Negative electrode, lithium ion secondary battery, method for manufacturing a negative electrode for a lithium ion secondary battery, and method for manufacturing a negative electrode sheet for a lithium ion secondary battery

Abstract

To provide an insulator layer which is superior in the performance of insulation between positive and negative electrodes of a lithium ion secondary battery.SOLUTION: A negative electrode 100 for a lithium ion secondary battery comprises: a current collector 110; and a negative electrode active material layer 120 formed on the current collector and containing at least a negative electrode active material and a binding material. The negative electrode 100 for a lithium ion secondary battery further comprises: an insulator layer 300 on the surface of the negative electrode active material layer 120, which contains at least an insulative substance and a binding material. The binding material included in the insulator layer 300 contains at least a styrene butadiene rubber, and at least one kind selected from a group consisting of a carboxymethylcellulose and its salt. The binding material included in the negative electrode active material layer 120 is at least one kind selected from a group consisting of polyacrylic acid and its salt.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a negative electrode, a lithium-ion secondary battery, a method for manufacturing a negative electrode for a lithium-ion secondary battery, and a method for manufacturing a negative electrode sheet for a lithium-ion secondary battery.

Background Art

[0002] A lithium-ion secondary battery includes a negative electrode, a positive electrode, and a separator interposed between the negative electrode and the positive electrode. Patent Document 1 discloses a non-aqueous secondary battery in which a negative electrode having a negative electrode active material layer containing a negative electrode active material and a binder, a positive electrode, a separator, and a non-aqueous electrolyte are housed in an exterior body. This Patent Document 1 describes that a porous film is used for the separator, and a heat-resistant porous layer containing a heat-resistant inorganic filler is formed on the surface thereof.

[0003] In the structure described in Patent Document 1, since the electrode and the heat-resistant layer on the separator are not integrated, when the base material contracts during heat generation, the heat-resistant layer adhered to the base material side also moves accordingly, so that it cannot be said that the insulating function between the positive electrode and the negative electrode is sufficient.

[0004] Patent Document 2 describes a method for manufacturing a lithium-ion secondary battery that does not include a separator. In the manufacturing method described in the patent document, it has a laminated structure in which an electrode active material layer and an insulating layer are arranged in this order, and an active material layer material is applied to at least one surface of the electrode current collector to form a first coating film, and an insulating layer material is coated on the first coating film to form a second coating film, and then the first coating film and the second coating film are dried simultaneously. 2

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the case of a simultaneous drying method in which an insulating layer material is coated on the first coating film to form a second coating film and then the first coating film and the second coating film are dried simultaneously, the insulating layer material penetrates into the active material layer material. As a result, a mixed layer is formed between the active material layer and the insulating layer. When this mixed layer is formed, the adhesion strength between the active material layer and the insulating layer increases. However, if the insulating material penetrates too much into the active material, there is a possibility that the active material layer is exposed on the surface of the insulating layer. In this case, the insulating performance of the insulating layer will decrease.

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to enhance the adhesion between the active material layer and the insulating layer (high resistance layer) while preventing the insulating performance of the insulating layer (high resistance layer) from decreasing when forming the insulating layer (high resistance layer) on the active material layer.

Means for Solving the Problems

[0008] In each aspect of the present invention, in order to solve the above-described problems, the following configurations are adopted respectively.

[0009] The first aspect relates to a negative electrode for a lithium-ion secondary battery. The negative electrode for a first lithium-ion secondary battery according to the first aspect is on a current collector, a negative electrode for a lithium-ion secondary battery in which a negative electrode active material layer containing at least a negative electrode active material and a binder is formed, further having an insulating layer containing at least an insulating substance and a binder on the surface of the negative electrode active material layer, the binder contained in the insulating layer contains at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts, the binder contained in the negative electrode active material layer is at least one selected from polyacrylic acid and its salts.

[0010] The negative electrode for a second lithium-ion secondary battery according to the first aspect is a negative electrode for an all-solid-state lithium-ion secondary battery, on a current collector, a negative electrode for a lithium-ion secondary battery in which a negative electrode active material layer containing at least a negative electrode active material and a binder is formed, further having a high-resistance layer containing at least a solid electrolyte and a binder on the surface of the negative electrode active material layer, the binder contained in the high-resistance layer contains at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts, the binder contained in the negative electrode active material layer is at least one selected from polyacrylic acid and its salts.

[0011] The second aspect relates to a lithium-ion secondary battery. The first lithium-ion secondary battery according to the second aspect is a lithium-ion secondary battery including a positive electrode in which a positive electrode active material layer is formed on a current collector, a negative electrode, and an electrolyte, wherein the negative electrode is the negative electrode for a lithium-ion secondary battery according to the first aspect.

[0012] The second lithium-ion secondary battery according to the second aspect is an all-solid-state lithium-ion secondary battery including a positive electrode in which a positive electrode active material layer is formed on a current collector, a negative electrode, and a solid electrolyte, wherein the negative electrode is the negative electrode for an all-solid-state lithium-ion secondary battery according to the first aspect.

[0013] The third aspect relates to a method for manufacturing a negative electrode for a lithium-ion secondary battery. The method for manufacturing a negative electrode for a first lithium-ion secondary battery according to the third aspect is on a sheet-shaped current collector, (A) a step of applying a negative electrode active material slurry containing at least a negative electrode active material and a binder, (B) A step of applying an insulating layer slurry containing at least an insulating material and a binder on the surface of the negative electrode active material slurry; (C) A step of simultaneously drying the slurries applied in the step (A) and the step (B); A method for manufacturing a negative electrode for a lithium-ion secondary battery, including at least these steps in this order, The binder contained in the insulating layer slurry includes at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts, The binder contained in the negative electrode active material slurry is at least one selected from polyacrylic acid and its salts.

[0014] A method for manufacturing a negative electrode for a lithium-ion secondary battery according to a third aspect, A method for manufacturing a negative electrode for an all-solid-state lithium-ion secondary battery, On a sheet-shaped current collector, (A) A step of applying a negative electrode active material slurry containing at least a negative electrode active material and a binder; (B) A step of applying a high-resistance layer slurry containing at least a solid electrolyte and a binder on the surface of the negative electrode active material slurry; (C) A step of simultaneously drying the slurries applied in the step (A) and the step (B); A method for manufacturing a negative electrode for an all-solid-state lithium-ion secondary battery, including at least these steps in this order, The binder contained in the high-resistance layer slurry includes at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts, The binder contained in the negative electrode active material slurry is at least one selected from polyacrylic acid and its salts.

[0015] A fourth aspect relates to a method for manufacturing a negative electrode sheet for a lithium-ion secondary battery. A first method for manufacturing a negative electrode sheet for a lithium-ion secondary battery according to a fourth aspect, A method for manufacturing a negative electrode sheet for a lithium-ion secondary battery for manufacturing a negative electrode for a lithium-ion secondary battery according to a third aspect, including a step of continuously applying a negative electrode active material slurry containing at least a negative electrode active material and a binder, and an insulating layer slurry containing at least an insulating material and a binder in a direction in which the current collector sheet is continuously conveyed.

[0016] A method for manufacturing a second negative electrode sheet for a lithium-ion secondary battery according to a fourth aspect, is a method for manufacturing a negative electrode sheet for an all-solid-state lithium-ion secondary battery for manufacturing a negative electrode for an all-solid-state lithium-ion secondary battery according to a manufacturing method according to a third aspect, including a step of continuously applying a negative electrode active material slurry containing at least a negative electrode active material and a binder, and a high-resistance layer slurry containing at least a solid electrolyte and a binder in a direction in which the current collector sheet is continuously conveyed.

[0017] In addition, any combination of the above components, and those obtained by converting the expression of the present invention among methods, apparatuses, systems, recording media, computer programs, etc. are also effective as aspects of the present invention.

[0018] Also, the various components of the present invention do not necessarily have to exist independently of each other. It is also possible that a plurality of components are formed as one member, one component is formed of a plurality of members, a certain component is a part of another component, a part of a certain component and a part of another component overlap, and the like.

[0019] Also, although a plurality of procedures are described in order in the method of the present invention, the described order does not limit the order of executing the plurality of procedures. Therefore, when implementing the method of the present invention, the order of the plurality of procedures can be changed within a range that does not cause any problem in terms of content.

[0020] Furthermore, the plurality of steps of the method of the present invention are not limited to being executed at different timings individually. Therefore, other steps may occur during the execution of a certain step, or part or all of the execution timing of a certain step may overlap with the execution timing of other steps, and so on.

Advantages of the Invention

[0021] According to the above-described aspect of the present invention, an insulating layer or a high-resistance layer excellent in the insulating performance between the positive electrode and the negative electrode of the lithium-ion secondary battery can be provided.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0023] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and the description will be omitted as appropriate.

[0024] In this specification, ordinal numbers such as "first", "second", "third", etc. are, unless otherwise specified, attached merely to distinguish components with the same name, and do not mean specific features of the components (e.g., order or importance).

[0025] FIG. 1 is a top view of a lithium-ion secondary battery 10 according to an embodiment. FIG. 2 is a view obtained by removing a first lead 150, a second lead 250, and an exterior member 400 from FIG. 1. In other words, FIG. 2 is a top view of a laminate 12. FIG. 3 is a cross-sectional view taken along line A-A' of FIG. 2.

[0026] In FIGS. 1 to 3, a first direction X indicates the length direction of the lithium-ion secondary battery 10 (laminate 12). The negative direction of the first direction X (the direction indicated by the arrow showing the first direction X) is the direction from the first lead 150 toward the second lead 250. The negative direction of the first direction X (the opposite direction of the direction indicated by the arrow showing the first direction X) is the direction from the second lead 250 toward the first lead 150. A second direction Y indicates the width direction of the lithium-ion secondary battery 10 (laminate 12). The negative direction of the second direction Y (the direction indicated by the arrow showing the second direction Y) is the left direction of the lithium-ion secondary battery 10 (laminate 12) when the lithium-ion secondary battery 10 is viewed from the positive direction of the first direction X. The positive direction of the second direction Y (the opposite direction of the direction indicated by the arrow showing the second direction Y) is the right direction of the lithium-ion secondary battery 10 (laminate 12) when the lithium-ion secondary battery 10 is viewed from the positive direction of the first direction X. A third direction Z is the thickness (height) direction of the lithium-ion secondary battery 10 (laminate 12). The negative direction of the third direction Z (the direction indicated by the arrow showing the third direction Z) is the upward direction of the lithium-ion secondary battery 10 (laminate 12). The positive direction of the third direction Z (the opposite direction of the direction indicated by the arrow showing the third direction Z) is the downward direction of the lithium-ion secondary battery 10 (laminate 12).

