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US-20260125282-A1 - POSITIVE ELECTRODE MATERIAL AND PREPARATION METHOD AND USE THEREOF

US20260125282A1US 20260125282 A1US20260125282 A1US 20260125282A1US-20260125282-A1

Abstract

Provided are a positive electrode material, and a preparation method and a use thereof. The positive electrode material has a Dv50 value of α, with the unit of um, the lithium-rich amount of the positive electrode material is y, and the average porosity of the positive electrode material is denoted as β % in percentage, α, β, and γ satisfying: δ=β−[2α+75γ]/3, where 0≤δ≤4.0. By means of defining the relational expression of the Dv50, the average porosity and the lithium-rich amount of the positive electrode material, a lithium-ion battery prepared by the positive electrode material has excellent specific capacity, energy density, rate capability and cycle performance simultaneously, and particularly can maintain excellent electrochemical properties at high voltage.

Inventors

  • Liangchen DONG
  • Sangyul YOU
  • Wenxu Zhang
  • LEILEI LIU
  • Xiahui Ren
  • YICHONG CHEN
  • Yu Chen
  • Daoyan FENG
  • Rui Liu
  • Jonghee Lee

Assignees

  • NINGBO RONBAY NEW ENERGY TECHNOLOGY CO., LTD.

Dates

Publication Date
20260507
Application Date
20251230
Priority Date
20230913

Claims (19)

