glass transition point of 140° C. or higher. This allows the formation of a resin layer 3 having heat resistance of 140° C. or higher, which is the temperature during heating performed in the battery manufacturing process. Examples of thermoplastic resins having a glass transition point of 140° C. or higher include polyamide, polyamideimide, polyimide, and polycarbonate.

[0017] Examples of thermosetting resins include epoxy resins and vinyl ester resins. The resin layer 3 usually contains a cured product of the thermosetting resin. Examples of conductive polymers include polyaniline and polypyrrole. The resin layer 3 may contain one type of resin or two or more types of resins.

[0018] The resin layer 3 may contain a conductive material. Examples of the conductive material include carbon materials. Examples of the carbon material include particulate carbon materials such as acetylene black (AB) and ketjen black (KB), and fibrous carbon materials such as carbon fiber, carbon nanotubes (CNT), and carbon nanofibers (CNF).

[0019] The thickness of the resin layer 3 is, for example, 0.5 μm to 20 μm, preferably 1 μm to 5 μm. The inclusion of a silane coupling agent improves the adhesion of the resin layer 3, allowing the thickness of the resin layer 3 to be thinner than when the silane coupling agent is not included. As a result, the weight of the battery using the current collector 1 can be reduced.

[0020] When the current collector 1 is used as a negative electrode current collector for a battery, a resin is selected that is insoluble in a solvent used to form a slurry of the negative electrode active material and has heat resistance sufficient to withstand the heating temperatures used in the battery manufacturing process. However, if the resin layer 3 is formed using only a resin that satisfies these conditions, there is a risk that the adhesion between the negative electrode active material layer 4 containing the negative electrode active material and the resin layer 3 of the current collector 1 will be reduced. Therefore, in the current collector 1 according to the first embodiment, the resin layer 3 contains a silane coupling agent.

[0021] A silane coupling agent is an organosilicon compound that has, in one molecule, an organic functional group that reacts with organic materials and a hydrolyzable group that reacts with inorganic materials.

[0022] Examples of silane coupling agents include vinyl-based silane coupling agents such as vinyltrimethoxysilane and vinyltriethoxysilane; epoxy-based silane coupling agents such as 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 3-glycidoxypropyltriethoxysilane; and styryl-based silane coupling agents such as p-styryltrimethoxysilane; Methacrylic silane coupling agents such as 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, and 3-methacryloxypropyltriethoxysilane; acrylic silane coupling agents such as 3-acryloxypropyltrimethoxysilane; N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, and 3-aminopropyltrimethoxysilane; amino-based silane coupling agents such as triethoxysilane, 3-aminopropyltriethoxysilane, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-8-aminooctyltrimethoxysilane, and N-(vinylbenzyl)-2-aminoethyl-3-aminopropyltrimethoxysilane; isocyanurate-based silane coupling agents such as tris-(trimethoxysilylpropyl)isocyanurate; 3-ureidopropyl Examples of such silane coupling agents include ureido-based silane coupling agents such as trialkoxysilane; mercapto-based silane coupling agents such as 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane; isocyanate-based silane coupling agents such as 3-isocyanatepropyltriethoxysilane; and acid anhydride-based silane coupling agents such as 3-trimethoxysilylpropylsuccinic anhydride, 3-triethoxysilylpropylsuccinic anhydride and 3-dimethylmethoxysilylpropylsuccinic anhydride. These can be used alone or in combination of two or more.

[0023] The type of silane coupling agent can be appropriately selected depending on the type of resin and the type of conductive material. For example, when polyimide is used as the resin contained in the resin layer 3, an acid anhydride silane coupling agent is preferred as the silane coupling agent from the viewpoint of high reactivity with polyimide. The acid anhydride silane coupling agent has an acid anhydride group as an organic functional group.

[0024] Among acid anhydride coupling agents, 3-trimethoxysilylpropylsuccinic anhydride is preferred because it does not chemically react with various conductive materials. 3-Trimethoxysilylpropylsuccinic anhydride has an acid anhydride group as an organic functional group and a methoxy group as a hydrolyzable group.

[0025] When the resin contained in the resin layer 3 is taken as 100 mass %, the blending amount of the silane coupling agent relative to the resin is preferably 0.5 mass % or more and 2.0 mass % or less. This makes it possible to obtain a current collector 1 with improved adhesion to the resin layer 3, and also makes it possible to suitably transfer a solid electrolyte layer when manufacturing a battery using the current collector 1.