[0027] The outline of the negative electrode 100 according to this embodiment will be described with reference to FIG. 3. The negative electrode 100 has a negative electrode active material layer 120 formed on a negative electrode current collector 110, the negative electrode active material layer 120 containing at least a negative electrode active material and a binder. Further, on the surface of the negative electrode active material layer 120, there is an insulating layer 300 containing at least an insulating material and a binder. The binder contained in the insulating layer 300 contains at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts. The binder contained in the negative electrode active material layer 120 is at least one selected from polyacrylic acid and its salts.

[0028] The lithium-ion secondary battery 10 will be described with reference to FIGS. 1 and 2.

[0029] The lithium-ion secondary battery 10 includes a laminate 12, a first lead 150, a second lead 250, and an exterior member 400.

[0030] The first lead 150 is electrically connected to the negative electrode 100 (for example, FIG. 3). The first lead 150 may be formed of, for example, copper or a copper alloy, or those plated with nickel.

[0031] The second lead 250 is electrically connected to the positive electrode 200 (for example, FIG. 3). The second lead 250 may be formed of, for example, aluminum or an aluminum alloy.

[0032] The exterior member 400 has a rectangular shape with four sides. In the present embodiment, the second lead 250 is provided on the side of the exterior member 400 located on the positive direction side of the first direction X, and the first lead 150 is provided on the side of the exterior member 400 located on the negative direction side of the first direction X. However, the second lead 250 and the first lead 150 may be provided on a common side of the exterior member 400 (for example, the side located on the negative direction side or the positive direction side of the first direction X).

[0033] Each cell of the lithium-ion secondary battery 10 includes a negative electrode 100, a positive electrode 200, and an electrolyte (not shown). The state of the electrolyte may be any of liquid, gel, and solid. In this embodiment, the state of the electrolyte of the lithium-ion secondary battery 10 is liquid, and will be described as "electrolyte solution". The manufacturing process in the case of using a solid electrolyte will be described later. The exterior material 400 houses the laminate 12 together with an electrolyte solution (not shown).

[0034] The exterior material 400 may include, for example, a heat-sealable resin layer and a barrier layer, and may be a laminated film including, for example, a heat-sealable resin layer and a barrier layer.

[0035] The resin material forming the heat-sealable resin layer may be, for example, polyethylene (PE), polypropylene, nylon, polyethylene terephthalate (PET), or the like. The thickness of the heat-sealable resin layer is, for example, 20 μm or more and 200 μm or less.

[0036] The barrier layer has barrier properties such as preventing leakage of the electrolyte solution or intrusion of moisture from the outside, and may be a barrier layer formed of a metal such as stainless steel (SUS) foil, aluminum foil, aluminum alloy foil, copper foil, titanium foil, or the like. The thickness of the barrier layer is, for example, 10 μm or more and 100 μm or less.

[0037] The heat-sealable resin layer of the laminated film may be one layer, or may be two or more layers. Similarly, the barrier layer of the laminated film may be one layer, or may be two or more layers.

[0038] The electrolyte solution is, for example, a non-aqueous electrolyte solution. This non-aqueous electrolyte solution may contain a lithium salt and a solvent for dissolving the lithium salt.

[0039] The lithium salt is, for example, LiClO4, LiBF6, LiPF6, LiCF3SO3, LiCF3CO2, LiAsF6, LiSbF6, LiB 10 Cl 10, it may also be LiAlCl4, LiCl, LiBr, LiB(C2H5)4, CF3SO3Li, CH3SO3Li, LiC4F9SO3, Li(CF3SO2)2N, lithium lower fatty acid carboxylate, etc.

[0040] The solvent for dissolving the lithium salt is, for example, carbonates such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), vinylene carbonate (VC); lactones such as γ-butyrolactone, γ-valerolactone; ethers such as trimethoxymethane, 1,2-dimethoxyethane, diethyl ether, tetrahydrofuran, 2-methyltetrahydrofuran; sulfoxides such as dimethyl sulfoxide; oxolanes such as 1,3-dioxolane, 4-methyl-1,3-dioxolane; nitrogen-containing solvents such as acetonitrile, nitromethane, formamide, dimethylformamide; organic acid esters such as methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate; triphosphate esters and diglymes; triglymes; sulfolanes such as sulfolane, methyl sulfolane; oxazolidinones such as 3-methyl-2-oxazolidinone; sultones such as 1,3-propane sultone, 1,4-butane sultone, naphthalene sultone, etc. These substances may be used alone or in combination.

[0041] The laminate 12 will be described with reference to FIG. 3.

[0042] The laminate 12 has a plurality of negative electrodes 100 coated with an insulating layer 300 and a plurality of positive electrodes 200. Each negative electrode 100 and each positive electrode 200 coated with the insulating layer 300 are alternately laminated in the third direction Z. Each insulating layer 300 is located between the adjacent positive electrode 200 and negative electrode 100 in the third direction Z. However, the laminate 12 may have only one negative electrode 100 and only one positive electrode 200 coated with the insulating layer 300.

[0043] However, the laminate 12 is not excluded from having a configuration that combines a general polyolefin-based film separator. In this case, the laminate 12 may have a structure in which the negative electrode 100 and the positive electrode 200 are "laminated" via a separator (even a single layer), a "wound" structure in which the negative electrode 100 and the positive electrode 200 are stacked and wound around a long separator, and a "pleated" structure in which the negative electrode 100 and the positive electrode 200 are pleated via a long separator. Further, the laminate 12 may have a structure in which a plurality of laminates 12 having a "laminated" structure are further wound around a long separator or pleated.

[0044] As an example, in the above "pleated" structure, the separator may be pleated and extended along the first direction X on the outside in the first direction X of the negative electrode 100 or the positive electrode 200 coated with the insulating layer 300, while passing between the adjacent negative electrode 100 and positive electrode 200 when folded back along the first direction X.

[0045] Details of the negative electrode 100 will be described. The negative electrode 100 has a negative electrode current collector 110 and a negative electrode active material layer 120.

[0046] The negative electrode current collector 110 of the negative electrode 100 has a first surface 112 and a second surface 114. The first surface 112 of the negative electrode current collector 110 is the upper surface of the negative electrode current collector 110. The second surface 114 of the negative electrode current collector 110 is on the opposite side of the first surface 112 of the negative electrode current collector 110 and is the lower surface of the negative electrode current collector 110.

[0047] The negative electrode active material layer 120 is located on the first surface 112 of the negative electrode current collector 110. Another negative electrode active material layer 120 is located on the second surface 114 of the negative electrode current collector 110. However, the negative electrode active material layer 120 may be located on only one of the first surface 112 and the second surface 114 of the negative electrode current collector 110.

[0048] The end portion of the negative electrode current collector 110 on the negative direction side in the first direction X is connected to the first lead 150 (FIG. 1). For example, in the third direction Z, when the end portion of the negative electrode current collector 110 on the negative direction side in the first direction X and the first lead 150 are displaced, the end portion of the negative electrode current collector 110 on the negative direction side in the first direction X may be bent toward the first lead 150.

[0049] The negative electrode current collector 110 may be formed of, for example, copper, stainless steel, nickel, titanium, or an alloy thereof. The shape of the negative electrode current collector 110 may be, for example, a foil, a flat plate, or a mesh. The thickness (in the third direction Z) of the negative electrode current collector 110 in the third direction Z is, for example, 1 μm or more and 50 μm or less.

[0050] The negative electrode active material layer 120 contains a negative electrode active material and a binder resin. The negative electrode active material layer 120 may further contain a conductive assistant as needed.

[0051] The negative electrode active material is not particularly limited as long as it is a normal negative electrode active material that can be used for the negative electrode 100 of the lithium ion secondary battery 10. For example, carbon materials such as graphite that occludes lithium, amorphous carbon, diamond-like carbon, fullerene, carbon nanotubes, carbon nanohorns; lithium-based metal materials such as lithium metal and lithium alloys; Si-based materials such as Si, SiO2, SiOx (0 < x ≤ 2), and Si-containing composite materials; conductive polymer materials such as polyacene, polyacetylene, and polypyrrole. The negative electrode active material may be used alone or in combination of two or more.

[0052] The negative electrode active material layer 120 contains, for example, 90 parts by mass or more and 99 parts by mass or less of the negative electrode active material with respect to 100 parts by mass of the total mass of the negative electrode active material layer 120.

[0053] The average particle size of the negative electrode active material is preferably 1 μm or more, more preferably 2 μm or more, from the viewpoint of suppressing side reactions during charge and discharge and suppressing a decrease in charge and discharge efficiency. From the viewpoints of input / output characteristics and the production of the negative electrode 100 (such as the smoothness of the surface of the negative electrode 100), it is preferably 100 μm or less, more preferably 50 μm or less. Here, the average particle size means the particle size (median diameter: D50) at the integrated value of 50% in the particle size distribution (volume basis) by the laser diffraction scattering method.

[0054] The density of the negative electrode active material layer 120 is, for example, 1.2 g / cm 3 or more and 2.0 g / cm 3 or less.

[0055] The thickness (in the third direction Z) of the negative electrode active material layer 120 on one of the two surfaces (the first surface 112 and the second surface 114) of the negative electrode current collector 110 can be appropriately determined. The thickness is, for example, 80 μm or less.

[0056] The total thickness (in the third direction Z) of the negative electrode active material layer 120 on the two surfaces (the first surface 112 and the second surface 114) of the negative electrode current collector 110 can be appropriately determined. The thickness is, for example, 160 μm or less.

