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CN-122026006-A - Battery diaphragm, preparation method thereof and battery

CN122026006ACN 122026006 ACN122026006 ACN 122026006ACN-122026006-A

Abstract

The application provides a battery diaphragm, a preparation method thereof and a battery. The battery diaphragm comprises a substrate layer, a crosslinking layer crosslinked on two surfaces of the substrate layer and a heat-resistant coating coated on at least one surface of the crosslinking layer, wherein the crosslinking layer comprises a crosslinking polymer which is obtained by polymerizing monomers, and the monomers at least comprise four groups including unsaturated bonds, phenyl groups, amino groups or imino groups and hydroxyl groups. The battery diaphragm provided by the application has proper closed pore temperature, good puncture strength, heat resistance and wettability, and the peel strength of the heat-resistant coating is high, so that the battery comprising the battery diaphragm provided by the application has good cycle performance and safety performance.

Inventors

  • GAI JIANLI

Assignees

  • 中材锂膜有限公司

Dates

Publication Date
20260512
Application Date
20260318
Priority Date
20251231

Claims (10)

  1. 1. A battery separator comprising a substrate layer, a crosslinked layer crosslinked on both surfaces of the substrate layer, and a heat-resistant coating layer coated on at least one surface of the crosslinked layer; the crosslinked layer comprises a crosslinked polymer obtained by polymerizing monomers at least comprising four groups of unsaturated bonds, phenyl groups, amino groups or imino groups, and hydroxyl groups.
  2. 2. The battery separator of claim 1, wherein the monomer is selected from at least one of the following compounds: 、 、 、 、 、 、 。
  3. 3. The battery separator according to claim 1, wherein the sum of the mass of the crosslinking layer and the substrate layer is increased by 0.1 to 15% relative to the mass of the substrate layer.
  4. 4. The battery separator according to claim 1, wherein the heat-resistant coating layer comprises, in parts by mass, 90 to 120 parts of ceramic particles selected from at least one of silica, alumina, magnesia, zirconia, titania, calcium oxide, boehmite, aluminum nitride, boron nitride, barium sulfate, barium titanate, calcium fluoride, and barium fluoride, 0.1 to 10 parts of a binder selected from at least one of carboxymethyl cellulose, polyacrylates, polyurethane, polyacrylamide, polyacrylic acid, and derivatives thereof, 0.1 to 10 parts of a thickener selected from at least one of sodium alginate, cellulose, natural gum, starch, and 0.1 to 10 parts of a dispersant selected from at least one of polyvinyl alcohol, acrylate copolymer, polyethylene glycol octylphenyl ether, polyvinylpyrrolidone, polyacrylic acid, cellulose.
  5. 5. A method of producing the battery separator according to any one of claims 1 to 4, comprising the steps of: Dissolving the monomer in a solvent to obtain a monomer solution; mixing an initiator with the monomer solution to obtain a precursor solution; carrying out surface irradiation on the substrate layer, then soaking the substrate layer into the precursor liquid, taking out the substrate layer through a roller, and obtaining a modified substrate layer through solidification, cleaning, drying and heat setting; Uniformly mixing the ceramic particles, the binder, the thickener and the dispersant with water to obtain heat-resistant coating slurry; and coating the heat-resistant coating slurry on at least one surface of the modified substrate layer, and drying to obtain the battery diaphragm.
  6. 6. The preparation method according to claim 5, wherein the solvent is selected from polar solvents, and the concentration of the monomer solution is 2wt% to 45wt%, preferably 5wt% to 35wt%.
  7. 7. The preparation method according to claim 5, wherein the mass ratio of the initiator to the monomer is 0.001:1 to 0.1:1, preferably the mass ratio of the initiator to the monomer is 0.002:1 to 0.02:1.
  8. 8. The production method according to any one of claims 5 to 7, wherein the initiator is at least one selected from benzoin ethers, α -hydroxy ketones, acetophenone derivatives, acylphosphine oxides, benzophenone, thioxanthones, and anthraquinones.
  9. 9. The production method according to any one of claims 5 to 7, which satisfies any one of the following characteristics: (1) The surface irradiation dose is 0.1 MGy-2 MGy.
  10. 10. A battery comprising the battery separator of any one of claims 1 to 4.