[0026] The surface of the resin layer 3 that comes into contact with the inorganic material layer may be roughened to further enhance the adhesion of the current collector 1. However, by incorporating a silane coupling agent into the resin layer 3, it is possible to obtain a current collector 1 with sufficiently enhanced adhesion of the resin layer 3 even if the surface of the resin layer 3 is not roughened.

[0027] The resin layer 3 is formed, for example, by applying a slurry-like resin layer-forming composition, in which a resin and a silane coupling agent are dispersed in a solvent, to the metal layer 2 and then drying the composition. The resin layer-forming composition is used as a material for forming the resin layer 3. The resin layer-forming composition may contain additives such as a dispersant.

[0028] The solvent is not particularly limited as long as it can dissolve or disperse the resin and silane coupling agent contained in the resin layer-forming composition and does not substantially chemically react with each component. Examples of the solvent include organic solvents such as N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethylenetriamine, N,N-dimethylaminopropylamine, ethylene oxide, and tetrahydrofuran.

[0029] When the surface of the resin layer 3 is not roughened, the resin layer 3 can be easily formed by simply applying the resin layer-forming composition to the metal layer 2 and then drying it.

[0030] 2.Battery The current collector 1 described above can be used in a battery 10 shown in Fig. 2. Fig. 2 is a schematic cross-sectional view showing a battery according to the first embodiment. As shown in Fig. 2, the battery 10 according to the first embodiment has a positive electrode CA, a negative electrode AN, and a solid electrolyte layer EL disposed between the positive electrode CA and the negative electrode AN.

[0031] The battery 10 may have an exterior housing that houses a power generating element including a positive electrode CA, a negative electrode AN, and a solid electrolyte layer EL disposed between the positive electrode CA and the negative electrode AN. When the battery 10 has an exterior housing, the power generating element is sealed inside the exterior housing. Examples of the exterior housing include a laminate-type exterior housing and a case-type exterior housing.

[0032] The battery 10 also includes a positive electrode current collector attached by welding or the like to a positive electrode current collector 5 constituting the positive electrode CA, and a negative electrode current collector attached by welding or the like to a metal layer 2 of a current collector 1 constituting the negative electrode AN. The positive electrode current collector is preferably attached to a positive electrode tab portion of the positive electrode current collector 5 where the positive electrode active material layer 6 is not formed and the positive electrode current collector 5 is exposed. The negative electrode current collector is preferably attached to a negative electrode tab portion of the current collector 1 where the resin layer 3 is not formed and the metal layer 2 is exposed.

[0033] The battery 10 may have a restraining jig that applies a restraining pressure to the power generating element in the thickness direction of the power generating element. The restraining jig applies a restraining pressure to the power generating element in the thickness direction, thereby maintaining a constant volume of the power generating element. The restraining pressure may be, for example, 0.1 MPa or more and 50 MPa or less, or 1 MPa or more and 20 MPa or less.

[0034] The type of battery 10 is not particularly limited, but is typically an all-solid-state lithium-ion secondary battery. The use of battery 10 is not particularly limited, but examples include power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline-powered vehicles, and diesel-powered vehicles. In particular, it is preferable to use battery 10 as a driving power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). Battery 10 in the present disclosure may also be used as a power source for mobile objects other than vehicles (e.g., trains, ships, and aircraft), or as a power source for electrical appliances such as information processing devices.

[0035] 3.Negative electrode The negative electrode AN has the above-mentioned current collector 1, which is a negative electrode current collector, and a negative electrode active material layer 4 formed on the current collector 1. When the negative electrode current collector is used, it is preferable to use nickel foil, which is stable at the negative electrode potential, as the metal layer 2 of the current collector 1.

[0036] The negative electrode active material layer 4 contains at least a negative electrode active material. Examples of negative electrode active materials include Si-based active materials and carbon-based active materials. The Si-based active material is an active material containing Si element. Examples of Si-based active materials include simple Si, Si alloys, and Si oxides. The Si alloy preferably contains Si element as a main component. The proportion of Si element in the Si alloy is, for example, 50 mol % or more and 99 mol % or less. The negative electrode active material layer 4 preferably contains a negative electrode active material containing Si element. In the battery 10, the adhesion between the negative electrode active material layer 4 and the current collector 1 is high, so peeling of the negative electrode active material layer 4 from the current collector 1 due to expansion and contraction of the negative electrode active material containing Si element is suppressed.

