Method for manufacturing electrode film, electrode film, and battery

Abstract

Provided is a method for producing an electrode film, comprising: adhering polyvinylidene fluoride to active material particles; mixing the active material particles to which polyvinylidene fluoride adheres with polytetrafluoroethylene to obtain a mixture; and fibrating the polytetrafluoroethylene in the mixture, the fibrating being carried out at a temperature of 50 DEG C or higher, the mixture containing no solvent.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing an electrode film, an electrode film, and a battery. Background Art

[0002] In a battery such as a lithium ion secondary battery, an electrode in a state where active material particles are fixed to the surface of a current collector such as a metal foil using an adhesive is used. As a method for manufacturing an electrode, a method of coating a composition prepared by mixing active material particles and an adhesive with a solvent on the surface of a current collector (also referred to as a wet method) and a method of fixing active material particles to a current collector using an adhesive without using a solvent (also referred to as a dry method) are known.

[0003] As a method for manufacturing an electrode based on the dry method, a method of using a resin having a property of fibrillating (fine fibrillating) when a shear force is applied as an adhesive has been proposed. For example, Japanese Patent Application Laid-Open No. 2022-3694 describes the following method: an electrode film is produced by fibrillating PTFE in a mixture containing active material particles and polytetrafluoroethylene (PTFE), and then the electrode film is integrated with a current collector to manufacture an electrode. Summary of the Invention

[0004] Although Japanese Patent Application Laid-Open No. 2022-3694 describes that calendering for producing an electrode film containing fibrillated PTFE can be performed at a temperature of 10°C to 300°C, the relationship between the physical properties of the electrode film and the temperature conditions of the calendering treatment has not been explored. One embodiment of the present disclosure provides a method for manufacturing an electrode film having excellent tensile strength, an electrode film having excellent tensile strength, and a battery including the electrode film having excellent tensile strength.

[0005] In the present disclosure, the following embodiments are included. A first aspect of the present disclosure is a method for manufacturing an electrode film, including: causing polyvinylidene fluoride to adhere to active material particles; mixing the active material particles to which polyvinylidene fluoride has adhered with polytetrafluoroethylene to obtain a mixture; and fibrillating the polytetrafluoroethylene in the mixture, wherein the fibrillating is performed at a temperature of 50°C or higher, and the mixture does not contain a solvent.

[0006] In the method for manufacturing an electrode film according to the first aspect of the present disclosure, the fibrillating may be performed at a temperature of 100°C or higher.

[0007] In the method for manufacturing an electrode film according to the first aspect of the present disclosure, the fibrillating may be performed at a temperature of 200°C or lower.

[0008] In the method for manufacturing an electrode film according to the first aspect of the present disclosure, the fibrillation may be carried out at a temperature of 180°C or lower.

[0009] In the method for manufacturing an electrode film according to the first aspect of the present disclosure, the fibrillation may include forming a mixture into a film shape.

[0010] In the method for manufacturing an electrode film according to the first aspect of the present disclosure, the amount of polyvinylidene fluoride relative to the active material particles may be 1% by mass or more and 10% by mass or less with respect to 100 parts by mass of the active material particles.

[0011] In the method for manufacturing an electrode film according to the first aspect of the present disclosure, the amount of polytetrafluoroethylene relative to the active material particles may be 1% by mass or more and 10% by mass or less with respect to 100 parts by mass of the active material particles.

[0012] A second aspect of the present disclosure is an electrode film including: active material particles; polyvinylidene fluoride attached to the active material particles; and fibrous polytetrafluoroethylene.

[0013] In the electrode film according to the second aspect of the present disclosure, the number of fibrous polytetrafluoroethylene intersecting a straight line having a length of 20 μm at an arbitrary position in the cross-sectional image of the electrode film may be 5 or more.

[0014] In the electrode film according to the second aspect of the present disclosure, the number of fibrous polytetrafluoroethylene intersecting the straight line may be 20 or more.

[0015] In the electrode film according to the second aspect of the present disclosure, at least a part of the fibrous polytetrafluoroethylene may be attached to the active material particles.

[0016] In the electrode film according to the second aspect of the present disclosure, the coating rate of polyvinylidene fluoride on the surface of the active material particles may be 5% or more.

[0017] A third aspect of the present disclosure is a battery including the electrode film according to the second aspect of the present disclosure.

