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US-20260125277-A1 - POSITIVE ELECTRODE MATERIAL AND PREPARATION METHOD THEREOF, POSITIVE ELECTRODE SHEET AND ALL-SOLID-STATE BATTERY

US20260125277A1US 20260125277 A1US20260125277 A1US 20260125277A1US-20260125277-A1

Abstract

The present application provides a positive electrode material, a preparation method thereof, a positive electrode sheet and an all-solid-state battery. The positive electrode material includes a lithium-rich manganese-based positive electrode active material and a coating layer covering at least part of a surface of the lithium-rich manganese-based positive electrode active material, where a molecular formula of the lithium-rich manganese-based positive electrode active material is xLi 2-α MnO 3 ·( 1 −x)Li 1-β Ni a Co b Mn c O 2-γ , where a+b+c=1, 0<α+β≤0.2, 0<γ≤0.1, and 0<x<1; the coating layer meets the following Formula 1 and Formula 2: 0.5×10 −3 S/cm≤T≤5×10 −3 S/cm Formula 1, H≤10 −9 S/cm Formula 2, where T is an ionic conductivity of the coating layer, and H is an electronic conductivity of the coating layer.

Inventors

  • Jun Peng
  • Jikang LIU
  • Linyan LI
  • Daoyan FENG

Assignees

  • NINGBO RONBAY NEW ENERGY TECHNOLOGY Co.,Ltd.

Dates

Publication Date
20260507
Application Date
20260105
Priority Date
20240306

Claims (20)