[0037] The carbon-based active material is an inorganic active material containing the element C, and examples thereof include graphite, hard carbon, and soft carbon.

[0038] The shape of the negative electrode active material may be, for example, particulate or layered. 50 ) is, for example, 10 nm or more, and may be 100 nm or more. On the other hand, the average particle diameter (D 50 ) is, for example, 50 μm or less, and may be 20 μm or less. 50 ) refers to the cumulative 50% particle size in the volume-based particle size distribution measured by a laser diffraction particle size analyzer. The proportion of the negative electrode active material in the negative electrode active material layer 4 is, for example, 50% by weight or more and 80% by weight or less.

[0039] The negative electrode active material layer 4 is an inorganic material layer because it contains an inorganic negative electrode active material. The negative electrode active material layer 4 may contain at least one of a conductive material, a binder, and an electrolyte, as necessary.

[0040] Examples of binders include rubber-based binders such as butadiene rubber (BR), acrylate butadiene rubber (ABR), and styrene butadiene rubber (SBR), as well as fluorine-containing binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE).

[0041] Examples of conductive materials include carbon materials, such as particulate carbon materials such as acetylene black (AB) and ketjen black (KB), and fibrous carbon materials such as carbon fiber, carbon nanotubes (CNT), and carbon nanofibers (CNF).

[0042] Examples of the electrolyte include solid electrolytes. Examples of the solid electrolyte include inorganic solid electrolytes such as sulfide solid electrolytes, oxide solid electrolytes, and halide solid electrolytes. The sulfide solid electrolyte preferably contains sulfur (S) as the main component of the anion element. The oxide solid electrolyte preferably contains oxygen (O) as the main component of the anion element. The halide solid electrolyte preferably contains halogen as the main component of the anion. Among these, sulfide solid electrolytes are preferred.

[0043] Other examples of the solid electrolyte include organic solid electrolytes such as polymer electrolytes and gel electrolytes.

[0044] The thickness of the negative electrode active material layer 4 is not particularly limited, but is, for example, 0.5 μm or more and 1000 μm or less.

[0045] 4.Positive electrode The positive electrode CA has a positive electrode current collector 5 and a positive electrode active material layer 6 formed on the positive electrode current collector 5. The positive electrode current collector 5 is a member that collects electrons from the positive electrode active material layer 6. The material of the positive electrode current collector 5 is not particularly limited, and examples thereof include SUS, aluminum, nickel, iron, titanium, and carbon. The positive electrode current collector 5 may be in the form of, for example, a foil or a mesh.

[0046] The positive electrode active material layer 6 contains at least a positive electrode active material. Examples of the positive electrode active material include oxide active materials. Examples of the oxide active material include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 and LiNi 0.8 Co 0.15 Al 0.05 Examples of the positive electrode active material include rock salt layer-type active materials such as O2, spinel-type active materials such as LiMn2O4, and olivine-type active materials such as LiFePO4. Sulfur (S) may also be used as the positive electrode active material. The positive electrode active material may be, for example, in the form of particles.

[0047] The positive electrode active material layer 6 may contain at least one of a conductive material, a binder, and a solid electrolyte, as necessary. The conductive material, the binder, and the solid electrolyte are the same as those described in "3. Negative electrode."

[0048] The thickness of the positive electrode active material layer 6 is not particularly limited, but is, for example, 0.1 μm or more and 1000 μm or less.

[0049] 5.Solid electrolyte layer The solid electrolyte layer EL is disposed between the positive electrode CA and the negative electrode AN. More specifically, the solid electrolyte layer EL is disposed between the positive electrode active material layer 6 and the negative electrode active material layer 4.

[0050] The solid electrolyte layer EL contains at least a solid electrolyte. The solid electrolyte layer EL may also contain a binder, if necessary. The solid electrolyte and binder are the same as those described in "3. Negative electrode." The thickness of the solid electrolyte layer EL is, for example, 1 μm or more and 500 μm or less.