[0018] According to one embodiment of the present disclosure, there are provided a method for manufacturing an electrode film having excellent tensile strength, an electrode film having excellent tensile strength, and a battery including the electrode film having excellent tensile strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Hereinafter, features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described with reference to the drawings, in which like reference numerals denote like elements. Figure 1 This is a diagram schematically showing an example of the laminated structure of the electrode body included in the battery. Figure 2 This is an SEM image of the cross-section of the electrode film (calendered at 150°C) produced in the example. Detailed Description of the Invention

[0020] In the present disclosure, a numerical range indicated by "~" means a range including the numerical values described before and after "~" as the minimum value and the maximum value, respectively. In the numerical ranges described stepwise in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range can be replaced with the upper limit value or the lower limit value of other stepwise-described numerical ranges. In the numerical ranges described in the present disclosure, the upper limit value or the lower limit value described in a certain numerical range can be replaced with the value shown in the examples. In the present disclosure, the expression "process" not only refers to an independent process, but also includes a process that cannot be clearly distinguished from other processes as long as the desired purpose of the process can be achieved. In the present disclosure, a combination of two or more preferred modes is a more preferred mode. In the present disclosure, regarding the amount of each component, in the case where there are multiple substances corresponding to each component, unless otherwise specified, it means the total amount of the multiple substances.

[0021] <Method for Manufacturing Electrode> The method for manufacturing the electrode film of the present disclosure includes: causing polyvinylidene fluoride (hereinafter also referred to as PVdF) to adhere to the active material particles; mixing the active material particles adhered with PVdF with PTFE to obtain a mixture; and fibering the PTFE in the mixture, the fibering is carried out at a temperature of 50°C or higher, the mixture does not contain a solvent.

[0022] In the present disclosure, "electrode film" includes a substance that functions as an active material of an electrode, and means a film-shaped object in a state capable of standing on its own (i.e., capable of maintaining its shape without a support). The electrode film is used, for example, as an active material layer disposed on one side or both sides of a current collector. The method of the present disclosure does not use a solvent when manufacturing the electrode film. Therefore, the method of the present disclosure is excellent in terms of affinity for organisms and the environment. Moreover, the method of the present disclosure can omit the process of volatilizing the solvent after film formation, and the manufacturing efficiency is excellent.

[0023] The electrode film manufactured by the method of the present disclosure exhibits excellent tensile strength as compared with an electrode film obtained by subjecting PTFE to fibrillation at a temperature of less than 50°C. For example, according to the method of the present disclosure, an electrode film having a tensile strength of 0.5 MPa or more can also be manufactured. If the tensile strength of the electrode film is 0.5 MPa or more, it is advantageous in that damage such as cracks is hardly generated during the manufacturing process of the electrode film. The reason why the electrode film manufactured by the method of the present disclosure exhibits excellent tensile strength can be considered as follows, for example. If PTFE is fibrillated at a temperature of 50°C or more, the fibrillation of PTFE is promoted. Moreover, PVdF attached to the active material particles melts or softens, and the fibrillated PTFE adheres to the active material particles via the melted or softened PVdF. As a result, it is considered that the tensile strength of the obtained electrode film is increased.

[0024] Hereinafter, the step of attaching PVdF to the active material particles is also referred to as "Step 1", the step of mixing the active material particles to which PVdF is attached with PTFE to obtain a mixture is also referred to as "Step 2", and the step of fibrillating PTFE in the mixture is also referred to as "Step 3".

[0025] (Step 1) In Step 1, PVdF is attached to the active material particles. The method of attaching PVdF to the active material particles is not particularly limited and can be carried out by a known method. For example, PVdF can be attached to the active material particles by applying a shear force to a mixture containing the active material particles and PVdF using a device such as a mixer, a stirrer, or a grinder.

[0026] From the viewpoint of effectively attaching the fibrillated PTFE to the active material particles, the amount of PVdF relative to the active material particles is preferably 1% by mass or more, more preferably 2% by mass or more, and still more preferably 3% by mass or more with respect to 100 parts by mass of the active material particles. From the viewpoint of maintaining good electrode performance, the amount of PVdF relative to the active material particles is preferably 10% by mass or less, more preferably 8% by mass or less, and still more preferably 6% by mass or less with respect to 100 parts by mass of the active material particles.