  1. 1 . A positive electrode material, wherein the positive electrode material has a Dv50 value of α, with a unit of μm; a lithium-rich amount of the positive electrode material is γ; an average porosity of the positive electrode material is denoted as β % in percentage, and wherein α, β, and γ satisfy δ=β−[2α+75γ]/3, and 0≤δ≤4.0.
  2. 2 . The positive electrode material according to claim 1 , wherein the positive electrode material comprises a secondary particle.
  3. 3 . The positive electrode material according to claim 2 , wherein a total molar amount of elements distributed in a cationic form in the secondary particle is A, a total molar amount of elements distributed in an anionic form in the secondary particle is B, and A and B satisfy: 0.985 ≤ A / B ≤ 1. .
  4. 4 . The positive electrode material according to claim 3 , wherein the secondary particle comprise a doping metal element distributed in the cationic form, a doping non-metal element distributed in the anionic form; wherein a molar ratio of the doping metal element to other element distributed in the cationic form in the secondary particle except for a lithium ion is not higher than 5%; and/or, a molar ratio of the doping non-metal element to the sum of elements distributed in the anionic form in the secondary particle is not higher than 10%.
  5. 5 . The positive electrode material according to claim 2 , wherein a chemical formula of the secondary particle is Li 1+x-2y M z M′ 1-x-z O 2-y-t R t , wherein M is Ni a Co b Mn c , a+b+c=1.0, 0≤b≤0.10, a≥2b, 1.5≤c/(a+b)≤3.0, x=(c−a)/(2+c−a), 0.985≤(2−2y)/(2−y)≤1.0, (19−19x)/20≤z≤(1−x), 0≤t≤(2−y)/10; and wherein M′ is at least one of the doping metal element and P; and R is the doping non-metal element.
  6. 6 . The positive electrode material according to claim 5 , wherein the M′ comprises at least one of Cr, Mo, W, Ta, Nb, P, Sb, Te, Hf, Ce, Ti, Zr, Sn, La, Al, Mg, Fe, K, and Na; and/or, R comprises at least one of F and S.
  7. 7 . The positive electrode material according to claim 2 , wherein the positive electrode material has a Dv50 of 2.5-10.6 μm; and/or, a minimum particle diameter Dv min of the positive electrode material is not less than 0.6 μm; and/or, the secondary particle is formed by agglomeration of primary particles, and an average thickness of the primary particles is 80-250 nm; and/or, a specific surface area of the secondary particle is not less than 0.5 m 2 /g and not more than 1.5 m 2 /g; and/or, β is 7-13; and/or, the lithium-rich amount γ is 0.09-0.21.
  8. 8 . The positive electrode material according to claim 1 , wherein the positive electrode material further comprises a coating layer covering at least a part of a surface of the secondary particle.
  9. 9 . The positive electrode material according to claim 8 , wherein a ratio of a molar amount of a coating layer material to a total molar amount of the positive electrode material is (0.2-1.0):100; and/or, a coating layer material is phosphate and/or inert oxide, the phosphate comprises at least one of AlPO 4 and LaPO 4 , and the inert oxide comprises at least one of Al 2 O 3 , TiO 2 , ZrO 2 , and La 2 O 3 .
  10. 10 . A preparation method for the positive electrode material according to claim 1 , comprising the following steps: mixing a metal salt solution, an alkali solution, and an oxidant to obtain a reaction system, making the reaction system undergo precipitation reaction to obtain a precursor; wherein the oxidant comprises sodium hypochlorite, and a concentration of the oxidant in the reaction system is 0.2-2 g/L; mixing a precursor, a lithium salt, and a pore-forming agent to obtain a first mixture, and subjecting the first mixture to a first sintering treatment to obtain the positive electrode material.
  11. 11 . The preparation method according to claim 10 , wherein the first mixture further comprises a compound containing a doping element; and/or, after the first sintering treatment, the method further comprises: mixing a first sintering treatment product with a coating layer material to obtain a second mixture, and subjecting the second mixture to a second sintering treatment to obtain the positive electrode material.
  12. 12 . The preparation method according to claim 11 , wherein the precipitation reaction has a condition of: a stirring speed of 700-800 rpm, a temperature of 50-70° C., and pH 9.5-11.5; the first sintering treatment has a temperature of 800-950° C. and a holding time of 10-15 h; and/or, the coating layer material comprises inert oxide, and the second sintering treatment has a temperature of 500-800° C., a heating rate of 5-10° C./min and a holding time 5-10 h; and/or, the coating layer material comprises phosphate, and the second sintering treatment has a temperature of 700-900° C., a heating rate of 5-10° C./min, and a holding time is 5-10 h.
  13. 13 . The preparation method according to claim 10 , wherein a mass of the pore-forming agent is 0.1 wt % to 1.0 wt % of a mass of the precursor; the pore-forming agent comprises at least one of ammonium carbonate, ammonium sulfate, ammonium persulfate, ammonium nitrate, and ammonium chloride.
  14. 14 . A positive electrode sheet comprising the positive electrode material according to claim 1 .
  15. 15 . The positive electrode sheet according to claim 14 , wherein the positive electrode sheet comprises a current collector, and a positive electrode active material layer located on at least one functional surface of the current collector; the positive electrode active material layer comprises the positive electrode material, a conductive agent, and a binder, wherein a ratio of a mass of the positive electrode material to a total mass of the positive electrode active material layer is not less than 94 wt %.
  16. 16 . A lithium-ion battery comprising the positive electrode sheet according to claim 14 .
  17. 17 . The lithium-ion battery according to claim 16 , wherein the lithium-ion battery further comprises a separator, a negative electrode sheet, and an electrolyte; the negative electrode sheet is selected from at least one of a lithium sheet, graphite, and a silicon-carbon negative electrode.
  18. 18 . The lithium-ion battery according to claim 16 , wherein an increase rate of average porosity of the positive electrode material on the positive electrode sheet is less than 2% after the lithium-ion battery is cycled under charge and discharge conditions of 2.5-4.5 V and 0.5 C/1.0C for 200 cycles.
  19. 19 . An electrical device comprising the lithium-ion battery according to claim 16 , the electrical device comprises an electric vehicle, a manned electric aircraft, or an unmanned aerial vehicle.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of International Application No. PCT/CN2024/118752, filed on Sep. 13, 2024, which claims priority to a Chinese patent application number 202311186638.4, filed on Sep. 13, 2023, both of which are hereby incorporated by reference in their entireties. TECHNICAL FIELD The present application relates to a positive electrode material and a preparation method and use thereof, and belongs to the technical field of lithium-ion batteries. BACKGROUND The property of the positive electrode material directly determines the performance of the lithium-ion battery. The specific capacity, cycle performance, and rate capability of the positive electrode material will directly affect the energy density, service life, and fast charging performance of the lithium-ion battery. Lithium-rich positive electrode material (e.g. layered lithium-rich positive electrode material Li[Li1-x-y-zNixCoyMnz]O2) has attracted much attention due to its high specific capacity and cost advantages, but its rate performance is worse than that of ternary positive electrode material. Under the industrialization background of increasingly high fast charging requirements, how to improve the rate performance of the lithium-rich positive electrode material is the research focus in this field. The high specific capacity of the lithium-rich positive electrode material is mainly attributed to the reversible redox process of doped anions and the formation of local electron vacancy on an oxygen atom. In the actual use process, in order to avoid a series of problems caused by extremely high voltage, the application voltage window can be appropriately reduced to provide excellent cycle stability when the capacity is slightly lower, but the rate performance is still at a disadvantage and unable to meet the requirements of high-power density, resulting in limited fast charging performance. That is because anionic redox has a greater impact on the stability of the crystal structure and a slower response than cationic redox. However, compared with the dynamic performance of layered ternary materials, the dynamic performance of layered ternary materials only cationic redox is utilized to provide capacity. Compared with the ternary positive electrode material, lithium-rich positive electrode material has problems such as high unit-cell volume change rate, serious lattice distortion, and limited dynamic performance, which in turn leads to difficulty in lithium-ion migration, increased polarization, voltage hysteresis and so on, making reduced charge and discharge energy efficiency of the positive electrode material and not able to achieve higher rate performance. At this stage, the structure, particle size and particle size distribution of secondary particles are mostly adjusted, with the intention of increasing the rate performance of lithium-rich positive electrode materials by improving the dispersibility of lithium-rich positive electrode materials in the positive electrode slurry and shortening the lithium-ion transmission distance. For example, in patent documents CN106340638A, U.S. Pat. No. 9,478,808B2, U.S. Pat. No. 10,978,709B2, and the like, the mentioned methods provide some directions for improving rate performance, but the rate performance of lithium-rich positive electrode materials needs to be further improved. SUMMARY In a positive electrode material provided in the present application, by defining the relationship expression among Dv50, average porosity and lithium-rich amount of the positive electrode material, the lithium-ion battery prepared by the positive electrode material has excellent specific capacity, energy density, rate performance, and cycle performance, especially can maintain excellent electrochemical performance under high voltage. The present application also provides a method for preparing the positive electrode material, and the positive electrode material prepared by the method is applied to a lithium-ion battery, so that the lithium-ion battery has excellent specific capacity, rate performance and cycle performance. The present application also provides a positive electrode sheet including the above described positive electrode material, and thus a lithium-ion battery assembled from the positive electrode sheet has excellent specific capacity, energy density, rate performance, and cycle performance. The present application also provides a lithium-ion battery including the above described positive electrode sheet, and thus the lithium-ion battery assembled from the positive electrode sheet has both excellent specific capacity, rate performance, and cycle performance. According to a first aspect of the present application, there is provided a positive electrode material, the positive electrode material has a Dv50 value of α, with a unit of μm; the positive electrode material has a lithium-rich amount of γ; an average porosity of the positive electrode material