Battery manufacturing method and battery

Abstract

The present invention provides a method for manufacturing a battery and a battery in which the adhesion between the resin current collector and the electrode active material layer is excellent. [Solution] A method for manufacturing a battery, comprising the steps of: applying a slurry (1) containing a first resin and a second resin to one or both sides of a substrate and solidifying it to form a resin layer to obtain a resin current collector; and applying a slurry (2) containing an electrode active material and a solvent onto the resin layer of the resin current collector and solidifying it to form an electrode active material layer to obtain an electrode, wherein the first resin is a resin that does not dissolve in the solvent of the slurry (2), and the second resin is a resin that dissolves in the solvent of the slurry (2).

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a battery and a battery.

Background Art

[0002] For the purpose of weight reduction of batteries, resin current collectors have been developed. For example, Patent Document 1 discloses a resin current collector having a conductive resin layer in which a conductive filler is dispersed in a resin and a fluororesin layer laminated on the conductive resin layer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to further improve the safety of the battery, it is necessary to improve the adhesion between the resin current collector and the electrode active material layer.

[0005] The present disclosure has been made under the above circumstances. An object of the present disclosure is to provide a method for manufacturing a battery and a battery having excellent adhesion between a resin current collector and an electrode active material layer.

Means for Solving the Problems

[0006] Specific means for solving the above problems include the following aspects. <1> A step of applying a slurry (1) containing a first resin and a second resin to one or both sides of a substrate and solidifying it to form a resin layer, thereby obtaining a resin current collector; A step of applying a slurry (2) containing an electrode active material and a solvent onto the resin layer of the resin current collector and solidifying it to form an electrode active material layer, thereby obtaining an electrode, The first resin is a resin that does not dissolve in the solvent of the slurry (2), The second resin is a resin that dissolves in the solvent of the slurry (2). Battery manufacturing method. <2> The mass ratio of the first resin to the total of the first resin and the second resin contained in the slurry (1) is 10% by mass to 85% by mass. <1> The battery manufacturing method described above. <3> The device comprises a resin current collector having a substrate and a resin layer disposed on one or both sides of the substrate, and an electrode having an electrode active material layer in contact with the resin layer of the resin current collector, The resin layer of the resin current collector contains a first resin and a second resin, The first resin is a resin that does not show solubility in the solvent species of the residual solvent in the electrode active material layer. The second resin is a resin that is soluble in the solvent species of the residual solvent in the electrode active material layer. battery. <4> The device comprises a resin current collector having a substrate and a resin layer disposed on one or both sides of the substrate, and an electrode having an electrode active material layer in contact with the resin layer of the resin current collector, The resin layer of the resin current collector contains a conductive material, The electrode active material layer contains a binder resin, The boundary between the resin layer and the electrode active material layer has a region where the conductive material of the resin layer and the binder resin of the electrode active material layer are mixed. battery. <5> It is a solid-state battery. <3> or <4> The battery listed. [Effects of the Invention]

[0007] According to this disclosure, a method for manufacturing a battery and a battery are provided that exhibit excellent adhesion between a resin current collector and an electrode active material layer. [Brief explanation of the drawing]

[0008] [Figure 1]It is a partial cross-sectional view showing an example of the layer structure of a solid-state battery. [Figure 2] It is an example of a component profile of a negative pole cross-section based on Raman spectroscopic analysis. [Figure 3] It is another example of a component profile of a negative pole cross-section based on Raman spectroscopic analysis.

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be described. These descriptions and examples are illustrative of the embodiments and do not limit the scope of the embodiments.

[0010] In the present disclosure, when an embodiment is described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. The sizes of the members in each figure are conceptual, and the relative relationships of the sizes between the members are not limited thereto.

[0011] In the present disclosure, the term "step" includes not only an independent step but also this term if the purpose of the step is achieved even when it cannot be clearly distinguished from other steps.

[0012] In the present disclosure, "A and / or B" is synonymous with "at least one of A and B". That is, "A and / or B" means that it may be only A, only B, or a combination of A and B.