[0027] PVdF can be attached to the entire surface of the active material particles or to a part of the surface of the active material particles. From the viewpoint of effectively attaching the fibrillated PTFE to the active material particles, the coating rate of PVdF on the surface of the active material particles is preferably 5% or more, more preferably 10% or more, and still more preferably 15% or more. From the viewpoint of maintaining good electrode performance, the coating rate of PVdF on the surface of the active material particles is preferably 60% or less, more preferably 50% or less, and still more preferably 40% or less.

[0028] In the present disclosure, the coating rate of PVdF on the surface of the active material particles is measured by an image analysis method. As the image analysis method, for example, a method of performing elemental mapping using EDX (energy dispersive X-ray spectroscopy) can be mentioned. Specifically, the active material particles with PVdF attached to the surface are observed using SEM (scanning electron microscope), and F mapping is performed using EDX. The region X corresponding to the active material particles and the region Y in the region X where the elements (F) contained in PVdF are present are binarized, and the coating rate is calculated according to the following formula. Coating rate (%) = (area of Y / area of X) × 100

[0029] The type of the active material particles used in the manufacture of the electrode film can be either a negative electrode active material for a negative electrode or a positive electrode active material for a positive electrode.

[0030] Specific examples of the negative electrode active material include carbon materials such as graphite, soft carbon, and hard carbon, and silicon.

[0031] Examples of the positive electrode active material include lithium transition metal composite oxides. Examples of the lithium transition metal composite oxides include layered lithium transition metal composite oxides, spinel-type lithium transition metal composite oxides, olivine-type lithium transition metal composite oxides, etc. Specific examples of the layered lithium transition metal composite oxide include compounds represented by LiMO2 (M is at least one transition metal selected from the group consisting of Ni, Co, and Mn), and compounds in which a different element is added to the compound. Examples of the different element include Al, Mg, La, Ti, Zn, B, W, Fe, Cr, V, Ru, Cu, Cd, Ag, Y, Sc, Ga, In, As, Sb, Pt, Au, Si, etc. Specific examples of the spinel-type lithium transition metal composite oxide include LiMn2O4. Specific examples of the olivine-type lithium transition metal composite oxide include LiMPO4 (M is Fe, Co, Ni, or Mn). The positive electrode active material contained in the positive electrode material can be either a single type or two or more types.

[0032] Among the lithium transition metal composite oxides, a layered lithium transition metal composite oxide containing at least one selected from Ni, Co, and Mn as the transition metal is more preferable, a layered lithium transition metal composite oxide containing Ni and at least one selected from Co and Mn as the transition metal is further preferable, and a layered lithium transition metal composite oxide (NCM, nickel cobalt manganese oxide) containing Ni, Co, and Mn as the transition metals respectively is still further preferable.

[0033] The active material particles used in the manufacture of the electrode film may be either a single type or two or more types. There is no particular limitation on the volume average particle diameter of the active material particles, and for example, it may be selected from the range of 5 μm to 30 μm. In the present disclosure, the volume average particle diameter of the particles is the value (D50) at which the cumulative value from the small diameter side becomes 50% in the volume-based particle size distribution measured by the laser diffraction / scattering method.

[0034] In Step 1, the conductive additive may also be attached to the active material particles together with PVdF. When the active material particles are positive electrode active material particles, it is preferable to attach the conductive additive to the active material particles. Specific examples of the conductive additive include carbon materials such as carbon black (acetylene black, thermal black, furnace black, etc.), carbon nanotubes, and graphite.

[0035] The state in which the conductive additive is attached to the active material particles can be obtained, for example, by applying a shear force to a mixture containing the active material particles, the conductive additive, and PVdF using a device such as a mixer, a stirrer, or a grinder.

[0036] (Step 2) In Step 2, the active material particles to which PVdF is attached are mixed with PTFE to obtain a mixture. The method of mixing the active material particles to which PVdF is attached with PTFE is not particularly limited, and known means can be used for implementation.

[0037] From the viewpoint of maintaining the strength of the electrode film, the amount of PTFE relative to the active material particles is preferably 1% by mass or more, more preferably 2% by mass or more, and still further preferably 3% by mass or more with respect to 100 parts by mass of the active material particles. From the viewpoint of maintaining good electrode performance, the amount of PTFE relative to the active material particles is preferably 10% by mass or less, more preferably 8% by mass or less, and still further preferably 6% by mass or less with respect to 100 parts by mass of the active material particles.