[0057] The binder resin contained in the negative electrode active material layer 120 can be, for example, a rubber-based binder (such as SBR (styrene-butadiene rubber)) or an acrylic-based binder resin when water is used as the solvent for obtaining the slurry. Such an aqueous binder resin may be in an emulsion form. When water is used as the solvent, it is preferable to use an aqueous binder and a thickener such as CMC (carboxymethyl cellulose) in combination.

[0058] The amount of the binder resin contained in the negative electrode active material layer 120 can be appropriately determined. The negative electrode active material layer 120 contains, for example, 1.0 part by mass or more and 10.0 parts by mass or less of the binder resin with respect to 100 parts by mass of the total mass of the negative electrode active material layer 120, and more preferably contains 3 parts by mass or more and 6 parts by mass or less of the binder resin.

[0059] Of the total weight of the solid materials constituting the negative electrode active material layer 120, the total weight of the polyacrylic acid and its salts among the binders contained in the negative electrode active material layer 120 is 3% by weight or more and 6% by weight or less.

[0060] Details of the positive electrode 200 will be described. The positive electrode 200 has a positive electrode current collector 210 and a positive electrode active material layer 220.

[0061] The positive electrode current collector 210 of the positive electrode 200 has a third surface 212 and a fourth surface 214. The third surface 212 of the positive electrode current collector 210 is the lower surface of the positive electrode current collector 210. The fourth surface 214 of the positive electrode current collector 210 is on the opposite side of the third surface 212 of the positive electrode current collector 210 and is the upper surface of the positive electrode current collector 210.

[0062] The positive electrode active material layer 220 is located on the third surface 212 of the positive electrode current collector 210. Another positive electrode active material layer 220 is located on the fourth surface 214 of the positive electrode current collector 210. However, the positive electrode active material layer 220 may be located on only one of the third surface 212 and the fourth surface 214 of the positive electrode current collector 210.

[0063] The end portion on the positive direction side of the first direction X of the positive electrode current collector 210 is connected to the second lead 250 (FIG. 1). For example, in the third direction Z, when the end portion on the positive direction side of the first direction X of the positive electrode current collector 210 and the second lead 250 are displaced, the end portion on the positive direction side of the first direction X of the positive electrode current collector 210 may be bent toward the second lead 250.

[0064] The positive electrode current collector 210 may be formed of, for example, aluminum, stainless steel, nickel, titanium, or an alloy thereof. The shape of the positive electrode current collector 210 may be, for example, a foil, a flat plate, or a mesh. The thickness (third direction Z) of the positive electrode current collector 210 is, for example, 1 μm or more and 50 μm or less.

[0065] The positive electrode active material layer 220 contains a positive electrode active material, a binder resin, and a conductive assistant.

[0066] The positive electrode active material is not particularly limited as long as it is a normal positive electrode active material that can be used for the positive electrode 200 of the lithium-ion secondary battery 10. For example, 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, lithium-nickel-cobalt-manganese-aluminum composite oxide; transition metal sulfides such as TiS2, FeS, MoS2; transition metal oxides such as MnO, V2O5, V6O 13 、TiO2, etc.; olivine-type lithium phosphate oxides, etc. The olivine-type lithium phosphate oxide 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, lithium, phosphorus, and oxygen. These compounds may be those in which some elements are partially substituted with other elements in order to improve their properties. Among these, olivine-type lithium iron phosphate oxide, 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, lithium-nickel-cobalt-manganese-aluminum composite oxide are preferred. In addition to having a high working potential, these positive electrode active materials also have a large capacity and a large energy density. The positive electrode active material may be used alone or in combination of two or more.

[0067] The positive electrode active material layer 220 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 220.

[0068] The average particle size of the positive electrode active material contained in the positive electrode active material layer 220 is preferably 1 μm or more, more preferably 2 μm or more, from the viewpoint of suppressing side reactions during charge and discharge and suppressing a decrease in charge and discharge efficiency. From the viewpoints of input / output characteristics and production of the positive electrode 200 (such as the smoothness of the surface of the positive electrode 200), it is preferably 100 μm or less, more preferably 50 μm or less. Here, the average particle size means the particle size (median diameter: D50) at the integrated value of 50% in the particle size distribution (volume basis) by the laser diffraction scattering method.

[0069] The density of the positive electrode active material layer 220 is, for example, 2.0 g / cm 3 or more and 4.0 g / cm 3 or less.

[0070] The thickness (in the third direction Z) of the positive electrode active material layer 220 on one of the two surfaces (the third surface 212 and the fourth surface 214) of the positive electrode current collector 210 can be appropriately determined. The thickness is, for example, 100 μm or less. The total thickness (in the third direction Z) of the positive electrode active material layer 220 on the two surfaces (the third surface 212 and the fourth surface 214) of the positive electrode current collector 210 can be appropriately determined. The thickness is, for example, 200 μm or less.

[0071] The binder resin contained in the positive electrode active material layer 220 is, for example, polytetrafluoroethylene (PTFE) or polyvinylidene fluoride (PVDF).

[0072] The amount of the binder resin contained in the positive electrode active material layer 220 can be appropriately determined. The positive electrode active material layer 220 contains, for example, 0.1 part by mass or more and 10.0 parts by mass or less of the binder resin with respect to 100 parts by mass of the total mass of the positive electrode active material layer 220.

[0073] The conductive assistant contained in the positive electrode active material layer 220 is, for example, carbon black, ketjen black, acetylene black, natural graphite, artificial graphite, carbon nanotube 、andThey are carbon fibers or the like. The graphite may be, for example, flake graphite or spherical graphite. These substances may be used alone or in combination.

[0074] The amount of the conductive auxiliary agent contained in the positive electrode active material layer 220 can be appropriately determined. The positive electrode active material layer 220 contains, for example, 0.01 part by mass or more and 8.0 parts by mass or less of the conductive auxiliary agent with respect to 100 parts by mass of the total mass of the positive electrode active material layer 220.

[0075] The positive electrode active material layer 220 may appropriately contain a pH adjuster (for example, oxalic acid) for neutralizing the alkaline component contained in the positive electrode active material for reasons such as preventing gelation of the slurry.

[0076] The details of the insulating layer 300 will be described. The insulating layer 300 has a fifth surface 312 and a sixth surface 314. The fifth surface 312 of the insulating layer 300 faces the negative electrode 100. The sixth surface 314 of the insulating layer 300 faces the positive electrode 200.

[0077] The insulating layer 300 has a function of electrically insulating the negative electrode 100 and the positive electrode 200 and allowing ions (for example, lithium ions) to pass through.

[0078] The insulating layer 300 is preferably formed on the entire surface 122 of the negative electrode active material layer 120 of the negative electrode 100 facing at least the region where the active material layer of the positive electrode 200 is formed.

[0079] The shape of the insulating layer 300 can be appropriately determined according to the shape of the negative electrode 100 or the positive electrode 200, and can be, for example, rectangular.

[0080] The insulating layer 300 contains at least an insulating substance and a binder. The insulating material contained in the insulating layer 300 includes at least one selected from, for example, aluminum oxide (e.g., α-alumina), silica, acrylic resin, magnesia, calcia, titania, zirconia, boehmite, and magnesium hydroxide. The binder contained in the insulating layer 300 contains at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts.

[0081] The D50 particle size at which the cumulative volume in the particle size distribution of the particle size of the insulating material is 50% is 0.2 μm or more and 0.8 μm or less.

[0082] Among the total weight of the solid materials constituting the insulating layer 300, the weight of the styrene-butadiene rubber contained in the insulating layer 300 is 3% by weight or more and 6% by weight or less.

[0083] The thickness (third direction Z) of the insulating layer 300 can be appropriately determined, and for example, it can be 1.0 μm or more and 45.0 μm or less.

[0084] As shown in FIGS. 3 and 5, in the lithium-ion secondary battery 10, a separator different from the insulating layer 300 formed on the negative electrode active material layer 120 of the negative electrode 100 is not disposed between the positive electrode 200 and the negative electrode 100.

[0085] FIG. 4 is a diagram for explaining an apparatus 500 for manufacturing the negative electrode sheet 100A. FIG. 5 is a diagram for explaining the process of manufacturing the negative electrode sheet 100A by the apparatus 500 shown in FIG. 4.

[0086] In FIG. 4, the apparatus 500 includes a first discharge head 510, a second discharge head 512, a first tank 522, a first pump 524, a first valve 526, a second tank 532, a second pump 534, a second valve 536, a first conveying roller 542, a second conveying roller 544, a third conveying roller 546, and a dryer 550.

[0087] The first discharge head 510 and the second discharge head 512 each have a discharge port 510a and a discharge port 512a. However, the first discharge head 510 and the second discharge head 512 may be constituted by a single discharge head. It is sufficient that a single discharge head has at least the discharge port 510a and the discharge port 512a.

[0088] In FIG. 4, the first conveying roller 542, the second conveying roller 544, and the third conveying roller 546 are rotating in the directions of the arrows (clockwise) respectively attached to the first conveying roller 542, the second conveying roller 544, and the third conveying roller 546. Therefore, the negative electrode current collector sheet 110A is sent from the first conveying roller 542 to the second conveying roller 544 upward from below, and from the second conveying roller 544 to the third conveying roller 546 from left to right.

[0089] Using FIG. 5, the outline of the method for manufacturing the negative electrode sheet 100A according to the present embodiment will be described. This method is (A) A step of applying a negative electrode active material slurry (hereinafter also referred to as the first slurry 120A) containing at least a negative electrode active material and a binder on the first surface 112 of the negative electrode sheet 100A; (B) A step of applying an insulating layer slurry (hereinafter also referred to as the second slurry 130A) containing at least an insulating material and a binder on the surface 122 of the negative electrode active material layer 120 (the first slurry 120A); (C) A step of simultaneously drying the first slurry 120A and the second slurry 130A applied in the above step (A) and the above step (B), and at least including this order.