[0013] In the present disclosure, the numerical range indicated by using "~" indicates a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described step by step in the present disclosure, the upper limit value or the lower limit value described in one numerical range may be replaced with the upper limit value or the lower limit value of the numerical range described in other step-by-step descriptions. Also, in the numerical ranges described in the present disclosure, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples.

[0014] When referring to the amount of each component in a composition in this disclosure, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, it refers to the total amount of those multiple substances present in the composition.

[0015] <Battery manufacturing method> The battery manufacturing method disclosed herein is A step of obtaining a resin current collector by applying a slurry (1) containing a first resin and a second resin to one or both sides of a substrate and solidifying it to form a resin layer, The process includes the steps of applying a slurry (2) containing an electrode active material and a solvent onto the resin layer of a resin current collector and solidifying it to form an electrode active material layer, thereby obtaining an electrode, The first resin is a resin that does not dissolve in the solvent of slurry (2), The second resin is a resin that dissolves in the solvent of slurry (2).

[0016] The battery manufacturing method of this disclosure involves manufacturing one or both of the negative electrode and the positive electrode by the above-described process. The battery manufactured by the battery manufacturing method of this disclosure exhibits excellent adhesion between the resin current collector and the electrode active material layer. The mechanism is presumed to be as follows.

[0017] The resin layer of the resin current collector is a resin layer formed using a slurry (1) containing a first resin and a second resin. Therefore, the resin layer of the resin current collector contains both a first resin and a second resin. When slurry (2) is applied to the resin layer of the resin current collector, the first resin, being insoluble in the solvent of slurry (2), helps maintain the shape of the resin layer. On the other hand, the second resin, being soluble in the solvent of slurry (2), improves the wettability of slurry (2) to the resin layer. As a result, it is presumed that the electrode active material layer formed by the solidification of slurry (2) adheres closely to the resin layer.

[0018] Batteries manufactured by the battery manufacturing method of this disclosure have excellent adhesion between the resin current collector and the electrode active material layer, making them less prone to cracking of the electrodes and allowing the internal resistance of the battery to be kept low.

[0019] In this disclosure, resins that dissolve in a solvent are referred to as "soluble resins," and resins that do not dissolve in a solvent are referred to as "insoluble resins." The determination of whether a resin is a "soluble resin" or an "insoluble resin" is made by the following method. Add 0.025 g of resin to 10 mL of solvent at a temperature of 27.5°C ± 2.5°C and gently stir for 30 minutes using a magnetic stirring bar and magnetic stirrer. After stirring, visual inspection determines whether the resin is dissolved (i.e., not separated (including precipitation and suspension), colloid, emulsion, or suspension) or whether it is an "insoluble resin". If resin remains (i.e., separated (including precipitation and suspension), colloid, emulsion, or suspension), it is an "insoluble resin".

[0020] The components of the battery manufacturing method of this disclosure will be described in order below.

[0021] [Slurry (1) and resin layer] Slurry (1) is prepared by dissolving or dispersing a first resin and a second resin in a solvent. The first resin may be one type or two or more types. The second resin may be one type or two or more types.

[0022] Examples of first and second resins include fluororesins (polyvinylidene fluoride, polytetrafluoroethylene, etc.), vinyl resins (polyvinyl chloride, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl acetal, polyvinylpyrrolidone, acrylic resin, etc.), polyolefin resins (polyethylene, polypropylene, polymethylpentene, polycycloolefin, etc.), polyester resins (polyethylene terephthalate, etc.), and various composite resins of these resins. Furthermore, engineering plastics such as synthetic rubber (styrene-butadiene rubber, polyacrylonitrile, etc.), epoxy resins, silicone resins, and polyethernitrile can also be used as first and second resins, respectively.

[0023] The molecular weights of the first resin and the second resin are preferably 1,000 to 300,000, more preferably 5,000 to 200,000, and even more preferably 10,000 to 150,000, respectively. The molecular weight of the first resin is preferably greater than the molecular weight of the second resin.