[0051] As described above, in the battery 10 according to the first embodiment, the current collector 1, which is the negative electrode current collector of the negative electrode AN, has the metal layer 2 and the resin layer 3 formed on the metal layer 2. The resin layer 3 contains a silane coupling agent and faces the negative electrode active material layer 4. The silane coupling agent contained in the resin layer 3 chemically bonds the negative electrode active material layer 4 and the current collector 1. Therefore, the battery 10 has improved adhesion between the negative electrode active material layer 4 and the current collector 1.

[0052] Next, an example of a method for manufacturing the battery 10 according to the first embodiment will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a flowchart showing the method for manufacturing the battery according to the first embodiment. Fig. 4 is a schematic cross-sectional view illustrating the method for manufacturing the battery according to the first embodiment. As shown in Figs. 3 and 4, the method for manufacturing the battery 10 according to the first embodiment includes steps S1 to S6.

[0053] Step S1 is a current collector preparation step in which a current collector 1 is prepared. Step S2 is a negative electrode coating step in which a negative electrode active material layer-forming composition 4a, which will become the negative electrode active material layer 4, is applied to the current collector 1. Step S3 is a negative electrode drying step in which the negative electrode active material layer-forming composition 4a applied to the current collector 1 is dried. Step S3 results in a negative electrode AN in which the negative electrode active material layer 4 is formed on the current collector 1. Step S4 is a sealing step in which a solid electrolyte layer EL is applied to the negative electrode active material layer 4 of the negative electrode AN, and then the negative electrode AN and the solid electrolyte layer EL are sealed with a metal substrate 7. Step S4 results in a laminate 8 in which the negative electrode AN and the solid electrolyte layer EL are stacked, and the laminate 8 is sealed with the substrate 7. Step S5 is a transfer step in which the laminate 8 sealed with the substrate 7 is pressed from both sides in the stacking direction to transfer the solid electrolyte layer EL to the negative electrode active material layer 4. For example, a roll press device having a pair of rolls 9 can be used for pressing. Step S6 is a transfer success / failure confirmation step in which, after the substrate 7 has been peeled off from the laminate 8, it is confirmed whether the solid electrolyte layer EL has been successfully transferred.

[0054] Here, the press used during transfer is a high-pressure press that applies a load of, for example, 1 to 500 MPa to the negative electrode AN. When battery 10 is produced by such a production method, the high adhesion between the negative electrode active material layer 4 and the current collector 1 prevents the negative electrode active material layer 4 from peeling off from the current collector 1 due to the high-pressure press used during transfer.

[0055] Next, Fig. 5 is a diagram illustrating the bonding of the negative electrode active material layer and the current collector. When 3-trimethoxysilylpropylsuccinic anhydride is used as the silane coupling agent contained in the resin layer 3, the silane coupling agent bonds the negative electrode active material layer 4 of the negative electrode AN to the current collector 1 as shown in Fig. 5.

[0056] Although the specific reaction mechanism is unknown, it is believed that the silane coupling agent and the negative electrode active material layer 4 form a chemical bond through a condensation reaction between a silanol group generated by hydrolysis of a methoxy group in the silane coupling agent molecule and a hydroxyl group on the surface of the negative electrode active material layer 4 (negative electrode active material). On the other hand, although the specific reaction mechanism is unknown, it is believed that the silane coupling agent and the resin layer 3 form a chemical bond through a ring-opening reaction between an acid anhydride group in the silane coupling agent molecule and a functional group of the resin contained in the resin layer 3.

[0057] The present disclosure is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present disclosure and that provides similar effects is included within the technical scope of the present disclosure.

[0058] The current collector 1 and the battery 10 according to the first embodiment will be further described below based on examples.

[0059] [Example 1] (Preparation of current collector) A mixture containing polyimide as a resin, dimethylacetamide as a solvent, styrene-maleic anhydride as a dispersant, acetylene black as an additive, and 3-trimethoxysilylpropylsuccinic anhydride (X-12-967C, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent was stirred using an ultrasonic disperser to obtain a slurry-like resin layer-forming composition. The resin layer-forming composition was then applied to a nickel foil serving as the metal layer 2 using a blade method and dried on a hot plate at 80°C for 15 minutes. This was followed by further drying on a hot plate at 170°C for 30 minutes to form a polyimide layer serving as the resin layer 3 on the nickel foil. This resulted in a current collector 1 having the metal layer 2 and the resin layer 3 formed on the metal layer 2. The polyimide used was solvent-soluble and colorless and transparent. The glass transition temperature of the polyimide was 140°C or higher.