[0090] First, in step (A), the first slurry 120A spreads wet along the first surface 112 of the negative electrode current collector sheet 110A and is applied to the first surface 112 of the negative electrode current collector sheet 110A (see FIG. 5(a)).

[0091] Next, in step (B), the second slurry 130A spreads along the surface 122 of the negative electrode active material layer 120 formed by the first slurry 120A applied in step (A) and is applied to the surface 122 of the negative electrode active material layer 120 (see Fig. 5(b)).

[0092] As shown in Fig. 5(c), a mixed layer 320 of the negative electrode active material layer 120 (the first slurry 120A) and the insulating layer 300 (the second slurry 130A) is formed at the interface between the negative electrode active material layer 120 and the insulating layer 300. The thickness of this mixed layer 320 is thinner than the thickness of the negative electrode active material layer 120.

[0093] The details of the method according to this embodiment will be described with reference to Figs. 4 and 5.

[0094] The first slurry 120A is stored in the first tank 522. The second slurry 130A is stored in the second tank 532. The first slurry 120A stored in the first tank 522 is supplied to the discharge head 510 via the first pump 524 and the first valve 526. The second slurry 130A stored in the second tank 532 is supplied to the discharge head 510 via the second pump 534 and the second valve 536.

[0095] The first slurry 120A supplied to the discharge head 510 is discharged from the discharge port 510a of the first discharge head 510 toward the first surface 112 of the negative electrode current collector sheet 110A. The pressure of the first slurry 120A discharged onto the first surface 112 of the negative electrode current collector sheet 110A is adjusted by, for example, the first pump 524. The flow rate of the first slurry 120A discharged onto the first surface 112 of the negative electrode current collector sheet 110A is adjusted by, for example, the first valve 526.

[0096] The second slurry 130A supplied to the ejection head 510 is ejected from the ejection port 512a of the second ejection head 512 toward the first surface 112 of the negative electrode current collector sheet 110A. The pressure of the second slurry 130A ejected onto the first surface 112 of the negative electrode current collector sheet 110A is adjusted by, for example, the second pump 534. The flow rate of the second slurry 130A ejected onto the first surface 112 of the negative electrode current collector sheet 110A is adjusted by, for example, the second valve 536.

[0097] In the present embodiment, the first slurry 120A and the second slurry 130A are sequentially ejected from the ejection port 510a of the first ejection head 510 and the ejection port 512a of the second ejection head 512, respectively. Therefore, the second slurry 130A further spreads along the upper surface 122 of the negative electrode active material layer 120 formed by the first slurry 120A that spreads along the first surface 112.

[0098] In the present embodiment, the first slurry 120A and the second slurry 130A are continuously applied in the direction in which the negative electrode current collector sheet 110A is conveyed. For this reason, the first slurry 120A and the second slurry 130A applied to the negative electrode current collector sheet 110A are continuously extended along the direction in which the negative electrode current collector sheet 110A is conveyed.

[0099] In the present embodiment, at least the ejection port 510a of the first ejection head 510 and the ejection port 512a of the second ejection head 512 are provided so as to be aligned in the direction in which the negative electrode current collector sheet 110A is conveyed. The first slurry 120A is ejected from the ejection port 510a of the first ejection head 510, and the second slurry 130A is ejected from the ejection port 512a of the second ejection head 512.

[0100] The interval between the ejection port 510a of the first ejection head 510 and the ejection port 512a of the second ejection head 512 can be set as appropriate.

[0101] The first slurry 120A contains a material that becomes the negative electrode active material layer 120 and a solvent. The solvent contained in the first slurry 120A is, for example, water.

[0102] The second slurry 130A contains a material to be an insulating layer 300 and a solvent. The solvent contained in the second slurry 130A is, for example, water.

[0103] The solid content concentration of the first slurry 120A is 40% or more and 80% or less. The solid content concentration of the second slurry 130A is 20% or more and 80% or less.

[0104] After the first slurry 120A and the second slurry 130A are supplied from the discharge head 510 to the negative electrode current collector sheet 110A, the negative electrode current collector sheet 110A is sent to the dryer 550. Thereby, the first slurry 120A and the second slurry 130A are dried by the dryer 550. The first slurry 120A and the second slurry 130A are respectively formed into the negative electrode active material layer 120 and the insulating layer 300 by the drying of the dryer 550.

[0105] As shown in FIG. 5(c), a mixed layer 320 of the negative electrode active material layer 120 formed by the first slurry 120A and the insulating layer 300 formed by the second slurry 130A is formed at the interface between the negative electrode active material layer 120 and the insulating layer 300. The thickness of this mixed layer 320 is thinner than the thickness of the negative electrode active material layer 120.

[0106] The thickness of the mixed layer 320 is evaluated by the following method. The direction from the surface 122 of the negative electrode active material layer 120 toward the current collector 110 side is defined as the Z direction. Using a scanning electron microscope (SEM), an SEM image of a cross-section of the negative electrode 100 is analyzed. For the image analysis, elemental mapping is performed using an energy dispersive X-ray spectroscopy (EDX) method. The maximum value in the Z direction at which an element that is not detected from the negative electrode active material but is detected from the insulating material is detected is defined as Z A Let it be. The average thickness in the Z direction of the negative electrode active material layer 120 is defined as Z B Let it be. At this time, Z A / Z B is 11% or less.

[0107] Furthermore, the maximum value Z of the thickness in the Z direction A is preferably 35 μm or less, more preferably 25 μm or less.

[0108] According to the present embodiment, the negative electrode 100 has an insulating layer 300 containing at least an insulating material and a binder on the surface 122 of the negative electrode active material layer 120 formed on the first surface 112 of the sheet-like current collector 110. And, in the negative electrode 100 of the present embodiment, the binder contained in the insulating layer 300 contains at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts, and the binder contained in the negative electrode active material layer 120 is at least one selected from polyacrylic acid and its salts. Thereby, a negative electrode 100 in which the negative electrode active material layer 120 and the insulating layer 300 do not mix excessively can be manufactured.

[0109] Also, in the case of the sequential drying method in which the insulating layer 300 is applied after the negative electrode active material layer 120 is coated, dried, and pressed, a thin mixed layer 320 is not formed between the negative electrode active material layer 120 and the insulating layer 300. Therefore, the peeling strength between the negative electrode active material layer 120 and the insulating layer 300 was low, and similarly, it could not be said that the insulating function between the positive electrode and the negative electrode was sufficient.

[0110] Also, in the sequential drying method, due to the unevenness and wrinkles of the coated surface after pressing, the insulating layer 300 cannot be coated uniformly, and due to the gloss of the coated surface, an alliance cannot be achieved. Therefore, there is a possibility that the insulating layer 300 cannot completely cover the negative electrode active material layer 120, or that the insulating layer 300 is coated on a portion where it should not be coated.

[0111] Also, in the method of applying the insulating layer 300 immediately after applying the negative electrode active material layer 120 and drying them simultaneously, if the solvents used in the slurries of the negative electrode active material layer 120 and the insulating layer 300 are not the same, the affinity is low, so the mixed layer 320 is not formed.

[0112] According to the method for manufacturing a negative electrode for a lithium ion secondary battery of the present embodiment, on the negative electrode current collector sheet 110A, (A) a step of applying a negative electrode active material slurry (first slurry 120A) containing at least a negative electrode active material and a binder; (B) a step of applying an insulating layer slurry (second slurry 130A) containing at least an insulating material and a binder on the surface 122 of the negative electrode active material layer 120; (C) a step of simultaneously drying the slurries applied in steps (A) and (B); Since it includes at least these steps in this order, the problems of the above-described sequential coating and drying methods are solved, and when forming the insulating layer 300 on the negative electrode active material layer 120, while enhancing the adhesion between the negative electrode active material layer 120 and the insulating layer 300, it is possible to prevent the insulating performance of the insulating layer 300 from deteriorating.

[0113] Further, in the simultaneous drying method, even if the solvents used in the slurries of the negative electrode active material layer 120 and the insulating layer 300 are the same, if the combination of the binders used in the respective slurries is not appropriate, there is excessive penetration of the insulating layer slurry (second slurry 130A) into the negative electrode active material layer 120. According to the manufacturing method of the present embodiment, by using the binders used in the respective slurries in an appropriate combination, it is possible to prevent excessive penetration of the insulating layer slurry (second slurry 130A) into the negative electrode active material layer 120 and prevent the insulating performance of the insulating layer from deteriorating.

[0114] According to the present embodiment, the thickness of the mixed layer 320 formed at the interface between the negative electrode active material layer 120 and the insulating layer 300 is thinner than the thickness of the negative electrode active material layer 120. Thus, according to the present embodiment, excessive penetration of the second slurry 130A for forming the insulating layer 300 into the negative electrode active material layer 120 can be prevented. Further, since excessive penetration of the first slurry 120A for forming the negative electrode active material layer 120 into the insulating layer 300 can also be prevented, the active material does not expose on the surface of the insulating layer 300 and the insulating function is not impaired. Thereby, the insulating functions of the positive and negative electrodes of the lithium ion secondary battery can be appropriately maintained.

[0115] According to the present embodiment, the maximum depth Z at which the insulating substance is detected in the negative electrode active material layer 120 A is such that when the average thickness in the Z direction of the negative electrode active material layer is Z B and Z A / Z B is 11% or less, so that the diffusion of the insulating substance into the negative electrode active material layer 120 does not become excessive.

[0116] According to the present embodiment, the particle size of the insulating substance is limited to 0.2 μm or more and 0.8 μm or less. Thereby, it is possible to prevent the problem that the coating is not achieved when the particle size of the insulating substance is too small, and the problem that the number of particles with respect to the film thickness decreases and the insulating property deteriorates when the particle size is too large. That is, it is possible to promote a suitable coating and maintain an appropriate insulating property because the particles are contained in an appropriate ratio with respect to the film thickness.

[0117] According to the present embodiment, by restricting the amount of the binder of the insulating layer 300, it is possible to solve the problem that the adhesion deteriorates when the amount of the binder is too small. Further, when the amount of the binder is large, it is possible to solve the problem that the voids in the insulating layer become small, the movement of the lithium salt between the positive and negative electrodes is inhibited, and the resistance of the battery increases.