[0024] In this disclosure, the molecular weight of the resin is the value obtained by converting the molecular weight measured by gel permeation chromatography (GPC) to the molecular weight of standard polystyrene. Specifically, using the GPC instrument "HLC8120GPC" (Tosoh Corporation) and four columns "TSKgel G-4000HXL," "TSKgel G-3000HXL," "TSKgel G-2500HXL," and "TSKgel G-2000HXL" (all from Tosoh Corporation), the molecular weight distribution is measured using tetrahydrofuran as the mobile phase, a measurement temperature of 40°C, a flow rate of 1 mL / min, and a radioisotope detector (RI), and the weight-average molecular weight is calculated.

[0025] Vinyl resins are preferred as the first and second resins, and functional group-containing vinyl resins are particularly preferred. The "vinyl resin" in this disclosure is a resin obtained by polymerizing or copolymerizing a monomer containing a polymerizable unsaturated group of formula (1) below, and various modifications may be performed after (co)polymerization.

[0026] C(-R)2=C(-R)2...Equation (1) In formula (1), R is preferably a hydrogen atom or an organic group, and the multiple Rs contained in the molecule may be the same or different from each other.

[0027] The molecular weight of the vinyl resin is preferably 1,000 to 300,000, more preferably 5,000 to 200,000, and even more preferably 10,000 to 150,000 as a calculated molecular weight. The calculated molecular weight of the vinyl resin is obtained by calculating the average molecular weight of one unit from the molecular weights and number of each organic group and substituent (e.g., acetal group, acetyl group, hydroxyl group, alkyl group, etc.) and multiplying this by the average degree of polymerization.

[0028] Vinyl resins (especially functional group-containing vinyl resins) preferably have at least one polar functional group selected from the group consisting of amide groups, imide groups, hydroxyl groups, carboxylic acid groups, sulfonic acid groups, phosphoric acid groups, silanol groups, amino groups, pyrrolidone groups, and nitrile groups, and more preferably have a hydroxyl group, from the viewpoint of improving the dispersibility of conductive materials in the slurry (1). The concentration of the functional group in the vinyl resin may be 0.1 mmol / g to 23 mmol / g, preferably 0.5 mmol / g to 10 mmol / g, and more preferably 1.0 mmol / g to 5.0 mmol / g.

[0029] From the viewpoint of mutual compatibility, it is preferable that the first resin and the second resin are of the same type. Methods for differentiating between soluble and insoluble resins include, for example, adjusting the molecular weight, introducing polar or nonpolar groups, and introducing side chains.

[0030] The mass ratio of the first resin to the total amount of the first resin and the second resin contained in the slurry (1) is preferably 10% by mass to 85% by mass. When the first resin is 10% by mass or more, the shape of the resin layer is easily maintained when slurry (2) is applied to the resin layer of the resin current collector. When the first resin is 85% by mass or less, the slurry (2) adheres well to the resin layer when it is applied to the resin layer of the resin current collector. The mass ratio of the first resin to the total of the first and second resins contained in the slurry (1) is more preferably 15% to 70% by mass, and even more preferably 20% to 40% by mass.

[0031] Preferably, the volume percentage of the first resin in the slurry (1) relative to the total of the first and second resins is 10% to 85% by volume. When the first resin is present in an amount of 10% by volume or more, the shape of the resin layer is more easily maintained when slurry (2) is applied to the resin layer of the resin current collector. When the first resin is 85% by volume or less, the slurry (2) adheres well to the resin layer when it is applied to the resin layer of the resin current collector. The volume ratio of the first resin to the total of the first and second resins contained in the slurry (1) is more preferably 15% to 70% by volume, and even more preferably 20% to 40% by volume. Here, volume refers to the volume in the resin layer when the slurry (1) solidifies and forms a resin layer.

[0032] The solvent for slurry (1) should be selected according to the resin types of the first and second resins. Examples of solvents for slurry (1) include alcohols.

[0033] The slurry (1) may contain other components besides the first resin and the second resin. Examples of other components include conductive materials and fillers.