[0038] The PTFE mixed with the active material particles in Step 2 may be in the form of particles. The mixture obtained in Step 2 may or may not contain a solvent. From the viewpoint of workability, the mixture obtained in Step 2 preferably does not contain a solvent. In Step 2, at least a part of the PTFE can be fibrillated. In this case, granulated particles can be produced in a state where at least a part of the active material particles are bonded by fibrillated PTFE.

[0039] The mixture obtained in Step 2 may also contain resins other than PVdF and PTFE. As binders other than PVdF and PTFE, specifically, polyethylene, polypropylene, polyethylene terephthalate, cellulose, nitrocellulose, carboxymethyl cellulose, polyethylene oxide, epichlorohydrin, polyacrylonitrile, styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), polyacrylate, polymethacrylate, etc. can be cited.

[0040] When the mixture contains resins other than PVdF and PTFE, the amount thereof can be 20 parts by mass or less, 10 parts by mass or less, or 5 parts by mass or less relative to 100 parts by mass in total of PVdF and PTFE.

[0041] (Step 3) In Step 3, the PTFE in the mixture obtained in Step 2 is fibrillated. The PTFE in the mixture obtained in Step 2 is usually in a state where the PTFE particles form aggregates, and when a shearing force is applied, the aggregates are broken and a part of the particles changes into a fibrous shape. In the present disclosure, in addition to PTFE that is completely in the shape of fibers, a part of the PTFE particles that changes into a fibrous shape is also defined as "fibrillated PTFE". The method for fibrillating PTFE is not particularly limited, and it can be carried out using known means capable of applying a shearing force to PTFE.

[0042] Step 3 may also include forming the mixture into a film shape. As a method of forming the mixture into a film shape while fibrillating PTFE, calendering using a roll press can be cited.

[0043] In Step 3, the fibrillation of PTFE is carried out at a temperature of 50°C or higher. The above temperature is the temperature of the device used for fibrillating PTFE. For example, when using a roll press to carry out the fibrillation of PTFE, the above temperature is the surface temperature of the roll.

[0044] The fibrillation of PTFE is preferably carried out at a temperature of 100°C or higher, more preferably at a temperature of 130°C or higher, and further preferably at a temperature of 150°C or higher. As shown in the examples described later, by performing fibrillation of PTFE at a temperature of 50°C or higher, the tensile strength of the electrode film is increased. As a reason therefor, it is considered that, for example, while the fibrillation of PTFE is promoted, softening or melting of PVdF occurs, and at least a part of the fibrillated PTFE adheres to the active material particles through the softened or melted PVdF.

[0045] The fibrillation of PTFE is preferably performed at a temperature of 200°C or lower, more preferably at a temperature of 180°C or lower, and further preferably at a temperature of 160°C or lower. As shown in the examples described later, by performing fibrillation of PTFE at a temperature of 200°C or lower, the tensile strength of the electrode film is maintained well. As a reason therefor, it is considered that, for example, softening or melting of PVdF occurs moderately, so that the fibrillated PTFE adheres to the active material particles moderately, and the stretchability of the obtained electrode film is maintained well.

[0046] When the mixture is formed into a film shape in Step 3, the thickness of the formed body is not particularly limited and can be adjusted according to the desired thickness of the electrode film. For example, the thickness of the formed body (i.e., the thickness of the electrode film) can be selected from the range of 50 μm to 300 μm.

[0047] From the viewpoint of increasing the tensile strength of the electrode film, the fibrillated PTFE obtained in Step 3 preferably exists in the electrode film at a high density. For example, when a straight line having a length of 20 μm is arranged at an arbitrary position in the cross-sectional image of the electrode film, the number of fibrous PTFE intersecting with the straight line is preferably 5 or more. The number of fibrous PTFE intersecting with the straight line having a length of 20 μm is more preferably 10 or more, and further preferably 20 or more. The cross-sectional image of the electrode film preferably includes at least one region where the number of fibrous PTFE intersecting with a straight line having a length of 20 μm is 5 or more, 10 or more, or 20 or more. Regarding the size of the cross-sectional image of the electrode film, the width direction is preferably 40 μm or more, and the thickness direction is preferably 40 μm or more. The cross-sectional image of the electrode film is obtained by using a known means such as a transmission electron microscope (TEM). The magnification of the cross-sectional image of the electrode film is not particularly limited as long as the fibrillated PTFE can be sufficiently observed.