[0060] In Example 1, the blending amount of 3-trimethoxysilylpropylsuccinic anhydride relative to the polyimide was set to 0.5% by mass.

[0061] (Preparation of negative electrode) A mixture containing a Si-based active material as the negative electrode active material, a sulfide-based solid electrolyte (SE; Li2S-P2S5), PVdF as a binder, butyl butyrate, and heptane was stirred using an ultrasonic disperser to obtain a slurry-like composition for forming a negative electrode active material layer. The weight ratio of the negative electrode active material, SE, and PVdF was adjusted to 52.7:43.9:3.4. This composition for forming a negative electrode active material layer was applied to the resin layer 3 of the current collector 1 by a blade method and dried on a hot plate at 50°C for 20 minutes. This was then further dried on a hot plate at 150°C for 30 minutes to obtain a negative electrode AN.

[0062] (Preparation of solid electrolyte layer) A mixture containing a sulfide-based solid electrolyte (SE; Li2S-P2S5), acrylonitrile butadiene rubber (ABR) as a binder, butyric acid, and butylheptane was stirred using an ultrasonic disperser to obtain a slurry-like SE-forming composition. The weight ratio of SE to ABR was adjusted to 99.4:0.6. This SE-forming composition was applied to a SUS foil substrate (7) using a blade method and dried on a hot plate at 50°C for 1 minute. This was then further dried on a hot plate at 150°C for 30 minutes to obtain a solid electrolyte layer EL formed on the substrate (7).

[0063] [Example 2] A current collector 1 was produced in the same manner as in Example 1, except that the blending amount of 3-trimethoxysilylpropylsuccinic anhydride relative to the polyimide was 1.0 mass %. Then, a negative electrode AN of Example 2 was produced in the same manner as in Example 1.

[0064] [Example 3] A current collector 1 was produced in the same manner as in Example 1, except that the blending amount of 3-trimethoxysilylpropylsuccinic anhydride relative to the polyimide was 1.5 mass %. Then, a negative electrode AN of Example 3 was produced in the same manner as in Example 1.

[0065] [Example 4] A current collector 1 was produced in the same manner as in Example 1, except that the blending amount of 3-trimethoxysilylpropylsuccinic anhydride relative to the polyimide was 2.0 mass %. Then, a negative electrode AN of Example 4 was produced in the same manner as in Example 1.

[0066] [Reference example 1] A current collector was produced in the same manner as in Example 1, except that the blending amount of 3-trimethoxysilylpropylsuccinic anhydride relative to the polyimide was set to 0.25 mass %. Then, a negative electrode of Reference Example 1 was produced in the same manner as in Example 1.

[0067] [Reference example 2] A current collector was produced in the same manner as in Example 1, except that the blending amount of 3-trimethoxysilylpropylsuccinic anhydride relative to the polyimide was 4.0 mass %. Then, a negative electrode of Reference Example 2 was produced in the same manner as in Example 1.

[0068] [Comparative Example] A current collector was prepared in the same manner as in Example 1, except that the blending amount of 3-trimethoxysilylpropylsuccinic anhydride relative to the polyimide was set to 0% by mass. That is, a current collector was prepared in which a resin layer containing no silane coupling agent was formed on a metal layer. Then, a negative electrode of the comparative example was prepared in the same manner as in Example 1.

[0069] (Solid electrolyte layer transferability confirmation test) A transferability test of the solid electrolyte layer was conducted on the negative electrodes of Examples 1 to 4, Reference Examples 1 and 2, and the Comparative Example. In the transferability test, the negative electrode and solid electrolyte layer were first cut into 2 cm x 7 cm pieces and stacked in the following order: current collector / negative electrode active material layer / solid electrolyte layer / substrate. This resulted in a test stack consisting of the current collector, negative electrode active material layer, and solid electrolyte layer stacked together, which was then sealed with the substrate. Specifically, in the negative electrodes of Examples 1 to 4 and Reference Examples 1 and 2, the metal layer / resin layer / negative electrode active material layer / solid electrolyte layer / substrate was stacked in this order. Furthermore, in the negative electrode of the Comparative Example, the metal layer / negative electrode active material layer / solid electrolyte layer / substrate was stacked in this order.