  1. 1 . A positive electrode material, comprising a lithium-rich manganese-based positive electrode active material and a coating layer covering at least part of a surface of the lithium-rich manganese-based positive electrode active material, wherein a molecular formula of the lithium-rich manganese-based positive electrode active material is xLi 2-α MnO 3 ·(1−x)Li 1-β Ni a Co b Mn c O 2-γ , and a+b+c=1, 0<α+β≤0.2, 0<γ≤0.1, and 0<x<1; or, the molecular formula of the lithium-rich manganese-based positive electrode active material is xLi 2-α MnO 3 ·(1−x)Li 1-β Ni a Co b Mn c M d O 2-γ , wherein a+b+c+d=1, d>0, 0<α+β≤0.2, 0<γ≤0.1, and 0<x<1; and M is one or more of Mg, Al, Ti, Cr, Zr, Nb, Mo, Ta, W, La and Ce; the coating layer meets the following Formula 1 and Formula 2: 0.5 × 10 - 3 ⁢ S / cm ≤ T ≤ 5 × 1 ⁢ 0 - 3 ⁢ S / cm Formula ⁢ 1 H ≤ 1 ⁢ 0 - 9 ⁢ S / cm Formula ⁢ 2 wherein T is an ionic conductivity of the coating layer, and His an electronic conductivity of the coating layer.
  2. 2 . The positive electrode material according to claim 1 , wherein the coating layer comprises a halide solid electrolyte material.
  3. 3 . The positive electrode material according to claim 2 , wherein a chemical composition of the halide solid electrolyte material is Li d MX e , wherein M is one or more of Ho, Y, Er and Yb, X is Cl or Br, 0<d≤10, and 1≤e≤13.
  4. 4 . The positive electrode material according to claim 2 , wherein a thickness of the coating layer is at nanoscale.
  5. 5 . The positive electrode material according to claim 4 , wherein the thickness of the coating layer is 5 to 80 nm.
  6. 6 . The positive electrode material according to claim 2 , wherein a mass ratio of the coating layer in the positive electrode material is 0.1% to 0.5%.
  7. 7 . The positive electrode material according to claim 3 , wherein a mass ratio of the coating layer in the positive electrode material is 0.1% to 0.5%.
  8. 8 . The positive electrode material according to claim 1 , wherein the coating layer is dense and free of pores, or contains micropores with a pore diameter of not exceeding 5 nm.
  9. 9 . The positive electrode material according to claim 2 , wherein the coating layer is dense and free of pores, or contains micropores with a pore diameter of not exceeding 5 nm.
  10. 10 . The positive electrode material according to claim 3 , wherein the coating layer is dense and free of pores, or contains micropores with a pore diameter of not exceeding 5 nm.
  11. 11 . The positive electrode material according to claim 4 , wherein the coating layer is dense and free of pores, or contains micropores with a pore diameter of not exceeding 5 nm.
  12. 12 . The positive electrode material according to claim 5 , wherein the coating layer is dense and free of pores, or contains micropores with a pore diameter of not exceeding 5 nm.
  13. 13 . The positive electrode material according to claim 6 , wherein the coating layer is dense and free of pores, or contains micropores with a pore diameter of not exceeding 5 nm.
  14. 14 . The positive electrode material according to claim 1 , wherein a specific surface area of the positive electrode material is 0.5 to 1.3 m 2 /g; and/or, a size of single crystal grains of the positive electrode material is 0.7 to 1.5 μm, and a particle diameter of the positive electrode material is 4 to 6 μm.
  15. 15 . The positive electrode material according to claim 2 , wherein a specific surface area of the positive electrode material is 0.5 to 1.3 m 2 /g; and/or, a size of single crystal grains of the positive electrode material is 0.7 to 1.5 μm, and a particle diameter of the positive electrode material is 4 to 6 μm.
  16. 16 . A preparation method of the positive electrode material according to claim 1 , comprising the following steps: 1) mixing an oxide of M, an ammonium salt, a lithium salt and an HX solution, and stirring at 20 to 90° C. to obtain a mixed solution with a pH of 1 to 3; wherein M is one or more of Ho, Y, Er and Yb, and X is Cl or Br; 2) immersing a lithium-rich manganese-based material into the mixed solution, standing for 1 to 5 min, and drying to obtain a precursor; and 3) in a protective atmosphere, heating the precursor to 400 to 600° C. at a heating rate of 1 to 10° C./min, and holding for 4 to 6 h to obtain the positive electrode material.
  17. 17 . The preparation method according to claim 16 , wherein a general formula of the lithium-rich manganese-based material is xLi 2 MnO 3 ·(1−x)LiNi a CO b Mn c O 2 , wherein a+b+c=1, 0≤a≤1, 0<b≤1, 0<c≤1, and 0<x<1; or, the general formula of the lithium-rich manganese-based material is xLi 2-α MnO 3 ·(1−x)Li 1-β Ni a Co b Mn c M d O 2-γ , wherein a+b+c+d=1, d>0, 0<α+β≤0.2, 0<γ≤0.1, and 0<x<1; and M is one or more of Mg, Al, Ti, Cr, Zr, Nb, Mo, Ta, W, La and Ce.
  18. 18 . The preparation method according to claim 10 , wherein a solid-to-liquid ratio of the lithium-rich manganese-based material and the mixed solution is (50-100) g:(0.1-1) L.
  19. 19 . A positive electrode sheet, comprising a positive electrode active layer and a current collector, wherein the positive electrode active layer comprises the positive electrode material according to claim 1 , a sulfide solid electrolyte, a conductive agent and a binder.
  20. 20 . An all-solid-state battery, comprising the positive electrode sheet according to claim 19 .