[0118] According to this embodiment, by restricting the amount of the binder in the negative electrode active material layer 120, a sufficient amount of the negative electrode active material is ensured, and since there is no excessive presence of a binder with high electrical resistance, an effect that a high-capacity and high-output electrode can be obtained is achieved.

[0119] According to this embodiment, since the insulating layer 300 having the function of a separator is formed on the negative electrode active material layer 120, a separator disposed between the positive electrode 200 and the negative electrode 100 becomes unnecessary. Thereby, the lithium ion secondary battery can be made thinner and a short circuit between the positive electrode and the negative electrode of the lithium ion secondary battery can be prevented.

[0120] As described above, the embodiments of the present invention have been described with reference to the drawings, but these are examples of the present invention, and various configurations other than the above can also be adopted. For example, in the above embodiment, the battery cell has been described as having a configuration including an electrolytic solution. An electrolyte in a gel form can also be manufactured by the same process as the embodiment. On the other hand, in the case of an all-solid-state battery in which the electrolyte is solid, the manufacturing method of the negative electrode 100 is as described below.

[0121] In step (A), a negative electrode active material slurry (first slurry 120A) containing at least a negative electrode active material, a binder, and a solid electrolyte is applied. The solid electrolyte is, for example, Li7La3Zr2O 12 (LLZ). In step (B), a high-resistance layer slurry (second slurry 130A) containing at least a solid electrolyte and a binder is applied onto the surface 122 of the negative electrode active material layer 120. The solid electrolyte is, for example, Li7La3Zr2O 12 (LLZ). Then, in step (C), the slurries applied in steps (A) and (B) are dried simultaneously.

[0122] As described above, in the case of non-all-solid-state batteries, the insulating material contained in the insulating layer 300 includes, for example, at least one selected from aluminum oxide (e.g., α-aluminum oxide), silica, acrylic resin, magnesia, calcia, titania, zirconia, boehmite, and magnesium hydroxide. On the other hand, in the case of all-solid-state batteries, the high-resistance layer (high-resistance layer slurry) is a solid electrolyte, and the insulating material contained in the above-described insulating layer 300 does not necessarily have to be included. That is, in the case of all-solid-state batteries, the high-resistance layer (high-resistance layer slurry) only needs to contain at least a solid electrolyte.

Example

[0123] Table 1 shows the production conditions and evaluation results of the negative electrode 100 of Examples 1 to 11. The details of the production conditions of the samples will be described below.

Table 1

[0124] <Production method and conditions> As the negative electrode active material constituting the negative electrode active material layer 120, natural graphite coated with amorphous graphite manufactured by Hitachi Chemical Co., Ltd. was used. The negative electrode active material layer 120 contains a conductive assistant, and carbon black was used as the conductive assistant. In all examples and comparative examples, carbon black C65 was 0.4% by weight of the total weight of the solid materials constituting the negative electrode active material layer 120.

[0125] As the binder constituting the negative electrode active material layer 120, Aquacharge manufactured by Sumitomo Seika Chemical Co., Ltd. was used as polyacrylic acid (PAA: Polyacrylic Acid).

[0126] As the insulating material (filler) constituting the insulating layer 300, any one of alumina, acrylic resin (polymethyl methacrylate resin (PMMA)), and silica was used. As the alumina, alumina AKP-3000 manufactured by Sumitomo Chemical Co., Ltd. was used. As the acrylic resin (PMMA), the product number (grade) MX-80H3wT (average particle diameter 0.8 μm, degree of crosslinking: high) of the crosslinked acrylic monodisperse particle MX series manufactured by Soken Chemical & Engineering Co., Ltd. was used. As the silica, SFP-20M (0.3 μm) or SFP-30M (0.6 μm) of Super Fine Powder (submicron silica) manufactured by Denka Co., Ltd. was used.

[0127] As the binder constituting the insulating layer 300, a mixture of sodium carboxymethyl cellulose (CMC-Na) and styrene-butadiene rubber (SBR) was used. As the CMC, MAC-350HC of the MAC series of Sunrose (registered trademark) manufactured by Nippon Paper Industries Co., Ltd. was used. As the SBR, BM-451B manufactured by Nippon Zeon Co., Ltd. was used.

[0128] Each slurry viscosity was 8000 ± 2000 mPa·s (conditions: B-type viscometer, 20 °C, shear rate 2.04 s-1). Simultaneous coating was performed using the two first discharge heads 510 and second discharge heads 512 of FIG. 4. Simultaneous coating will be described later. The basis weight was 11 mg / cm for the negative electrode active material layer 120 2 and 2 mg / cm for the insulating layer 300 2 However, as shown in each table, samples with the basis weight of the insulating layer 300 changed were prepared for some of the examples and comparative examples.

[0129] <Evaluation method> The negative electrode 100 prepared by the following method was evaluated. (1) Conductivity confirmation by tester This was performed on the samples of Examples 1 to 11 and Comparative Examples 1 to 14. The results are shown in Tables 1 and 2. (2) Photograph the surface of the electrode and measure the whiteness This was done for the samples of Example 1, Comparative Examples 1, 5, and 9. The results will be described later.

[0130] (3) Cross-section observation Using a scanning electron microscope (SEM), analyze the SEM image of the cross-section of the negative electrode 100. For the image analysis, perform elemental mapping using energy dispersive X-ray spectroscopy (EDX). This was done for the samples of Example 1, Comparative Examples 1, 5, and 9. The results will be described later with reference to FIGS. 6 and 7.

[0131] (4) Evaluation of the interfacial peeling strength between simultaneous coating and sequential coating Using the material of the sample of Example 1, compare the sample produced by the simultaneous coating of the present invention with the sample produced by sequential coating. The results will be described later.

[0132] In simultaneous coating, the slurries applied in the following steps (A) and (B) were dried simultaneously. Here, the coating steps (A) and (B) are performed sequentially, and drying two types of slurries simultaneously is called simultaneous coating. In sequential coating, after the following step (A), the slurry applied in step (A) is dried, then the following step (B) is performed, and the slurry applied in step (B) is dried. (A) Step of applying a negative electrode active material slurry containing at least a negative electrode active material and a binder (B) Step of applying an insulating layer slurry containing at least an insulating material and a binder on the surface of the negative electrode active material layer

[0133] <Evaluation results> (1) Conductivity confirmation by a tester The tester used a digital multimeter (CDM-2000) manufactured by Custom Co., Ltd. The resistance range was measured at 30 MΩ. The negative electrode sheet 100A includes a copper foil (current collector sheet), a negative electrode active material layer 120, and an insulating layer 300. The method for confirming conductivity was to place the tip of the test lead of the tester on the front and back surfaces of a 10 cm square sample, and if it was the measurement limit (open range), it was regarded as "insulated". Conductivity confirmation was performed on 10 samples, and the ratio of the number of insulated samples (the number of samples where conductivity could not be obtained) was calculated. If all 10 samples were insulated, it was 100%.

[0134] As a result of the conductivity confirmation, in any of Examples 1 to 11, the insulation rate was 100%. In other words, in any of Examples 1 to 11, it indicates that good insulation was obtained for all 10 samples.

[0135] In any of Examples 1 to 11, the binder contained in the insulating layer 300 at least included styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts, and the binder contained in the negative electrode active material layer 120 was at least one selected from polyacrylic acid and its salts. Specifically, in Examples 1 to 11, the binder contained in the insulating layer 300 used a mixture of CMC and SBR, and the binder contained in the negative electrode active material layer 120 used PAA.

[0136] In any of Examples 1 to 11, the D50 particle size at which the cumulative volume in the particle size distribution of the insulating substance constituting the insulating layer 300 was 50% was in the range of 0.2 μm or more and 0.8 μm or less. Specifically, Example 10 used 0.3 μm (small), Example 11 used 0.6 μm (large), Examples 1 to 8 used 0.7 μm (large), and Example 9 used 0.8 μm (large). No influence of the D50 particle size of the insulating substance on the insulation rate was observed.

[0137] In all of Examples 1 to 11, among the total weight of the solid materials constituting the insulating layer 300, the weight of SBR contained in the insulating layer 300 was 3% by weight or more and 6% by weight or less. Specifically, in Examples 1 to 3, 6 to 8, and 11, it was 3% by weight, in Examples 4 to 5 and 10, it was 4% by weight, and in Example 9, it was 6% by weight. Also, the total content of CMC and SBR of the binder of the insulating layer 300 was 7% by weight in Examples 1 to 2, 6 to 8, and 10, 6% by weight in Examples 3 and 11, 9% by weight in Example 4, 10% by weight in Example 5, and 12% by weight in Example 9. No influence on the insulation rate was observed due to the total content of CMC and SBR of the binder of the insulating layer 300.

[0138] In all of Examples 1 to 11, among the total weight of the solid materials constituting the negative electrode active material layer 120, the total weight of polyacrylic acid and its salts of the binder contained in the negative electrode active material layer 120 was 3% by weight or more and 6% by weight or less. Specifically, the weight of PAA of the binder was 3% by weight in Examples 1 to 6, 9 to 11, 4% by weight in Example 7, and 6% by weight in Example 8. This is included within the range of 3% by weight or more and 6% by weight or less. No influence on the insulation rate was observed due to the content of PAA of the binder of the negative electrode active material layer 120.

[0139] In all of Examples 1 to 11, the insulating substance constituting the insulating layer 300 contained at least one selected from alumina, silica, acrylic resin, magnesia, calcia, titania, zirconia, boehmite, and magnesium hydroxide. Specifically, alumina was used in Examples 1 to 8, acrylic resin was used in Example 9, and silica was used in Examples 10 to 11.

[0140] Taking Example 1 as the standard condition, as shown in Table 1, each example changed the following conditions. In Example 2, the basis weight of the insulating layer 300 of Example 1 was 2.0 mg / cm 2 and it was made larger to 2.6 mg / cm 2 . No influence on the insulation rate was observed due to the basis weight of the insulating layer 300.

