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CN-122000289-A - Negative plate, preparation method and battery

CN122000289ACN 122000289 ACN122000289 ACN 122000289ACN-122000289-A

Abstract

The invention provides a negative plate, a preparation method and a battery, wherein the negative plate comprises a negative current collector, an active material layer is arranged on the surface of the negative current collector, the active material layer comprises a negative active material and a binder, the binder is used for binding adjacent negative active materials, the negative active material comprises silicon-containing particles, and a conductive carbon layer is arranged on the surface of the active material layer far away from the negative current collector, the conductive carbon layer forms a continuous layer on the surface of the adjacent negative active material and the surface of the binder between the adjacent negative active material and the surface of the binder.

Inventors

  • Pu Hushan
  • XIAO FENG
  • HU DALIN
  • LIAO XINGQUN

Assignees

  • 深圳市豪鹏科技股份有限公司

Dates

Publication Date
20260508
Application Date
20251231

Claims (12)

  1. 1. A negative electrode sheet comprising A negative electrode current collector; an active material layer provided on a surface of the negative electrode current collector, the active material layer including a negative electrode active material and a binder for binding adjacent negative electrode active materials including silicon-containing particles, and And the conductive carbon layer is arranged on the surface, far away from the negative electrode current collector, of the active material layer, and forms a continuous layer on the surface of the adjacent negative electrode active material and the surface of the adhesive between the adjacent negative electrode active material and the surface of the conductive carbon layer.
  2. 2. The negative electrode sheet according to claim 1, wherein the active material layer has a porosity of 20% to 50%.
  3. 3. The negative electrode sheet according to claim 2, wherein the conductive carbon layer is formed on the surface of the active material layer by chemical vapor deposition.
  4. 4. The negative electrode sheet according to claim 3, wherein the carbon source gas used in the chemical vapor deposition process includes one or more of methane, acetylene, ethylene, and propylene.
  5. 5. The negative electrode sheet according to claim 3, wherein the reaction temperature of the chemical vapor deposition process is 500 ℃ to 900 ℃.
  6. 6. The negative electrode sheet according to claim 1, wherein the conductive carbon layer has a thickness of 0.5-5 μm.
  7. 7. The negative electrode sheet of claim 1, wherein the silicon-containing particles comprise one or more of silicon particles, silicon oxide, and silicon carbon materials.
  8. 8. The negative electrode sheet according to claim 7, wherein the silicon-containing particles are selected from silicon-carbon materials, and the mass content of silicon in the silicon-carbon materials is 40% -60%.
  9. 9. The negative electrode sheet of claim 1, wherein the binder comprises one or more of polyimide, phenolic resin, polyacrylonitrile, polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, polyvinyl alcohol, epoxy resin, polybenzoxazole, polyaryletherketone, pitch-based precursor, lignin or derivatives thereof.
  10. 10. The negative electrode sheet according to claim 1, wherein the silicon-containing particles account for 91 to 94% by mass of the active material layer, and the binder accounts for 6 to 9% by mass of the active material layer, based on 100% by mass of the active material layer.
  11. 11. The method for producing a negative electrode sheet according to any one of claims 1 to 10, comprising the steps of: Forming the active material layer on the surface of the negative electrode current collector; And forming the conductive carbon layer on the surface of the active material layer in a chemical vapor deposition mode.
  12. 12. A battery, comprising a positive plate, a negative plate and a diaphragm, wherein the negative plate is the negative plate according to any one of claims 1 to 10 or the negative plate prepared by the preparation method of the negative plate according to claim 11.

Description

Negative plate, preparation method and battery Technical Field The invention relates to the technical field of batteries, in particular to a negative plate, a preparation method and a battery. Background In the field of lithium ion batteries, especially in applications facing high energy density requirements (e.g., electric vehicles, consumer electronics), silicon-carbon materials are considered as important candidates for next-generation negative electrodes due to their high theoretical specific capacities (e.g., pure silicon up to about 4200 mAh/g). However, silicon-containing materials have severe volume expansion (up to 300% or more) during charge and discharge, resulting in pulverization of particles, collapse of electrode structures, repeated rupture and regeneration of Solid Electrolyte Interface (SEI) films, thereby causing rapid capacity decay and shortened cycle life. In order to alleviate the above problems, the prior art generally adopts a silicon-carbon composite material as a negative electrode active material, and a conductive additive (such as carbon black, conductive graphite, carbon nanotube CNT or graphene) is directly mixed into the slurry to improve the overall conductivity of the electrode. The typical process flow comprises mixing silicon-containing particles, conductive agent and binder in proportion, pulping, coating on copper foil current collector, drying, and rolling to obtain the negative plate. However, the conventional scheme has the remarkable disadvantages that the conductive agent is unevenly dispersed to form a local dead zone, the conductive agent (particularly nano-scale materials such as CNTs) is extremely easy to agglomerate, uniform dispersion is difficult to realize in the slurry, partial active particles are not effectively connected, an electron transmission dead zone is formed, and the material utilization rate is reduced. Even if the conductive agent is distributed perfectly, the conductive agent is still mainly in point-to-point contact with the active particles, the contact area is small, the interface resistance is high, the contact failure is easy to occur under the condition of high current or long circulation, and in order to ensure sufficient conductivity, 5-10wt% or higher conductive agent is usually added, so that the proportion of active materials is directly diluted, the whole specific capacity of the electrode and the energy density of the battery are reduced, and therefore, how to overcome the technical problems and defects are important to solve becomes the problem. Disclosure of Invention Aiming at the problem that negative electrode active particles in the existing silicon negative electrode plate are not effectively connected, the invention provides a negative electrode plate, a preparation method and a battery. The technical scheme adopted by the invention for solving the technical problems is as follows: the first aspect of the present invention provides a negative electrode sheet comprising A negative electrode current collector; an active material layer provided on a surface of the negative electrode current collector, the active material layer including a negative electrode active material and a binder for binding adjacent negative electrode active materials including silicon-containing particles, and And the conductive carbon layer is arranged on the surface, far away from the negative electrode current collector, of the active material layer, and forms a continuous layer on the surface of the adjacent negative electrode active material and the surface of the adhesive between the adjacent negative electrode active material and the surface of the conductive carbon layer. Optionally, the active material layer has a porosity of 20% -50%. Optionally, the conductive carbon layer is formed on the surface of the active material layer by chemical vapor deposition. Optionally, the carbon source gas used in the chemical vapor deposition process comprises one or more of methane, acetylene, ethylene, and propylene. Optionally, the reaction temperature of the chemical vapor deposition process is 500-900 ℃. Optionally, the conductive carbon layer has a thickness of 0.5-5 μm. Optionally, the silicon-containing particles comprise one or more of silicon particles, silicon oxide, and silicon carbon materials. Optionally, the silicon-containing particles are selected from silicon-carbon materials, and the mass content of silicon in the silicon-carbon materials is 40% -60%. Optionally, the binder comprises one or more of polyimide, phenolic resin, polyacrylonitrile, polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene-butadiene rubber, polyacrylic acid, polyvinyl alcohol, epoxy resin, polybenzoxazole, polyaryletherketone, pitch precursor, lignin or derivatives thereof. Optionally, the total mass of the active material layer is 100%, the silicon-containing particles account for 91% -94% of the mass of the active material layer, and the binder accoun