[0034] Examples of conductive materials include carbon materials, conductive polymers, and metal particles. Examples of carbon materials include particulate carbon materials and fibrous carbon materials. Examples of particulate carbon materials include graphite, acetylene black, and Ketjenblack. Examples of fibrous carbon materials include carbon nanotubes, carbon nanofibers, and vapor-grown carbon fibers (VGCF). Examples of conductive polymers include polythiophene, polyacetylene, poly(p-phenylene), and polyisothianaphthene. Examples of metal particles include nickel, copper, iron, and stainless steel.

[0035] As a conductive material, carbon material is preferred from the viewpoint of adhesion between the resin layer and the electrode active material layer, and from the viewpoint of the electronic conductivity of the resin layer.

[0036] The content of the conductive material is preferably 5% to 50% by mass, more preferably 10% to 40% by mass, and even more preferably 15% to 30% by mass, relative to the total solid content of the resin layer.

[0037] A metal layer is preferred as the substrate to which the slurry (1) is applied (i.e., the substrate for the resin current collector). Examples of metal layers include metal foils made of stainless steel, aluminum, nickel, iron, copper, titanium, etc.

[0038] The thickness of the substrate may be, for example, 1 μm to 50 μm, 3 μm to 25 μm, or 5 μm to 10 μm.

[0039] The slurry (1) is applied to one or both sides of the substrate. The slurry (1) solidifies on the substrate to form a resin layer, and a resin current collector is obtained.

[0040] Solidification of the slurry (1) on the substrate is performed, for example, by applying heat capable of removing the solvent from the slurry (1). If the first resin is a thermosetting resin, it is preferable to further apply heat to cure the first resin after applying heat to remove the solvent.

[0041] From the viewpoint of the battery's energy density, the thinner the resin layer, the better, but from the viewpoint of adhesion with the electrode active material layer, it is preferable that it is not too thin. The resin layer thickness is preferably 0.1 μm to 5 μm, more preferably 0.5 μm to 4 μm, and even more preferably 1 μm to 3 μm or less.

[0042] [Slurry (2) and electrode active material layer] Slurry (2) is prepared by dissolving or dispersing electrode active material (negative electrode active material or positive electrode active material) in a solvent.

[0043] Examples of solvents for slurry (2) include butyl butyrate, diisobutyl ketone, and tetralin.

[0044] Examples of negative electrode active materials include Li-based active materials such as metallic lithium, carbon-based active materials such as graphite, oxide-based active materials such as lithium titanate, and Si-based active materials such as elemental Si. The negative electrode active material may be used alone or in a mixture of two or more types.

[0045] Examples of positive electrode active materials include lithium transition metal composite oxides. Examples of lithium transition metal composite oxides include LiMn2O4, LiMO2 (where M is Ni, Co, or Mn), and LiMPO4 (where M is Fe, Co, Ni, or Mn). The positive electrode active material may be used alone or as a mixture of two or more types.

[0046] The slurry (2) may further contain at least one of a binder resin, a solid electrolyte, and a conductive material.

[0047] Examples of binder resins include rubbers such as butadiene rubber (BR), acrylate butadiene rubber (ABR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), and butyl rubber (isobutylene-isoprene rubber); halogenated vinyl resins; and polyolefins.

[0048] The solid electrolyte preferably includes one selected from the group consisting of sulfide solid electrolytes, oxide solid electrolytes, and halide solid electrolytes. The sulfide solid electrolyte preferably contains sulfur (S) as the main component of the anionic element, and further contains, for example, Li and A. Element A is at least one selected from the group consisting of P, As, Sb, Si, Ge, Sn, B, Al, Ga, and In. The oxide solid electrolyte contains oxygen (O) as the main component of the anionic element, and may also contain, for example, Li and Q elements. The Q element is at least one selected from the group consisting of Nb, B, Al, Si, P, Ti, Zr, Mo, W, and S. A suitable halide solid electrolyte is one containing Li, M, and X (where M represents at least one of Ti, Al, and Y, and X represents F, Cl, or Br).