[0048] The electrode film obtained by the method of the present disclosure can also be integrated with a current collector. The method of integrating the electrode with the current collector is not particularly limited and can be implemented using known means. For example, a roll press, a flat press, etc. can be used to press-bond the electrode film to the current collector. The material of the current collector is not particularly limited and can be selected from known materials such as aluminum, copper, nickel, titanium, stainless steel, etc.

[0049] <Electrode film> The electrode film of the present disclosure includes: active material particles; PVdF attached to the active material particles; and fibrous PTFE.

[0050] The electrode film of the present disclosure can be manufactured, for example, by the above-described method for manufacturing an electrode film. For the details and preferred modes of the electrode film of the present disclosure and each material included in the electrode film, reference can be made to the details and preferred modes of the electrode film manufactured by the above-described method for manufacturing an electrode film or each material included in the electrode film.

[0051] Regarding the electrode film, preferably, at least a part of the fibrous polytetrafluoroethylene is attached to the active material particles.

[0052] The tensile strength of the electrode film is not particularly limited and can be selected according to the type of battery to which the electrode film is applied, etc. For example, the tensile strength of the electrode film can be 0.4 MPa or more, 0.5 MPa or more, or 0.6 MPa or more. If the tensile strength of the electrode film is 0.5 MPa or more, there is a tendency that damage such as cracks is unlikely to occur during the manufacturing process of the electrode film. The tensile strength of the electrode film is measured by the method described in the examples.

[0053] <Battery> The battery of the present disclosure includes the above-described electrode film of the present disclosure. The battery of the present disclosure, for example, includes an electrode body having a laminated structure, and the laminated structure includes a positive electrode and a negative electrode, and a spacer disposed between the positive electrode and the negative electrode as needed. An example of the laminated structure of the electrode body is schematically shown in Figure 1 . Figure 1 The laminated structure 100 of the electrode body shown is composed of a positive electrode 10, a negative electrode 20, and a spacer 30 disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10 is composed of a positive electrode active material layer 10A and a positive electrode current collector 10B. The negative electrode 20 is composed of a negative electrode active material layer 20A and a negative electrode current collector 20B.

[0054] The electrode film is included in the battery as the active material layer of the electrode. The electrode film can be included in the battery either as either the positive electrode active material layer or the negative electrode active material layer, or as both the positive electrode active material layer and the negative electrode active material layer.

[0055] There is no particular limitation on the type of the battery of the present disclosure, and it can be selected from lithium ion secondary batteries (including liquid batteries and all-solid-state batteries), lead storage batteries, nickel / hydrogen storage batteries, nickel / cadmium storage batteries, nickel / iron storage batteries, nickel / zinc storage batteries, silver oxide / zinc storage batteries, cobalt titanium lithium secondary batteries, sodium ion secondary batteries, and other batteries.

[0056] When the battery includes a spacer, there is no particular limitation on the type of the spacer, and known spacers can be used. Specifically, as the spacer, non-woven fabrics, fabrics, microporous membranes, etc. mainly composed of polyolefins such as polyethylene and polypropylene can be cited. There is no particular limitation on the thickness of the spacer, and for example, it can be selected from the range of 5 μm to 50 μm.

[0057] Hereinafter, the present disclosure will be further described in detail by way of examples, but the present disclosure is not limited to these examples.

[0058] (Fabrication of Electrode Film) Graphite particles (volume average particle diameter: 20 μm, 92.2 mass parts) as active material particles and PVdF (4.8 mass parts) were put into an MP mixer (Nippon Coke & Engineering Co., Ltd.), and a compounding treatment for attaching PVdF to the surface of the graphite particles was carried out under the conditions of 10,000 rpm and 2 minutes.

[0059] PTFE (3 mass parts) was further put into the MP mixer after the compounding treatment, and mixing was carried out under the conditions of 300 rpm and 180 seconds. Next, mixing was further carried out under the conditions of 5,000 rpm and 500 seconds to form a granulated body in a state where the graphite particles were bonded by fibrillated PTFE.