[0141] In Examples 6 to 8, silica was added to the negative electrode active material, and the content of PAA in the binder was changed. In Example 6, out of the total weight of the solid materials constituting the negative electrode active material layer 120, silica was 2.9% by weight (small), PAA was 3% by weight, in Example 7, silica was 9.6% by weight (medium), PAA was 4% by weight, and in Example 8, silica was 37.4% by weight (large), PAA was 6% by weight. The content of PAA was 3% by weight or more and 6% by weight or less. Even when silica was added to the negative electrode active material, no influence on the insulation rate was observed.

[0142] (Comparative Example) Table 2 shows the production conditions and evaluation results of the negative electrode 100 of Comparative Examples 1 to 14.

Table 2

[0143] In Comparative Examples 1 to 3, the binder contained in the insulating layer 300 did not contain at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts, and PAA was used. Note that the binder contained in the negative electrode active material layer 120 used PAA. Comparative Example 2 increased the basis weight of the insulating layer 300 to 2.6 mg / cm 2 which was larger than that of Comparative Example 1. Comparative Example 3 increased the mixing ratio of PAA in the binder contained in the insulating layer 300 compared to Comparative Example 1. Comparative Example 4 added silica to the graphite of Example 1 as the negative electrode active material, and among the total weight of the solid materials constituting the negative electrode active material layer 120, the weight of PAA in the binder contained in the negative electrode active material layer 120 was increased to 4% by weight, which was more than that of Comparative Example 1.

[0144] The results of the conduction confirmation for Comparative Examples 1 to 4 showed an insulation rate of 20%. That is, Comparative Examples 1 to 4 indicate that among the 10 samples, insulation was obtained for 2 samples, but good insulation was not obtained for 8 samples. In other words, in Comparative Examples 1 to 4 that do not contain at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts in the binder contained in the insulating layer 300, good insulation was not obtained. Also, even when increasing the basis weight of the insulating layer 300 (Comparative Example 2), even when increasing the mixing ratio of PAA in the binder (binder) contained in the insulating layer 300 (Comparative Example 3), even when adding silica to the negative electrode active material (Comparative Example 4), or even when increasing the mixing ratio of PAA in the binder of the negative electrode active material layer 120 (Comparative Example 4), the insulation was 20% and was not affected by these conditions.

[0145] In Comparative Examples 5 to 8, CMC and SBR were used, where the binder contained in the negative electrode active material layer 120 is not at least one selected from polyacrylic acid and its salts. Comparative Example 6 had a basis weight of the insulating layer 300 of 2.6 mg / cm 2 which was larger than that of Comparative Example 5. Comparative Example 7 increased the mixing ratio of CMC and SBR in the binder of the negative electrode active material layer 120 compared to Comparative Example 5. Comparative Example 7 increased the total weight of CMC and SBR in the binder contained in the negative electrode active material layer 120 to 4% by weight, which was more than that of Comparative Example 5, out of the total weight of the solid materials constituting the negative electrode active material layer 120. Comparative Example 8 added silica to the graphite of Comparative Example 5 as the negative electrode active material, and Mixing ratio of CMC and SBR increased the amount of the binder contained in the negative electrode active material layer 120 to 4% by weight, which was more than that of Comparative Example 5, out of the total weight of the solid materials constituting the negative electrode active material layer 120.

[0146] The results of the conduction confirmation for Comparative Examples 5 to 8 showed an insulation rate of 0%. That is, Comparative Examples 5 to 8This indicates that good insulation could not be obtained for all 10 samples. In other words, in Comparative Examples 5 to 8 where the binder in the negative electrode active material layer is not at least one selected from polyacrylic acid and its salts, and the binder in the insulating layer 300 does not contain at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts, good insulation could not be obtained. Also, even when the basis weight of the insulating layer 300 was increased (Comparative Example 6), even when the mixing ratio of CMC and SBR in the binder of the negative electrode active material layer was increased (Comparative Examples 7 and 8), and even when silica was added to the negative electrode active material (Comparative Example 8), the insulation was 0% and was not affected by these conditions.

[0147] In Comparative Examples 9 to 11, CMC and SBR were used as the binders for both the negative electrode active material layer 120 and the insulating layer 300. In Comparative Example 10, the basis weight of the insulating layer 300 was made larger than that in Comparative Example 9 by 2.6 mg / cm 2 . In Comparative Example 11, the mixing ratio of CMC and SBR in the binder of the negative electrode active material layer 120 was made larger than that in Comparative Example 9.

[0148] The results of the conduction confirmation in Comparative Examples 9 to 11 showed that the insulation rate was 0%. That is, Comparative Examples 9 to 11 indicate that good insulation could not be obtained for all 10 samples. In other words, in Comparative Examples 9 to 11 where the binder contained in the negative electrode active material layer 120 is not at least one selected from polyacrylic acid and its salts, good insulation could not be obtained. Also, even when the basis weight of the insulating layer 300 was increased (Comparative Example 10), even when the mixing ratio of CMC and SBR in the binder of the negative electrode active material layer 120 was increased (Comparative Example 11), the insulation was 0% and was not affected by these conditions.

[0149] In Comparative Examples 12 to 14, the insulating material constituting the insulating layer 300 was an acrylic resin. In Comparative Example 12, the binders for both the negative electrode active material layer 120 and the insulating layer 300 were PAA. In Comparative Example 13, the binder for the negative electrode active material layer 120 was CMC and SBR, and the binder for the insulating layer 300 was PAA. In Comparative Example 14, the binders for both the negative electrode active material layer 120 and the insulating layer 300 were CMC and SBR.

[0150] The results of the conduction confirmation of Comparative Example 12 were an insulation rate of 10%, and the insulation rates of Comparative Examples 13 and 14 were 0%. That is, even when an acrylic resin was used for the insulating layer 300, the binder contained in the negative electrode active material layer was not at least one selected from polyacrylic acid and its salts, and the binder contained in the insulating layer 300 was styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts. In Comparative Examples 5 to 8 that did not contain at least these, good insulation properties could not be obtained.

[0151] (2) Photograph the electrode surface and measure the whiteness The results obtained for the samples of Example 1, Comparative Examples 1, 5, and 9 were as shown in Table 3 below.

Table 3

[0152] The whiteness when only the negative electrode active material layer 120 was present was 11.7, and the whiteness when only the insulating layer 300 was present was 79.7. That is, in Comparative Example 5, it can be seen that the insulating layer 300 almost penetrated into the negative electrode active material layer 120 and the whiteness was almost the same as that when only the negative electrode active material layer 120 was present. In Comparative Example 5, the insulation rate was also 0%.

[0153] It can be seen that in Comparative Example 1 and Comparative Example 9, a certain degree of the insulating layer 300 penetrated into the negative electrode active material layer 120, and the value was lower than the whiteness when only the insulating layer 300 was present. In Comparative Example 1 and Comparative Example 9, the insulation rates were also as low as 0 to 20%.

[0154] In Example 1, the value was slightly lower than the whiteness when only the insulating layer 300 was present, and the insulation rate was 100%. That is, it can be seen that while maintaining the insulation properties, a certain amount of the insulating layer 300 penetrated into the negative electrode active material layer 120.

[0155] (3) Cross-section observation Figures 6 and 7 show the cross-sectional results of the samples of Example 1, Comparative Examples 1, 5, and 9. The SEM images and the elemental mapping images using the EDX method are arranged in the left-right order. The upper image in Figure 6 is the sample of Example 1, the lower image in Figure 6 is the sample of Comparative Example 9, the upper image in Figure 7 is the sample of Comparative Example 1, and the lower image in Figure 7 is the sample of Comparative Example 5.

[0156] In the SEM images of each figure, the uppermost layer is the insulating layer 300, the lowermost layer is the negative electrode current collector 110, and the center is the negative electrode active material layer 120. Looking at the elemental mapping image using the EDX method in the upper part of Figure 6, it can be seen that at the interface between the insulating layer 300 and the negative electrode active material layer 120 of the sample of Example 1, the penetration of the second slurry 130A constituting the insulating layer 300 into the negative electrode active material layer 120 is the least. Apparently, a mixed layer 320 of the negative electrode active material layer 120 and the insulating layer 300, which is thinner than the thickness of the negative electrode active material layer 120, is formed at the interface between the negative electrode active material layer 120 and the insulating layer 300.

[0157] Furthermore, the above-mentioned Z A / Z B was 6.1% and was 11% or less. Z A was 6.3 μm. The insulation rate of the sample of Example 1 was 100%.

[0158] Looking at the elemental mapping image using the EDX method in the lower part of Figure 7, it can be seen that at the interface between the insulating layer 300 and the negative electrode active material layer 120 of the sample of Comparative Example 9, the penetration of the second slurry 130A constituting the insulating layer 300 into the negative electrode active material layer 120 is the most. The above-mentioned Z A / Z B was 79% and was 11% or more. The insulation rate of the sample of Comparative Example 9 was 0%.

[0159] Looking at the elemental mapping image using the EDX method in Fig. 7, it can be seen that in the sample of Comparative Example 1 (upper side of Fig. 7), penetration of the second slurry 130A constituting the insulating layer 300 into the negative electrode active material layer 120 is less at the interface between the insulating layer 300 and the negative electrode active material layer 120 than in the sample of Comparative Example 5 (lower side of Fig. 7). The above-mentioned Z A / Z B was 44% and 36% respectively, and both were 11% or more. The insulation rate of the sample of Comparative Example 1 is 20%, which is higher than the insulation rate of 0% of the sample of Comparative Example 5.

[0160] (4) Evaluation of the interfacial peeling strength of simultaneous coating and sequential coating After attaching the tape to the surface of the insulating layer 300 of the negative electrode sheet 100A of the sample, it was pulled and peeled in a direction of 180 degrees with respect to the sheet surface. In the sample of simultaneous coating, only a small amount of powder on the surface of the insulating layer 300 adhered to the tape. In the sample of sequential coating, the insulating layer 300 peeled off from the interface between the insulating layer 300 and the negative electrode active material layer 120 was transferred to the tape in a striped pattern. From this result, it can be seen that the interfacial peeling strength is stronger in the sample produced by simultaneous coating than in the sample produced by sequential coating, and hardly peels off.