[0049] Examples of conductive materials include carbon materials, conductive polymers, and metal particles. Examples of carbon materials include particulate carbon materials and fibrous carbon materials. Examples of particulate carbon materials include graphite, acetylene black, and Ketjenblack. Examples of fibrous carbon materials include carbon nanotubes, carbon nanofibers, and vapor-grown carbon fibers (VGCF). Examples of conductive polymers include polythiophene, polyacetylene, poly(p-phenylene), and polyisothianaphthene. Examples of metal particles include nickel, copper, iron, and stainless steel.

[0050] The slurry (2) is applied to the resin layer of the resin current collector. The slurry (2) solidifies on the resin layer to form an electrode active material layer, and an electrode is obtained.

[0051] The solidification of the slurry (2) on the resin layer of the resin current collector is performed, for example, by applying heat that can remove the solvent from the slurry (2). If the binder resin is a thermosetting resin, it is preferable to further apply heat to cure the binder resin after applying heat to remove the solvent.

[0052] The thickness of the electrode active material layer is preferably adjusted within the range of 1 μm to 100 μm from the viewpoint of the battery's energy density, charge / discharge characteristics, and suppression of delamination.

[0053] The electrodes prepared using slurry (1) and slurry (2) may be either a negative electrode or a positive electrode, or both.

[0054] The battery manufacturing method disclosed herein includes a step of obtaining electrodes, followed by a further step, A process for manufacturing battery elements suitable for the intended battery shape and application, Preferably, the process includes the steps of housing the battery elements in an outer casing, arranging the positive electrode tab and the negative electrode tab, and vacuum sealing.

[0055] Examples of battery elements include a laminate in which electrodes and solid electrolytes are alternately stacked, and a laminate in which electrodes and separators are alternately stacked and impregnated with an electrolyte. Examples of outer packaging include aluminum laminate film packs and metal cans.

[0056] <Battery> The batteries manufactured by the battery manufacturing method of this disclosure exhibit two characteristics, which are described below as the first battery and the second battery.

[0057] The first battery of this disclosure is The device comprises a current collector having a substrate and a resin layer disposed on one or both sides of the substrate, and an electrode having an electrode active material layer in contact with the resin layer of the current collector, The resin layer of the resin current collector contains a first resin and a second resin, The first resin is a resin that does not show solubility in the solvent species of the residual solvent in the electrode active material layer. The second resin is a resin that is soluble in the solvent species of the residual solvent in the electrode active material layer. One or both of the negative and positive electrodes of the first battery are the electrodes described above.

[0058] The residual solvent in the electrode active material layer originates from the slurry used to form the electrode active material layer, i.e., the slurry (2) in the battery manufacturing method of this disclosure.

[0059] Whether the resin contained in the resin layer of the resin current collector is soluble in the solvent species of the residual solvent in the electrode active material layer is confirmed by the following method. Analyze the resin layer of the resin current collector to identify at least two types of resin. Analyze the electrode active material layer to identify the type of solvent remaining. Using the identified resin type and solvent type, determine whether it is a "soluble resin" or an "insoluble resin" using the method described above.

[0060] The second battery in this disclosure is The device comprises a current collector having a substrate and a resin layer disposed on one or both sides of the substrate, and an electrode having an electrode active material layer in contact with the resin layer of the current collector, The resin layer of the resin current collector contains a conductive material. The electrode active material layer contains a binder resin, The current collector has a region at the boundary between the resin layer and the electrode active material layer where the conductive material of the resin layer and the binder resin of the electrode active material layer are mixed. One or both of the negative and positive electrodes of the second battery are the electrodes described above.

[0061] The second battery of this disclosure has electrodes formed using a slurry (1) which also contains a conductive material and a slurry (2) which also contains a binder resin. When slurry (2) is applied to the resin layer of the resin current collector, at least a portion of the second resin in the resin layer dissolves in the solvent of slurry (2). At that time, the binder resin in slurry (2) penetrates into the resin layer, and a region is formed at the boundary between the resin layer and the electrode active material layer where the conductive material of the resin layer and the binder resin of the electrode active material layer are mixed.