[0060] The mixture containing the granulated body was subjected to a rolling treatment (linear pressure: 0.4 t / cm, without cooling water) using a roll press to fibrillate PTFE and form it into a film shape, thereby obtaining an electrode film. The rolling treatment was carried out at temperatures of 25°C, 50°C, 100°C, 150°C, 160°C, 170°C, 180°C, and 200°C, respectively.

[0061] (Measurement of Tensile Strength) A test piece with the dimensions shown in Table 1 was fabricated from the obtained electrode film. For this test piece, a test of stretching at a speed of 2 mm / s was carried out using a texture analyzer (Eihong Seiki Co., Ltd.). Based on the maximum value (F) of the load applied to the test piece, the tensile strength was calculated according to the following formula. The results are shown in Table 1. Tensile strength (MPa) = F (g) × 0.0098 / (thickness (mm) × width (mm)) Table 1

[0062] As shown in Table 1, the electrode film obtained by performing calendering at a temperature of 50 °C or higher exhibited a higher tensile strength than the electrode film obtained by performing calendering at a temperature of less than 50 °C. Among the electrode films obtained by performing calendering at a temperature of 50 °C or higher, the electrode film obtained by performing calendering at a temperature of 160 °C to 190 °C exhibited a particularly high tensile strength.

[0063] (Electron microscope observation of the electrode film) The SEM image of the cross-section of the electrode film obtained by performing calendering at 150 °C is shown in Figure 2 . As Figure 2 shown, in the cross-section of the electrode film obtained by performing calendering at 150 °C, fibrous PTFE was observed, and a situation where a part of it adhered to graphite particles was also observed. In addition, the coating rate of PVdF on the surface of the graphite particles measured by EDX was 10% or more. Figure 2 The SEM image shown contains a region where 20 or more fibrillated PTFEs intersecting a straight line with a length of 20 μm were observed.

Claims

1. A method for manufacturing an electrode film, characterized in that: include: attaching polyvinylidene fluoride to active material particles; mixing the active material particles to which polyvinylidene fluoride is attached with polytetrafluoroethylene to obtain a mixture; and The polytetrafluoroethylene in the mixture is fiberized, wherein the fiberization is carried out at a temperature above 50°C, The mixture contains no solvent.

2. The method for manufacturing an electrode film according to claim 1, characterized in that: The fiberization is performed at a temperature of 100° C. or higher.

3. The method for manufacturing an electrode film according to claim 1 or 2, characterized in that: The fiberization is performed at a temperature of 200° C. or lower.

4. The method for manufacturing an electrode film according to claim 1 or 2, characterized in that: The fiberization is performed at a temperature of 180° C. or lower.

5. The method for manufacturing an electrode film according to claim 1 or 2, characterized in that: The fiberizing includes forming the mixture into a film shape.

6. The method for manufacturing an electrode film according to claim 1, characterized in that: The amount of polyvinylidene fluoride relative to the active material particles is 1 mass % or more and 10 mass % or less relative to 100 parts by mass of the active material particles.

7. The method for manufacturing an electrode film according to claim 1, characterized in that: The amount of polytetrafluoroethylene relative to the active material particles is 1 mass % or more and 10 mass % or less relative to 100 parts by mass of the active material particles.

8. An electrode membrane, characterized in that: Include: Active material particles; polyvinylidene fluoride attached to the active material particles; and Fibrous polytetrafluoroethylene.

9. The electrode film according to claim 8, characterized in that The number of fibrous polytetrafluoroethylene fibers intersecting a straight line having a length of 20 μm arranged at an arbitrary position in the cross-sectional image of the electrode film is 5 or more.

10. The electrode film according to claim 9, characterized in that The number of fibrous polytetrafluoroethylene fibers intersecting the straight line is 20 or more.

11. The electrode membrane according to any one of claims 8 to 10, characterized in that At least a portion of the fibrous polytetrafluoroethylene adheres to the active material particles.

12. The electrode membrane according to any one of claims 8 to 10, characterized in that The coverage rate of the polyvinylidene fluoride on the surface of the active material particles is 5% or more.

13. A battery, characterized in that: An electrode film comprising the electrode film according to any one of claims 8 to 10.

Images