[0161] As described above, the present invention has been described with reference to the embodiments and examples, but the present invention is not limited to the above embodiments and examples. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

[0162] Examples of reference embodiments are appended below. 1. On a current collector, A negative electrode for a lithium-ion secondary battery in which a negative electrode active material layer containing at least a negative electrode active material and a binder is formed, Further having an insulating layer containing at least an insulating substance and a binder on the surface of the negative electrode active material layer, The binder contained in the insulating layer contains at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts. The binder contained in the negative electrode active material layer is at least one selected from polyacrylic acid and its salts, and is a negative electrode for a lithium ion secondary battery. 2. At the interface between the negative electrode active material layer and the insulating layer, a mixed layer of the negative electrode active material layer and the insulating layer, which is thinner than the thickness of the negative electrode active material layer, is formed. said A negative electrode for a lithium ion secondary battery according to 1. 1. The negative electrode for a lithium ion secondary battery according to 1. 3. When performing elemental mapping using the EDX method in the cross-sectional SEM image of the cross-section of the negative electrode, the direction from the surface of the negative electrode active material layer on the side not in contact with the current collector toward the current collector side is defined as the Z direction. An element that is not detected from the negative electrode active material but is detected from the insulating material is detected in the Z direction. of the thickness The maximum value is Z A And the average thickness of the negative electrode active material layer in the Z direction is Z B When it is A / Z B Is 11% or less. A negative electrode for a lithium ion secondary battery according to 1. or 2. 4. The maximum value Z of the thickness in the Z direction A Is 35 μm or less. A negative electrode for a lithium ion secondary battery according to 3. 5. The D50 particle size at which the cumulative volume in the particle size distribution of the particle size of the insulating material is 50% is 0.2 μm or more and 0.8 μm or less. A negative electrode for a lithium ion secondary battery according to any one of 1. to 4. 6. Among the total weight of the solid material constituting the insulating layer, the weight of styrene-butadiene rubber contained in the insulating layer is 3% by weight or more and 6% by weight or less. A negative electrode for a lithium ion secondary battery according to any one of 1. to 5. 7. Among the total weight of the solid materials constituting the negative electrode active material layer, the total weight of polyacrylic acid and its salts among the binder materials contained in the negative electrode active material layer is 3% by weight or more and 6% by weight or less. 1. The negative electrode for a lithium ion secondary battery according to any one of 1. to 6. 8. The insulating material contains at least one selected from alumina, silica, acrylic resin, magnesia, calcia, titania, zirconia, boehmite, and magnesium hydroxide. 1. The negative electrode for a lithium ion secondary battery according to any one of 1. to 7.

[0163] 9. A lithium ion secondary battery including a positive electrode having a positive electrode active material layer formed on a current collector, a negative electrode, and an electrolyte, wherein the negative electrode is the negative electrode according to any one of 1. to 8. Lithium ion secondary battery. 10. The insulating layer is at least on the said positive electrode entire surface of the negative electrode active material layer of the negative electrode facing the region where the active material layer is formed. 18. The lithium ion secondary battery according to 9. 11. A separator different from the insulating layer formed on the negative electrode active material layer of the negative electrode is not disposed between the positive electrode and the negative electrode. 11. The lithium ion secondary battery according to 9. or 10.

[0164] 12. On a sheet-like current collector, (A) A step of applying a negative electrode active material slurry containing at least a negative electrode active material and a binder; (B) A step of applying an insulating layer slurry containing at least an insulating material and a binder on the surface of the negative electrode active material slurry; (C) A step of simultaneously drying the slurries applied in the steps (A) and (B); A method for manufacturing a negative electrode for a lithium ion secondary battery including at least these steps in this order. The binder contained in the insulating layer slurry contains at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts. A method for manufacturing a negative electrode for a lithium-ion secondary battery, wherein the binder contained in the negative electrode active material slurry is at least one selected from polyacrylic acid and its salts. 13. A method for manufacturing a negative electrode sheet for a lithium-ion secondary battery for manufacturing a negative electrode for a lithium-ion secondary battery by the manufacturing method according to 12., A method for manufacturing a negative electrode sheet for a lithium-ion secondary battery, wherein a negative electrode active material slurry containing at least a negative electrode active material and a binder and an insulating layer slurry containing at least an insulating material and a binder are continuously applied in the direction in which the current collector sheet is continuously conveyed. 14. Using a discharge head having at least a first discharge port and a second discharge port arranged in the direction in which the current collector sheet is conveyed, discharging the negative electrode active material slurry from the first discharge port and discharging the insulating layer slurry from the second discharge port. The method for manufacturing a negative electrode sheet for a lithium-ion secondary battery according to 13. 15. The solid content concentration of the negative electrode active material slurry is 40% or more and 80% or less, and the solid content concentration of the insulating layer slurry is 20% or more and 80% or less. The method for manufacturing a negative electrode sheet for a lithium-ion secondary battery according to 13. or 14. 16. The viscosity of the negative electrode active material slurry at a shear rate of 2.04 s-1 at 20 °C measured by a B-type viscometer is 6 Pa·S or more and 10 Pa·S or less, and the viscosity of the insulating layer slurry at a shear rate of 2.04 s-1 at 20 °C measured by a B-type viscometer is 6 Pa·S or more and 10 Pa·S or less. The method for manufacturing a negative electrode sheet for a lithium-ion secondary battery according to 15. 17. The D50 particle size at which the cumulative volume in the particle size distribution of the particle size of the insulating material contained in the insulating layer slurry is 50% is 0.2 μm or more and 0.8 μm or less. The method for manufacturing a negative electrode sheet for a lithium-ion secondary battery according to any one of 13. to 16. 18. Among the total weight of the solid materials constituting the insulating layer formed by the insulating layer slurry, the total weight of styrene-butadiene rubber contained in the insulating layer is 3% by weight or more and 6% by weight or less. 13. The method for manufacturing a negative electrode sheet for a lithium ion secondary battery according to any one of 13. to 17. 19. Among the total weight of the solid materials constituting the negative electrode active material layer formed by the negative electrode active material slurry, the total weight of polyacrylic acid and its salts, which are the binder materials contained in the negative electrode active material layer, is 3% by weight or more and 6% by weight or less. 13. The method for manufacturing a negative electrode sheet for a lithium ion secondary battery according to any one of 13. to 18. 20. The insulating substance contains at least one selected from alumina, silica, acrylic resin, magnesia, calcia, titania, zirconia, boehmite, and magnesium hydroxide. 13. The method for manufacturing a negative electrode sheet for a lithium ion secondary battery according to any one of 13. to 19.

[0165] 21. On the current collector, A negative electrode for a lithium ion secondary battery in which a negative electrode active material layer containing at least a negative electrode active material and a binder is formed, On the surface of the negative electrode active material layer, there is further a high-resistance layer containing at least a solid electrolyte and a binder, The binder contained in the high-resistance layer contains at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts, The binder contained in the negative electrode active material layer is at least one selected from polyacrylic acid and its salts. A negative electrode for an all-solid-state lithium ion secondary battery. 22. At the interface between the negative electrode active material layer and the high-resistance layer, a mixed layer of the negative electrode active material layer and the high-resistance layer that is thinner than the thickness of the negative electrode active material layer is formed. said The negative electrode for an all-solid-state lithium ion secondary battery according to 21. 21. 23. When performing elemental mapping using the EDX method on a cross-sectional SEM image of the negative electrode, with the direction from the surface of the negative electrode active material layer on the side not in contact with the current collector toward the current collector side defined as the Z direction, the maximum value in the Z direction of an element that is not detected from the negative electrode active material but is detected from the solid electrolyte is Z of the thickness and the average thickness in the Z direction of the negative electrode active material layer is Z A When, B Z A / Z B is 11% or less, The negative electrode for an all-solid-state lithium-ion secondary battery according to 21. or 22. 24. The maximum value Z of the thickness in the Z direction A is 35 μm or less, The negative electrode for an all-solid-state lithium-ion secondary battery according to 23. 25. The D50 particle size at which the cumulative volume in the particle size distribution of the particle size of the solid electrolyte is 50% is 0.2 μm or more and 0.8 μm or less, The negative electrode for an all-solid-state lithium-ion secondary battery according to any one of 21. to 24. 26. Among the total weight of the solid material constituting the high-resistance layer, the weight of styrene-butadiene rubber contained in the high-resistance layer is 3% by weight or more and 6% by weight or less, The negative electrode for an all-solid-state lithium-ion secondary battery according to any one of 21. to 25. 27. Among the total weight of the solid material constituting the negative electrode active material layer, the total weight of polyacrylic acid and its salts as the binder contained in the negative electrode active material layer is 3% by weight or more and 6% by weight or less, The negative electrode for an all-solid-state lithium-ion secondary battery according to any one of 21. to 26. 28. An all-solid-state lithium-ion secondary battery including a positive electrode with a positive electrode active material layer formed on a current collector, a negative electrode, and a solid electrolyte, wherein the negative electrode is the negative electrode according to any one of 21. to 27., All-solid-state lithium-ion secondary battery.

[0166] 29. On a sheet-like current collector, (A) A step of applying a negative electrode active material slurry containing at least a negative electrode active material and a binder; (B) A step of applying a high-resistance layer slurry containing at least a solid electrolyte and a binder on the surface of the negative electrode active material slurry; (C) A step of simultaneously drying the slurries applied in the step (A) and the step (B); A method for manufacturing a negative electrode for an all-solid-state lithium-ion secondary battery, including at least these steps in this order, The binder contained in the high-resistance layer slurry contains at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts, The binder contained in the negative electrode active material slurry is at least one selected from polyacrylic acid and its salts. A method for manufacturing a negative electrode for an all-solid-state lithium-ion secondary battery. 30. A method for manufacturing a negative electrode sheet for an all-solid-state lithium-ion secondary battery for manufacturing a negative electrode for an all-solid-state lithium-ion secondary battery by the manufacturing method according to 29., A negative electrode active material slurry containing at least a negative electrode active material and a binder, and a high-resistance layer slurry containing at least a solid electrolyte and a binder are continuously applied in the direction in which the current collector sheet is continuously conveyed. A method for manufacturing a negative electrode sheet for an all-solid-state lithium-ion secondary battery.