[0062] The region where the conductive material of the resin layer and the binder resin of the electrode active material layer are mixed occupies, for example, 1 / 5 to 4 / 5 of the thickness of the resin layer.

[0063] Regions where the conductive material of the resin layer and the binder resin of the electrode active material layer are mixed can be identified by performing Raman spectroscopy on the electrode cross-section and creating a component profile in the thickness direction. An example of Raman spectroscopy is shown in Example 6, described later.

[0064] The batteries described herein include solid-state batteries and liquid-state batteries. The battery manufacturing method and the battery disclosed herein are suitable for solid-state batteries.

[0065] The solid-state batteries of this disclosure include so-called all-solid-state batteries that use a solid electrolyte as the electrolyte. In the solid-state batteries of this disclosure, the solid electrolyte may contain less than 10% by mass of electrolyte relative to the total amount of electrolyte, or it may be a composite solid electrolyte containing an inorganic solid electrolyte and a polymer electrolyte.

[0066] The shape and applications of the solid-state batteries of this disclosure are not limited. The solid-state batteries of this disclosure can be applied, for example, to HEVs (Hybrid Electric Vehicles), PHEVs (Plug-in Hybrid Electric Vehicles), and BEVs (Battery Electric Vehicles).

[0067] Figure 1 is a partial cross-sectional view showing an example of the layer configuration of the solid-state battery of this disclosure. The solid-state battery 10 comprises a solid electrolyte layer 20, a negative electrode 30, and a positive electrode 40. The negative electrode 30 comprises a negative electrode active material layer 32 and a negative electrode current collector 34. The negative electrode current collector 34 has a metal layer 3A (an example of a substrate) and a resin layer 3B. The positive electrode 40 comprises a positive electrode active material layer 42 and a positive electrode current collector 44. The positive electrode current collector 44 has a metal layer 4A (an example of a substrate) and a resin layer 4B. [Examples]

[0068] The manufacturing method and the battery of this disclosure will be described in more detail below with reference to examples. The materials, processing procedures, processing conditions, etc., shown in the following examples can be modified as appropriate without departing from the spirit of this disclosure. Therefore, the manufacturing method and the battery of this disclosure should not be interpreted restrictively by the specific examples shown below.

[0069] In the following descriptions, synthesis, processing, and manufacturing were carried out at room temperature (25°C ± 3°C) unless otherwise specified.

[0070] In the following explanation, "resin current collector" will be referred to as "resin current collector foil."

[0071] The vinyl resins α and β used in Examples 1-6 and Comparative Examples 1-2 are the same. The composition of both resins is as follows. • Vinyl resin α: Polyvinyl butyral: Calculated molecular weight 108,000, hydroxyl groups approximately 31 mol%, butyral groups approximately 68 mol%, acetyl groups approximately 1 mol%, functional group concentration 2.8 mmol / g • Vinyl resin β: Polyvinyl butyral: Calculated molecular weight 32,000, hydroxyl groups approximately 19 mol%, butyral groups approximately 79 mol%, acetyl groups approximately 2 mol%, functional group concentration 1.5 mmol / g

[0072] <Example 1> [Manufacturing of resin current collector foil] • First resin: Vinyl resin α that is insoluble in the solvent of slurry (2): 56 parts by mass • Second resin: Vinyl resin β soluble in the solvent of slurry (2): 24 parts by mass ·Conductive material: Carbon material: 20 parts by mass The above materials were added to 2-ethylhexanol and stirred to obtain slurry (1). Slurry (1) was coated onto one side of a Ni foil using the blade method. The coated material was placed on a hot plate at 80°C for 30 minutes, and then on a hot plate at 170°C for 30 minutes to obtain a resin current collector foil.

