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CN-122025577-A - Composite positive electrode active material, preparation method thereof, composite positive electrode plate, solid-state battery and electric equipment

CN122025577ACN 122025577 ACN122025577 ACN 122025577ACN-122025577-A

Abstract

The application provides a composite positive electrode active material and a preparation method thereof, a composite positive electrode plate, a solid-state battery and electric equipment, and relates to the technical field of batteries. The lithium phosphate nano particles doped with rare earth elements are adopted to modify the active material core, so that the problems of structural stability and interface ion transmission of the active material core can be solved, the modified composite positive electrode active material can synchronously realize structural stability, interface optimization and interface side reaction inhibition, and the triple functions of inhibiting volume expansion of the active material core, improving interface ion conductivity and blocking diffusion of transition metal ions are achieved, and further, the energy density, the cycling stability and the safety of a solid-state battery applying the composite positive electrode active material can be improved.

Inventors

  • ZHAO WANLI
  • DAI YIJUN
  • HUA CONGCONG
  • ZHOU XINAN
  • ZHANG QI

Assignees

  • 浙江绿色智行科创有限公司
  • 浙江吉利控股集团有限公司

Dates

Publication Date
20260512
Application Date
20260123

Claims (10)

  1. 1. The composite positive electrode active material is characterized by comprising an active material inner core and a first coating layer coated on at least part of the surface of the active material inner core, wherein the first coating layer comprises rare earth element doped lithium phosphate nano particles; the rare earth element comprises one or more of Y, nd and La.
  2. 2. The composite positive electrode active material according to claim 1, wherein the doping molar amount of the rare earth element is 0.5% to 2% of the molar amount of the lithium phosphate nanoparticle.
  3. 3. The composite positive electrode active material according to claim 1, wherein the particle diameter D50 of the lithium phosphate nanoparticle is 50nm to 100nm.
  4. 4. The composite positive electrode active material according to any one of claims 1 to 3, further comprising a second coating layer coated on at least a part of the surface of the active material core, wherein the first coating layer is coated on at least a part of the surface of the second coating layer; the second cladding layer comprises alumina and/or zirconia.
  5. 5. A composite positive electrode active material according to any one of claims 1 to 3, wherein the active material core comprises lithium nickel cobalt manganate, or a composite core formed by compositing lithium cobalt oxide and lithium manganate.
  6. 6. A production method for producing the composite positive electrode active material according to any one of claims 1 to 5, characterized by comprising: Dispersing rare earth element doped lithium phosphate nano particles and active material cores coated with a second coating layer in a solvent according to a certain mass percentage, carrying out ultrasonic dispersion treatment, and sequentially carrying out vacuum drying, molding and sintering to obtain the composite anode active material.
  7. 7. The preparation method according to claim 6, wherein the mass percentage of the rare earth element doped lithium phosphate nanoparticle and the active material core coated with the second coating layer is 1% to 99% to 10% to 90%.
  8. 8. A composite positive electrode sheet comprising a positive electrode current collector and a composite positive electrode active material layer comprising the composite positive electrode active material according to any one of claims 1 to 5, or comprising the composite positive electrode active material prepared by the preparation method according to claim 6 or 7.
  9. 9. A solid-state battery comprising a negative electrode sheet, a solid-state electrolyte layer, and the composite positive electrode sheet according to claim 8, wherein the solid-state electrolyte layer is disposed between the negative electrode sheet and the composite positive electrode sheet.
  10. 10. A powered device comprising a solid state battery as defined in claim 9.

Description

Composite positive electrode active material, preparation method thereof, composite positive electrode plate, solid-state battery and electric equipment Technical Field The application relates to the technical field of batteries, in particular to a composite positive electrode active material, a preparation method thereof, a composite positive electrode plate, a solid-state battery and electric equipment. Background The solid-state battery can effectively solve the safety problems of liquid lithium battery leakage, inflammability, thermal runaway and the like due to the fact that the solid-state electrolyte is adopted to replace the traditional liquid electrolyte, can be matched with a lithium metal (Li) negative electrode, greatly improves battery energy density, and becomes the core development direction of the next-generation power battery. However, industrialization of all-solid-state batteries still faces a key technical bottleneck of the positive electrode link, on one hand, positive electrode active materials (such as lithium nickel cobalt manganese oxide (Nickel Cobalt Manganese Oxide, abbreviated as NCM), lithium cobalt oxide (Lithium Cobalt Oxide, abbreviated as LCO) and the like) are easy to undergo volume expansion (the expansion rate can reach 5% -10%) in the charge and discharge process, so that the internal structure of the positive electrode plate is cracked to damage an ion transmission channel, and on the other hand, severe interface impedance (usually >1000Ω & cm < 2 >) exists between the positive electrode active materials and the solid electrolyte, and interface side reactions (such asInterdiffusion with transition metal ions) to form a high impedance interfacial phase (e.g.、) Resulting in rapid degradation of the solid-state battery capacity. In the related art, problems with the positive electrode sheet described above are focused on single function optimization. Specifically, for example, by coating the surface of the positive electrode active material、Such as to inhibit interfacial side reactions, but which tends to increase ion transport resistance, or by increasing the solid electrolyte content to reduce interfacial resistance, but which can result in a decrease in the positive electrode active material ratio, sacrificing solid state battery energy density. Therefore, developing a multifunctional composite positive electrode active material capable of synchronously realizing volume expansion inhibition, interface impedance reduction and side reaction reduction is a key for breaking through the performance bottleneck of a solid-state battery. Disclosure of Invention The application provides a composite positive electrode active material and a preparation method thereof, a composite positive electrode plate, a solid-state battery and electric equipment, wherein the composite positive electrode active material has higher ion transmission efficiency and structural stability, and can improve the cycle performance, energy density and safety of the solid-state battery. In a first aspect, the application provides a composite positive electrode active material, which comprises an active material inner core and a first coating layer coated on at least part of the surface of the active material inner core, wherein the first coating layer comprises rare earth element doped lithium phosphate nano particles, and the rare earth elements comprise one or more of Y, nd and La. In a specific embodiment, the rare earth element is doped in a molar amount of 0.5% to 2% of the molar amount of the lithium phosphate nanoparticle. In a specific embodiment, the lithium phosphate nanoparticle has a particle size D50 of 50nm to 100nm. In a specific embodiment, the composite positive electrode active material further comprises a second coating layer coated on at least part of the surface of the active material core, wherein the first coating layer is coated on at least part of the surface of the second coating layer, and the second coating layer comprises alumina and/or zirconia. In a specific embodiment, the active material core comprises lithium nickel cobalt manganese oxide, or a composite core formed by the combination of lithium cobalt oxide and lithium manganese oxide. In a second aspect, the application provides a preparation method for preparing the composite positive electrode active material provided in the first aspect, which comprises dispersing rare earth element doped lithium phosphate nano particles and active material cores coated with a second coating layer in a solvent according to a certain mass percentage, performing ultrasonic dispersion treatment, and sequentially performing vacuum drying, molding and sintering to obtain the composite positive electrode active material. In a specific embodiment, the mass percent of the rare earth element doped lithium phosphate nanoparticle and the active material core coated with the second coating layer is 1% -10% -90%. In a third aspect, the applicatio