Explanation of symbols

[0167] 10 Lithium-ion secondary battery 12 Laminate 150 First lead 250 Second lead 400 Exterior material 100 Negative electrode 100A Negative electrode sheet 110 Negative electrode current collector 110A Negative electrode current collector sheet 112 First surface 114 Second surface 120 Negative electrode active material layer 122 Surface 200 Positive electrode 210 Positive current collector 212 Third surface 214 Fourth surface 220 Positive active material layer 300 Insulating layer 312 Fifth surface 314 Sixth surface 320 Mixed layer 120A First slurry 130A Second slurry 500 Device 510 First discharge head 510a Discharge port 512 Second discharge head 512a Discharge port 522 First tank 524 First pump 526 First valve 532 Second tank 534 Second pump 536 Second valve 542 First conveying roller 544 Second conveying roller 546 Third conveying roller 550 Dryer

Claims

1. On one surface of a current collector, A negative electrode for a lithium-ion secondary battery having a negative electrode active material layer formed thereon, which contains at least a negative electrode active material and a binder, Further having an insulating layer containing at least an insulating material and a binder on a first surface, which is a surface of the negative electrode active material layer opposite to the current collector, The binder contained in the insulating layer contains at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts, The binder contained in the negative electrode active material layer is at least one selected from polyacrylic acid and its salts, A negative electrode for a lithium-ion secondary battery, in which a mixed layer of the negative electrode active material layer and the insulating layer, which is thinner than the thickness of the negative electrode active material layer, is formed at an interface between the negative electrode active material layer and the insulating layer.

2. The D50 particle size at which the cumulative volume in the particle size distribution of the particle size of the insulating material is 50% is 0.2 μm or more and 0.8 μm or less, The negative electrode for a lithium-ion secondary battery according to Claim 1.

3. Among the total weight of the solid materials constituting the insulating layer, the weight of styrene-butadiene rubber contained in the insulating layer is 3% by weight or more and 6% by weight or less, The negative electrode for a lithium-ion secondary battery according to Claim 1 or 2.

4. Among the total weight of the solid materials constituting the negative electrode active material layer, the total weight of polyacrylic acid and its salts among the binders of polyacrylic acid and its salts contained in the negative electrode active material layer is 3% by weight or more and 6% by weight or less, The negative electrode for a lithium-ion secondary battery according to any one of Claims 1 to 3.

5. The insulating material contains at least one selected from alumina, silica, acrylic resin, magnesia, calcia, titania, zirconia, boehmite, and magnesium hydroxide, The negative electrode for a lithium ion secondary battery according to any one of claims 1 to 4.

6. A lithium ion secondary battery including a positive electrode electrode having a positive electrode active material layer formed on a current collector, a negative electrode, and an electrolyte, wherein the negative electrode is the negative electrode according to any one of claims 1 to 5. Lithium ion secondary battery.

7. The insulating layer is formed on the entire surface of the first surface. The lithium ion secondary battery according to claim 6.

8. A separator different from the insulating layer formed on the negative electrode active material layer of the negative electrode is not disposed between the positive electrode and the negative electrode. The lithium ion secondary battery according to claim 6 or 7.

9. On a sheet-like current collector (A) A step of applying a negative electrode active material slurry containing at least a negative electrode active material and a binder; (B) A step of applying an insulating layer slurry containing at least an insulating substance and a binder on the surface of the negative electrode active material slurry; (C) A step of simultaneously drying the slurries applied in the step (A) and the step (B); A method for manufacturing a negative electrode for a lithium ion secondary battery, including at least in this order: The binder contained in the insulating layer slurry contains at least styrene butadiene rubber and at least one selected from carboxymethyl cellulose and its salts. The binder contained in the negative electrode active material slurry is at least one selected from polyacrylic acid and its salts. A method for manufacturing a negative electrode for a lithium ion secondary battery.

10. A method for manufacturing a negative electrode sheet for a lithium ion secondary battery for manufacturing a negative electrode for a lithium ion secondary battery by the manufacturing method according to claim 9. A method for manufacturing a negative electrode sheet for a lithium-ion secondary battery, wherein a negative electrode active material slurry containing at least a negative electrode active material and a binder, and an insulating layer slurry containing at least an insulating material and a binder are continuously applied in a direction in which a current collector sheet is continuously conveyed.

11. Using a discharge head having at least a first discharge port and a second discharge port arranged in the direction in which the current collector sheet is conveyed, the negative electrode active material slurry is discharged from the first discharge port, and the insulating layer slurry is discharged from the second discharge port. The method for manufacturing a negative electrode sheet for a lithium-ion secondary battery according to claim 10.

12. The solid content concentration of the negative electrode active material slurry is 40% or more and 80% or less, and the solid content concentration of the insulating layer slurry is 20% or more and 80% or less. The method for manufacturing a negative electrode sheet for a lithium-ion secondary battery according to claim 10 or 11.

13. The viscosity of the negative electrode active material slurry at a shear rate of 2.04 s-1 at 20 °C measured by a B-type viscometer is 6 Pa·S or more and 10 Pa·S or less, and the viscosity of the insulating layer slurry at a shear rate of 2.04 s-1 at 20 °C measured by a B-type viscometer is 6 Pa·S or more and 10 Pa·S or less. The method for manufacturing a negative electrode sheet for a lithium-ion secondary battery according to claim 12.

14. The D50 particle size at which the cumulative volume in the particle size distribution of the particle size of the insulating material contained in the insulating layer slurry is 50% is 0.2 μm or more and 0.8 μm or less. The method for manufacturing a negative electrode sheet for a lithium-ion secondary battery according to any one of claims 10 to 13.

15. Among the total weight of the solid materials constituting the insulating layer formed by the insulating layer slurry, the total weight of the styrene-butadiene rubber contained in the insulating layer is 3% by weight or more and 6% by weight or less. The method for manufacturing a negative electrode sheet for a lithium-ion secondary battery according to any one of claims 10 to 14.

16. Among the total weight of the solid materials constituting the negative electrode active material layer formed by the negative electrode active material slurry, the total weight of polyacrylic acid and its salts among the binders contained in the negative electrode active material layer is 3% by weight or more and 6% by weight or less. A method for manufacturing a negative electrode sheet for a lithium ion secondary battery according to any one of claims 10 to 15.

17. The insulating material contains at least one selected from alumina, silica, acrylic resin, magnesia, calcia, titania, zirconia, boehmite, and magnesium hydroxide. A method for manufacturing a negative electrode sheet for a lithium ion secondary battery according to any one of claims 10 to 16.

18. On one surface of the current collector, A negative electrode for a lithium ion secondary battery in which a negative electrode active material layer containing at least a negative electrode active material and a binder is formed, On a first surface, which is the surface of the negative electrode active material layer opposite to the current collector, there is further a high-resistance layer containing at least a solid electrolyte and a binder, The binder contained in the high-resistance layer contains at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts, The binder contained in the negative electrode active material layer is at least one selected from polyacrylic acid and its salts. A negative electrode for an all-solid-state lithium ion secondary battery.

19. At the interface between the negative electrode active material layer and the high-resistance layer, a mixed layer of the negative electrode active material layer and the high-resistance layer having a thickness smaller than the thickness of the negative electrode active material layer is formed. A negative electrode for an all-solid-state lithium ion secondary battery according to claim 18.

20. The D50 particle size at which the cumulative volume in the particle size distribution of the solid electrolyte particles is 50% is 0.2 μm or more and 0.8 μm or less. The negative electrode for an all-solid-state lithium-ion secondary battery according to claim 18 or 19.

21. Among the total weight of the solid materials constituting the high-resistance layer, the weight of styrene-butadiene rubber contained in the high-resistance layer is 3% by weight or more and 6% by weight or less. The negative electrode for an all-solid-state lithium-ion secondary battery according to any one of claims 18 to 20.

22. Among the total weight of the solid materials constituting the negative electrode active material layer, the total weight of polyacrylic acid and its salts among the binder materials contained in the negative electrode active material layer is 3% by weight or more and 6% by weight or less. The negative electrode for an all-solid-state lithium-ion secondary battery according to any one of claims 18 to 21.

23. An all-solid-state lithium-ion secondary battery including a positive electrode electrode having a positive electrode active material layer formed on a current collector, a negative electrode, and a solid electrolyte, wherein the negative electrode is the negative electrode according to any one of claims 18 to 22. An all-solid-state lithium-ion secondary battery.

24. On a sheet-shaped current collector, (A) A step of applying a negative electrode active material slurry containing at least a negative electrode active material and a binder; (B) A step of applying a high-resistance layer slurry containing at least a solid electrolyte and a binder on the surface of the negative electrode active material slurry; (C) A step of simultaneously drying the slurries applied in the step (A) and the step (B); A method for manufacturing a negative electrode for an all-solid-state lithium-ion secondary battery, including at least these steps in this order, The binder contained in the high-resistance layer slurry contains at least styrene-butadiene rubber and at least one selected from carboxymethyl cellulose and its salts. The binder contained in the negative electrode active material slurry is at least one selected from polyacrylic acid and its salts. A method for manufacturing a negative electrode for an all-solid-state lithium-ion secondary battery. Claim 25 A method for manufacturing a negative electrode sheet for an all-solid-state lithium-ion secondary battery for manufacturing a negative electrode for an all-solid-state lithium-ion secondary battery by the manufacturing method according to claim 24, comprising: A method for manufacturing a negative electrode sheet for an all-solid-state lithium-ion secondary battery, wherein a negative electrode active material slurry containing at least a negative electrode active material and a binder, and a high-resistance layer slurry containing at least a solid electrolyte and a binder are continuously applied in a direction in which a current collector sheet is continuously conveyed.

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