[0073] [Fabrication of the negative electrode] • Negative electrode active material (silicon; Si): 49.3 parts by mass ·Sulfide solid electrolyte (SE; Li2S-P2S5): 41.5 parts by mass • Vapor-grown carbon fiber (VGCF): 6.4 parts by mass ·SBR: 2.8 parts by mass The above materials were added to butyl butyrate and stirred and mixed in an ultrasonic disperser to obtain slurry (2). Slurry (2) was coated onto a resin current collector foil using the blade method. The coated material was placed on a 50°C hot plate for 30 minutes, and then on a 170°C hot plate for 30 minutes to form a negative electrode active material layer and obtain a negative electrode.

[0074] <Example 2> A negative electrode was obtained in the same manner as in Example 1, except that the amounts of the first resin and the second resin constituting the slurry (1) were changed as follows. • First resin: Vinyl resin α that is insoluble in the solvent of slurry (2): 48 parts by mass • Second resin: Vinyl resin β soluble in the solvent of slurry (2): 32 parts by mass

[0075] <Example 3> A negative electrode was obtained in the same manner as in Example 1, except that the amounts of the first resin and the second resin constituting the slurry (1) were changed as follows. • First resin: Insoluble vinyl resin α in the solvent of slurry (2): 40 parts by mass • Second resin: Vinyl resin β soluble in the solvent of slurry (2): 40 parts by mass

[0076] <Example 4> A negative electrode was obtained in the same manner as in Example 1, except that the amounts of the first resin and the second resin constituting the slurry (1) were changed as follows. • First resin: Vinyl resin α that is insoluble in the solvent of slurry (2): 32 parts by mass • Second resin: Vinyl resin β soluble in the solvent of slurry (2): 48 parts by mass

[0077] <Example 5> A negative electrode was obtained in the same manner as in Example 1, except that the amounts of the first resin and the second resin constituting the slurry (1) were changed as follows. • First resin: Insoluble vinyl resin α in the solvent of slurry (2): 24 parts by mass • Second resin: Vinyl resin β soluble in the solvent of slurry (2): 56 parts by mass

[0078] <Example 6> A negative electrode was obtained in the same manner as in Example 1, except that the amounts of the first resin and the second resin constituting the slurry (1) were changed as follows. • First resin: Insoluble vinyl resin α in the solvent of slurry (2): 16 parts by mass • Second resin: Vinyl resin β soluble in the solvent of slurry (2): 64 parts by mass

[0079] <Comparative Example 1> A negative electrode was obtained in the same manner as in Example 1, except that the amounts of the first resin and the second resin constituting the slurry (1) were changed as follows. • First resin: Insoluble vinyl resin α in the solvent of slurry (2): 0 parts by mass • Second resin: Vinyl resin β soluble in the solvent of slurry (2): 80 parts by mass

[0080] <Comparative Example 2> A negative electrode was obtained in the same manner as in Example 1, except that the amounts of the first resin and the second resin constituting the slurry (1) were changed as follows. • First resin: Vinyl resin α that is insoluble in the solvent of slurry (2): 80 parts by mass • Second resin: Vinyl resin β soluble in the solvent of slurry (2): 0 parts by mass

[0081] <Performance Evaluation> [Confirmation of the presence or absence of delamination] We tilted and inverted the negative electrode to check whether delamination occurred due to gravity. The results are shown in Table 1. G: No delamination occurs. NG: Delamination occurred between the resin current collector foil and the negative electrode active material layer.

[0082] [Measurement of peel strength] The negative electrode (resin current collector foil and negative electrode active material layer) was punched out in a circular shape with a diameter of 14.5 mm, and a peel test was performed according to the following procedure. The negative electrode's Ni foil side was fixed to the sample stage of a tensile testing machine (STB-1225S, A&D Company, Limited) using double-sided tape. On the negative electrode's negative electrode active material layer side, there is a diameter of 2.28 mm (area 1 cm²). 2 A circular piece of double-sided tape was attached with a pressing load of 50N. The other side of the double-sided tape was attached to the jig of the tensile testing machine. The jig of the tensile testing machine was lifted, and the load (kPa) at the point when the negative electrode active material layer peeled off from the resin current collector foil was measured, and the tape area (1cm²) was measured. 2 The peel strength was defined as the value obtained by dividing by ( ). The measurement results are shown in Table 1.