Description

CROSS-REFERENCE TO RELATED APPLICATIONS The present application is a continuation-in-part of International Application No. PCT/CN2025/081034, filed on Mar. 6, 2025, which claims priority to China patent application No. 202410257081.7, filed with the China National Intellectual Property Administration on Mar. 6, 2024, and entitled “POSITIVE ELECTRODE MATERIAL AND PREPARATION METHOD THEREOF, POSITIVE ELECTRODE SHEET AND ALL-SOLID-STATE BATTERY”. The entire contents of the aforementioned applications are hereby incorporated by reference. TECHNICAL FIELD The present application relates to the field of battery materials, in particular to a positive electrode material and a preparation method thereof, a positive electrode sheet and an all-solid-state battery. BACKGROUND Among solid electrolytes, sulfide solid electrolytes have attracted wide attention because of their high conductivity, high lithium ion mobility, excellent mechanical performance and thermal stability. Lithium-rich manganese-based positive electrode materials are potential positive electrode materials for high-energy-density lithium-ion batteries, and are beneficial to the assembly of high-energy-density all-solid-state batteries. However, the initial coulombic efficiency of lithium-rich manganese-based positive electrode materials is low, which hinders the commercialization of the lithium-rich manganese-based positive electrode materials. In addition, when lithium-rich manganese-based positive electrode materials contact with mainstream sulfide solid electrolytes, space charge layers may be generated, and at the same time, side reactions may occur to form inert interface layers, which hinders the migration of interface ions. Therefore, while solving the problem of low initial coulombic efficiency of the lithium-rich manganese-based positive electrode materials, reducing the interface reaction between lithium-rich manganese-based positive electrode materials and the sulfide solid electrolytes is helpful to promote their industrialization in the field of all-solid-state batteries. SUMMARY The present application provides a positive electrode material, which solves the problem of low initial coulombic efficiency of lithium-rich manganese-based positive electrode materials, at the same time, reduces the possibility of generating a space charge layer and an inert interface layer when the lithium-rich manganese-based positive electrode materials contact with sulfide solid electrolytes, and improves the migration efficiency of interface ions. The present application also provides a preparation method of the above positive electrode material, which may prepare the above positive electrode material and has a simple process. The present application also provides a positive electrode sheet, which, due to including the above positive electrode material, is helpful to improve the initial coulombic efficiency, discharge specific capacity and cycle performance of the battery when it is used in a battery. The present application also provides an all-solid-state battery, which, due to including the above positive electrode sheet, has high initial coulombic efficiency, discharge specific capacity and cycle performance. In a first aspect, the present application provides a positive electrode material, including a lithium-rich manganese-based positive electrode active material and a coating layer covering at least part of a surface of the lithium-rich manganese-based positive electrode active material, where a molecular formula of the lithium-rich manganese-based positive electrode active material is xLi2-αMnO3·(1−x)Li1-βNiaCobMncO2-γ, where a+b+c=1, 0<α+β≤0.2, 0<γ≤0.1, and 0<x<1; or, the molecular formula of the lithium-rich manganese-based positive electrode active material is xLi2-αMnO3·(1−x)Li1-βNiaCobMncMdO2-γ, where a+b+c+d=1, d>0, 0<α+β≤0.2, 0<γ≤0.1, and 0<x<1; and M is one or more of Mg, Al, Ti, Cr, Zr, Nb, Mo, Ta, W, La and Ce; the coating layer meets the following Formula 1 and Formula 2: 0.5×1⁢0-3 ⁢S/cm≤T≤5×1⁢0-3 ⁢S/cmFormula⁢ 1H≤1⁢0-9 ⁢S/cmFormula⁢ 2where Tis an ionic conductivity of the coating layer, and His an electronic conductivity of the coating layer. Further, the coating layer includes a halide solid electrolyte material. Further, a chemical composition of the halide solid electrolyte material is LidMXe, where M is one or more of Ho, Y, Er and Yb, and X is Cl or Br; and 0<d≤10, and 1≤e≤13. Further, a thickness of the coating layer is at nanoscale, and preferably 5 to 80 nm. Further, a mass ratio of the coating layer in the positive electrode material is 0.1% to 0.5%. Further, the coating layer is dense and free of pores, or contains micropores with a pore diameter of not exceeding 5 nm. Further, a specific surface area of the positive electrode material is 0.5 to 1.3 m2/g; and/or, a size of single crystal grains of the positive electrode material is 0.7 to 1.5 μm, and the particle diameter of the positive electrode material is 4 to 6 μm. In