Description

Battery diaphragm, preparation method thereof and battery Technical Field The application relates to the technical field of electrochemistry, in particular to a battery diaphragm, a preparation method thereof and a battery. Background In the battery, the separator plays a core role of separating the positive electrode from the negative electrode to prevent short circuit and ensure smooth migration of ions, and the performance of the separator directly influences the safety, the cycling stability and the like of the battery. However, conventional separators still have significantly short plates in practical applications, such as insufficient puncture resistance, low peel strength of the coating from the base film, poor heat resistance, poor wettability of the separator to the electrolyte, and the like. In order to improve the above properties of the separator, the preparation of the separator by irradiation graft-blending extrusion has been developed in the prior art, and although the above properties of the separator are improved to some extent, the closed cell temperature thereof is increased, resulting in a decrease in the safety performance of the battery. Therefore, how to improve the puncture strength, heat resistance and wettability of the separator and the peel strength of the coating and the base film without affecting the closed pore temperature of the separator is a technical problem to be solved. Disclosure of Invention The application aims to provide a battery diaphragm, a preparation method thereof and a battery, and the battery diaphragm can improve the puncture strength, heat resistance and wettability of the battery diaphragm and the peeling strength of a heat-resistant coating on the premise of not influencing the closed pore temperature of the battery diaphragm, so that the cycle performance and the safety performance of the battery are improved. The specific technical scheme is as follows: the first aspect of the application provides a battery separator, which comprises a substrate layer, a crosslinking layer crosslinked on two surfaces of the substrate layer and a heat-resistant coating coated on at least one surface of the crosslinking layer, wherein the crosslinking layer comprises a crosslinking polymer obtained by polymerizing monomers, and the monomers at least comprise four groups including unsaturated bonds, phenyl groups, amino groups or imino groups and hydroxyl groups. In some embodiments of the application, the monomer is selected from at least one of the following compounds: 、、、、、、。 in some embodiments of the application, the sum of the mass of the crosslinked layer and the substrate layer is increased by 0.1% -15% relative to the mass of the substrate layer. In some embodiments of the present application, the heat-resistant coating layer includes 90 to 120 parts by mass of ceramic particles, 0.1 to 10 parts by mass of a binder, 0 to 10 parts by mass of a thickener, and 0.1 to 10 parts by mass of a dispersant, wherein the ceramic particles are selected from at least one of silica, alumina, magnesia, zirconia, titania, calcium oxide, boehmite, aluminum nitride, boron nitride, barium sulfate, barium titanate, calcium fluoride and barium fluoride, the binder is selected from at least one of carboxymethyl cellulose, polyacrylates, polyurethane, polyacrylamide, polyacrylic acid and derivatives thereof, the thickener is selected from at least one of sodium alginate, cellulose, natural gum, starch, and the dispersant is selected from at least one of polyvinyl alcohol, acrylate copolymer, polyethylene glycol octyl phenyl ether, polyvinylpyrrolidone, polyacrylic acid, cellulose. The second aspect of the application provides a preparation method of the battery separator provided by the first aspect of the application, which comprises the following steps: Dissolving the monomer in a solvent to obtain a monomer solution; mixing an initiator with the monomer solution to obtain a precursor solution; carrying out surface irradiation on the substrate layer, then soaking the substrate layer into the precursor liquid, taking out the substrate layer through a roller, and obtaining a modified substrate layer through solidification, cleaning, drying and heat setting; Uniformly mixing the ceramic particles, the binder, the thickener and the dispersant with water to obtain heat-resistant coating slurry; and coating the heat-resistant coating slurry on at least one surface of the modified substrate layer, and drying to obtain the battery diaphragm. In some embodiments of the application, the solvent is selected from polar solvents, and the monomer solution has a concentration of 2wt% to 40wt%. In some embodiments of the present application, the mass ratio of the initiator to the monomer is 0.001:1 to 0.1:1, preferably the mass ratio of the initiator to the monomer is 0.002:1 to 0.02:1. In some embodiments of the application, the initiator is selected from at least one of benzoin ethers, alpha-hydrox