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CN-120072886-B - Positive electrode material, preparation method and battery

CN120072886BCN 120072886 BCN120072886 BCN 120072886BCN-120072886-B

Abstract

The application provides a positive electrode material, a preparation method and a battery, wherein the positive electrode material comprises an active substance, a first shell layer coated on the surface of the active substance and a second shell layer coated on the surface of the first shell layer, the active substance comprises transition metal, the first shell layer comprises a first polymer, the first polymer has fluorine substituted aromatic groups, the second shell layer comprises a second polymer, and the second polymer has at least one group selected from amino groups, acyl groups and amide groups. The first polymer has good conductivity and can inhibit the dissolution of transition metal, and the functional groups in the second polymer can capture transition metal ions, so that the dissolution of transition metal is further inhibited. The double-coating structure combining the first shell layer and the second shell layer can improve the overall conductivity of the positive electrode material and reduce the problems of voltage attenuation and circulation variation caused by metal dissolution.

Inventors

  • Tian Diewen
  • LI YUNMING
  • HU JIANWEI
  • QIU CHENGYU
  • LIU XINTONG

Assignees

  • 蜂巢能源科技股份有限公司

Dates

Publication Date
20260512
Application Date
20250212

Claims (9)

  1. 1. The positive electrode material is characterized by comprising an active substance, a first shell layer coated on the surface of the active substance and a second shell layer coated on the surface of the first shell layer; The active material comprises any one of lithium-rich manganese-based layered oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide or lithium cobalt oxide; the first shell layer comprises a first polymer, and the first polymer comprises at least one of poly 3-fluorothiophene and poly 3, 4-difluorothiophene; The second shell layer comprises a second polymer, and the second polymer comprises at least one of polyethylenimine and polypropylenimine.
  2. 2. The positive electrode material according to claim 1, wherein the mass ratio of the active material to the first polymer to the second polymer is 220-250:1000-5000:40-400.
  3. 3. The positive electrode material according to claim 1, wherein the first polymer has a molecular weight of 1000 to 5000 and/or, The molecular weight of the second polymer is 40-400.
  4. 4. The positive electrode material according to claim 1, wherein the amount of metal eluted after the positive electrode material is circulated is 0 to 400ppm.
  5. 5. The positive electrode material according to claim 1, wherein the active material has a particle diameter of 4000 to 10000nm and/or, The thickness of the first shell layer is 150-400 nm, and/or, The thickness of the second shell layer is 50-200 nm.
  6. 6. A method for preparing the positive electrode material according to any one of claims 1 to 5, comprising the steps of: Mixing an active substance with a first monomer, and performing polymerization reaction to obtain an active substance coated by a first shell layer, wherein the first monomer contains an aryl substituted by fluorine; and mixing the active material coated by the first shell layer with a second polymer, and dispersing to obtain the positive electrode material.
  7. 7. The method of claim 6, wherein the mass ratio of the active material to the first monomer is 220-250:80-120, and/or, The mass ratio of the active substance coated by the first shell layer to the second polymer is 220-250:40-400, and/or, The first monomer comprises at least one of 3-fluorothiophene and 3, 4-difluorothiophene.
  8. 8. The method for producing a positive electrode material according to claim 6, wherein the step of polymerizing is performed in a first solution, the mass percentage of the first monomer in the first solution is 0.8 to 1.6wt%, and/or, The polymerization reaction time is 10-24 hours, and/or, The dispersing step is carried out in a second solution, the mass percentage of the second polymer in the second solution is 1-5wt%, and/or, The dispersing time is 10-60 min.
  9. 9. A battery comprising a positive electrode sheet, characterized in that the positive electrode sheet comprises the positive electrode material according to any one of claims 1 to 5 or comprises the positive electrode material produced by the production method according to any one of claims 6 to 8.

Description

Positive electrode material, preparation method and battery Technical Field The application belongs to the technical field of battery materials, and particularly relates to a positive electrode material, a preparation method and a battery. Background With the rapid development of electric devices such as electric vehicles and energy storage facilities, the demand for lithium ion batteries with high energy density is increasing. The transition metal oxide is a novel lithium battery anode material, can generate reversible oxidation-reduction reaction of anions and cations, and has extremely high potential in the direction of developing high-energy-density lithium batteries. However, the electron conductivity of the transition metal oxide is low, and the electrochemical rate performance is greatly affected by the dissolution of the transition metal, and the low rate cycle can lead to gradient dissolution of the transition metal and serious structural degradation inside the secondary particles and the generation of a large number of microcracks, resulting in rapid decay of capacity and voltage, which makes commercial application of some transition metal materials difficult. Therefore, how to improve the electrochemical performance of the transition metal material is a problem that needs to be solved at present. Disclosure of Invention The application provides a positive electrode material, a preparation method and a battery, and aims to solve the problem that the battery made of the existing transition metal material is not ideal in cycle performance. The first embodiment of the application provides a positive electrode material, which comprises an active substance, a first shell layer coated on the surface of the active substance and a second shell layer coated on the surface of the first shell layer, wherein the active substance comprises transition metal, the first shell layer comprises a first polymer, the first polymer is provided with fluorine substituted aromatic groups, the second shell layer comprises a second polymer, and the second polymer is provided with at least one group selected from amino groups, acyl groups or amide groups. In some embodiments, the mass ratio of the active material, the first polymer, and the second polymer is 220-250:1000-5000:40-400. In some embodiments, the first polymer has a molecular weight of 1000 to 5000. In some embodiments, the second polymer has a molecular weight of 40 to 400. In some embodiments, the metal elution amount of the positive electrode material after circulation is 0-400 ppm. In some embodiments, the particle size of the active material is 4000-10000 nm. In some embodiments, the thickness of the first shell layer is 150-400 nm. In some embodiments, the thickness of the second shell layer is 50-200 nm. In some embodiments, the active material comprises any one of lithium-rich manganese-based layered oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, or lithium cobalt oxide. In some embodiments, the first polymer comprises at least one of poly 3-fluorothiophene, poly 3, 4-difluorothiophene. In some embodiments, the second polymer comprises at least one of polyethylenimine, polypropylenimine. A second embodiment of the present application provides a method for preparing a positive electrode material, for preparing the positive electrode material in any of the above embodiments, including the steps of: Mixing an active substance with a first monomer, and performing polymerization reaction to obtain an active substance coated by a first shell layer, wherein the first monomer contains an aryl substituted by fluorine; And mixing the active material coated by the first shell layer with the second polymer, and dispersing to obtain the positive electrode material. In some embodiments, the mass ratio of the active material to the first monomer is 220-250:80-120. In some embodiments, the mass ratio of the active material coated by the first shell layer to the second polymer is 220-250:40-400. In some embodiments, the first monomer comprises at least one of 3-fluorothiophene, 3, 4-difluorothiophene. In some embodiments, the step of polymerizing is performed in a first solution, and the mass percentage of the first monomer in the first solution is 0.8-1.6wt%. In some embodiments, the polymerization reaction time is 12 to 24 hours. In some embodiments, the dispersing step is performed in a second solution, and the mass percentage of the second polymer in the second solution is 1-5wt%. In some embodiments, the dispersing time is 10-60 min. A third embodiment of the present application provides a battery comprising a positive electrode sheet comprising the positive electrode material of any of the above embodiments. The application provides a positive electrode material which comprises an active substance, a first shell layer coated on the surface of the active substance and a second shell layer coated on the surface of the first shell layer,