[0083] In Comparative Example 2, the negative electrode was so susceptible to delamination due to gravity that it was impossible to measure the delamination strength.

[0084] [Table 1]

[0085] Table 1 shows the presence or absence of delamination and the values ​​of delamination strength, indicating that the slurry for forming the resin layer of the resin current collector foil contains both the first resin and the second resin, resulting in excellent adhesion between the resin layer and the electrode active material layer.

[0086] <Raman spectroscopy> Cross-sections were prepared from the negative electrodes of Example 6 and Comparative Example 2, and each cross-section was subjected to Raman spectroscopy. A Raman spectrometer XploRA PLUS (Horiba, Ltd.) was used, with a measurement wavenumber range of 200 cm². -1 ~4000cm -1 The analysis was performed using a laser wavelength of 532 nm.

[0087] Wave number 500cm -1 The nearby peak represents Si (negative electrode active material), wavenumber 1000 cm. -1 The nearby peak is SBR (anode binding resin), wavenumber 2700 cm. -1 The nearby peak was designated as carbon (C).

[0088] Figures 2 and 3 show the component profiles in the thickness direction of the negative electrode cross-section based on Raman spectroscopy. Figure 2 is the component profile of Example 6, and Figure 3 is the component profile of Comparative Example 2. The horizontal axis represents the relative distance (μm) in the thickness direction of the negative electrode cross-section. The left direction on the horizontal axis is the negative electrode active material layer, and the right direction is the Ni foil. In the thickness-direction component profile of Example 6, the peak top of C was located closer to the negative electrode active material layer than the peak top of SBR, and the peaks of C and SBR almost overlapped. In the thickness-direction component profile of Comparative Example 2, the peak top of SBR was located closer to the negative electrode active material layer than the peak top of C, and the peaks of C and SBR hardly overlapped. These findings meant that in Example 6, there was a region at the boundary between the resin layer and the negative electrode active material layer of the resin current collector foil where the conductive material of the resin layer and the binder resin of the negative electrode active material layer were mixed. [Explanation of Symbols]

[0089] 10 solid state battery 20 Solid electrolyte layer 30 negative electrode, 32 negative electrode active material layer, 34 negative electrode current collector, 3A metal layer, 3B resin layer 40 positive electrode, 42 positive electrode active material layer, 44 positive electrode current collector, 4A metal layer, 4B resin layer

Claims

1. A step of obtaining a resin current collector by applying a slurry (1) containing a first resin and a second resin to one or both sides of a substrate and solidifying it to form a resin layer, The process includes the steps of applying a slurry (2) containing an electrode active material and a solvent onto the resin layer of the resin current collector and solidifying it to form an electrode active material layer, thereby obtaining an electrode, The first resin is a resin that does not dissolve in the solvent of the slurry (2), The second resin is a resin that dissolves in the solvent of the slurry (2). Battery manufacturing method.

2. The mass ratio of the first resin to the total of the first resin and the second resin contained in the slurry (1) is 10% by mass to 85% by mass. A method for manufacturing a battery according to claim 1.

3. The device comprises a resin current collector having a substrate and a resin layer disposed on one or both sides of the substrate, and an electrode having an electrode active material layer in contact with the resin layer of the resin current collector, The resin layer of the resin current collector contains a first resin and a second resin, The first resin is a resin that does not show solubility in the solvent species of the residual solvent in the electrode active material layer. The second resin is a resin that is soluble in the solvent species of the residual solvent in the electrode active material layer. battery.

4. The device comprises a resin current collector having a substrate and a resin layer disposed on one or both sides of the substrate, and an electrode having an electrode active material layer in contact with the resin layer of the resin current collector, The resin layer of the resin current collector contains a conductive material, The electrode active material layer contains a binder resin, The boundary between the resin layer and the electrode active material layer has a region where the conductive material of the resin layer and the binder resin of the electrode active material layer are mixed. battery.

5. The battery according to claim 3 or claim 4, which is a solid-state battery.

Images