[0070] The substrate and the test laminate were then roll-pressed to check whether the solid electrolyte layer could be transferred to the negative electrode active material layer. In the roll-press, a load of 60 kN (30 kN / cm) was applied to the test laminate.

[0071] As a result of the above-mentioned transferability confirmation test, it was found that for the test laminates in which the blending amount of the silane coupling agent relative to the polyimide was 0 mass % and 0.25 mass %, the blending amount of the silane coupling agent was small and the bonding strength with the electrode material was weak, so the solid electrolyte layer could not be transferred onto the negative electrode active material layer.

[0072] On the other hand, for the test laminates in which the blending amount of silane coupling agent relative to polyimide was 0.5 mass%, 1.0 mass%, 1.5 mass%, 2.0 mass%, and 4.0 mass%, a solid electrolyte layer could be transferred onto the negative electrode active material layer.

[0073] Thus, it was confirmed that the negative electrodes of Examples 1 to 4 and Reference Examples 1 and 2 were capable of transferring the solid electrolyte layer onto the negative electrode active material layer.

[0074] (Negative electrode peeling test) A peeling test was carried out on the negative electrodes of Examples 1 to 4, Reference Examples 1 and 2, and the Comparative Example. In the peeling test, the negative electrodes were subjected to isostatic pressing (CIP) and then punched out to a size of φ14.5 cm to prepare test negative electrodes. In the isostatic pressing, a load of 25 MPa was applied to the negative electrodes for 1 minute.

[0075] After the hydrostatic press, a peel strength test was carried out on the test negative electrode using a peel strength tester (Model-2257, manufactured by Aiko Engineering) to measure the peel strength, which indicates the adhesion between the negative electrode active material layer and the current collector.

[0076] The results of the above-mentioned peel test are shown in Figure 6. Figure 6 is a graph showing the results of the peel test. The horizontal axis of the graph shown in Figure 6 represents the blending amount (mass%) of the silane coupling agent relative to the polyimide. The vertical axis of the graph shown in Figure 6 represents the peel strength (MPa).

[0077] As can be seen from the results of the peel test, for the test negative electrodes with 0 mass%, 0.25 mass%, and 4.0 mass% silane coupling agent mixed with polyimide, the negative electrode active material layer peeled off from the current collector due to the hydrostatic press, so no peel strength measurements could be obtained. The reason for the peeling of the negative electrode active material layer from the current collector is thought to be that the strain stress generated by the hydrostatic press was greater than the strain stress generated by the press during transfer.

[0078] On the other hand, test negative electrodes in which the blending amounts of silane coupling agent relative to polyimide were 0.5 mass %, 1.0 mass %, 1.5 mass %, and 2.0 mass % exhibited peel strengths of 0.010 to 0.017 MPa.

[0079] Thus, it was confirmed that the negative electrodes of Examples 1 to 4 had higher peel strength than the negative electrodes of Reference Examples 1 and 2 and the Comparative Example. [Explanation of symbols]

[0080] 1 current collector 2 metal layer 3 resin layer 4 Negative electrode active material layer 4a Composition for forming negative electrode active material layer 5 Positive electrode current collector 6 Positive electrode active material layer 7 Base material 8 Laminate 9 rolls 10 batteries AN Negative electrode CA Positive electrode EL Solid electrolyte layer

Claims

1. a metal layer; a resin layer formed on the metal layer, The resin layer of the current collector contains a silane coupling agent.

2. 2 . The current collector according to claim 1 , wherein the amount of the silane coupling agent relative to the resin contained in the resin layer is 0.5% by mass or more and 2.0% by mass or less, when the amount of the resin contained in the resin layer is 100% by mass.

3. The current collector according to claim 1 , wherein the resin layer contains a thermoplastic resin having a glass transition point of 140° C. or higher.

4. A positive electrode and a negative electrode including a current collector and a negative electrode active material layer; a solid electrolyte layer disposed between the positive electrode and the negative electrode, The current collector is a metal layer; a resin layer formed on the metal layer, The resin layer is A battery containing a silane coupling agent facing the negative electrode active material layer.

5. The battery according to claim 4 , wherein the negative electrode active material layer comprises a negative electrode active material containing elemental Si.

Images