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CN-117430170-B - Positive electrode material precursor, preparation method thereof, positive electrode material, lithium ion battery and electric equipment

CN117430170BCN 117430170 BCN117430170 BCN 117430170BCN-117430170-B

Abstract

The application provides a positive electrode material precursor and a preparation method thereof, a positive electrode material, a lithium ion battery and an electric device, wherein the positive electrode material precursor comprises secondary particles composed of a plurality of primary particles, the secondary particles comprise an inner layer, an intermediate layer and an outer layer from inside to outside, wherein the porosity of the outer layer is greater than the porosity of the inner layer. The secondary particles of the positive electrode material precursor provided by the embodiment of the application have a structure that the inner layer is unordered and loose and porous, the middle layer is dense and has few holes, and the outer layer is loose and porous, and the relatively loose inner layer and the outer layer are connected through the dense middle layer, so that the pressure resistance of the overall structure of the secondary particles is improved, the structural stability is higher, the problems of cracking, powdering and the like of the material can be avoided, and the circulation stability and the safety performance of the positive electrode material are greatly improved.

Inventors

  • JI FANGLI
  • Tuo Huaijin
  • YIN WEI
  • YANG CHANGJUN
  • ZHANG JUN
  • CHEN YIZHONG
  • Xie Zijuan

Assignees

  • 中伟新材料股份有限公司
  • 湖南中伟新能源科技有限公司

Dates

Publication Date
20260512
Application Date
20230922

Claims (15)

  1. 1. The positive electrode material precursor is characterized by comprising secondary particles composed of a plurality of primary particles, wherein the secondary particles comprise an inner layer, an intermediate layer and an outer layer from inside to outside, the porosity of the outer layer is greater than the porosity of the inner layer, the area ratio S1 of the intermediate layer to the inner layer is 1.3-2.5 on the section of the secondary particles, the area ratio S2 of the outer layer to the intermediate layer is 1.0-3.0 on the section of the secondary particles, the secondary particles are spherical or quasi-spherical, and the primary particles forming the outer layer are dendritic.
  2. 2. The positive electrode material precursor according to claim 1, wherein the precursor satisfies at least one of the following conditions a to g: a. The porosity difference between the inner layer and the middle layer is 1% -10%; b. The difference of the porosities of the outer layer and the middle layer is 5% -20%; c. the difference of the porosities of the outer layer and the inner layer is 2% -20%; d. The porosity of the inner layer is 0.05% -10%; e. the porosity of the intermediate layer is 0.01% -5%; f. the porosity of the outer layer is 5.0% -20.0%; g. the positive electrode material precursor further comprises a hollow layer, and the precursor sequentially comprises a hollow layer, an inner layer, an intermediate layer and an outer layer from inside to outside.
  3. 3. The positive electrode material precursor according to claim 2, wherein the precursor satisfies at least one of the following conditions: the difference of the porosities of the inner layer and the middle layer is 2% -5%; The difference of the porosities of the outer layer and the middle layer is 5.5% -15%; the difference of the porosities of the outer layer and the inner layer is 3% -10%; the porosity of the inner layer is 2.0% -4.5%; the porosity of the intermediate layer is 0.05% -1.0%; the porosity of the outer layer is 6% -12%.
  4. 4. The positive electrode material precursor according to any one of claims 1 to 3, wherein the precursor satisfies at least one of the following conditions h to k: h. the radius of the hollow layer is 0.5-1.5 mu m; i. the thickness of the inner layer is 0.8-1.8 mu m; j. The thickness of the intermediate layer is 1.3-2.1 mu m; k. the thickness of the outer layer is 1.2-3.7 μm.
  5. 5. The positive electrode material precursor according to any one of claims 1 to 3, wherein the precursor satisfies at least one of the following conditions (1) to (11): (1) The primary particles constituting the outer layer have an average aspect ratio of 5 to 11; (2) The D50 of the secondary particles is 9.0-14.0 mu m; (3) The particle size distribution span value of the secondary particles is 0.5-1.0; (4) The particle breakage of the secondary particles is 10.0% -21.5%; (5) The specific surface area of the secondary particles is 7.5-16.5m 2 /g; (6) The tap density of the secondary particles is 1.7-2.3g/cm 3 ; (7) The half-peak width alpha of the characteristic peak of the (001) crystal face of the precursor is 0.2-0.6 degrees; (8) The half-peak width beta of the characteristic peak of the (101) crystal face of the precursor is 0.2-0.6 degrees; (9) The ratio beta/alpha of the half-peak width beta of the characteristic peak of the (101) crystal face to the half-peak width alpha of the characteristic peak of the (001) crystal face of the precursor is 1.0-1.3; (10) The peak intensity ratio I 001 /I 101 of the characteristic peak of the (001) crystal face of the precursor to the characteristic peak of the (101) crystal face of the precursor is 1.4-1.7; (11) The chemical general formula of the precursor is Ni x Co y M 1-x-y (OH) 2 , wherein x is more than or equal to 0.8 and less than or equal to 1, y is more than or equal to 0.2, and M is at least one of Mn, al, zr, ti, cr, mo, W, B, ba, nb and Sr.
  6. 6. The positive electrode material precursor according to claim 5, wherein the precursor satisfies at least one of the following conditions: The half-peak width alpha of the characteristic peak of the (001) crystal face of the precursor is 0.30-0.55 degrees; The half-peak width beta of the characteristic peak of the (101) crystal face of the precursor is 0.30-0.58 degrees; the ratio beta/alpha of the half-peak width beta of the characteristic peak of the (101) crystal face to the half-peak width alpha of the characteristic peak of the (001) crystal face of the precursor is 1.1-1.22.
  7. 7. The positive electrode material precursor according to claim 6, wherein, The half-width alpha of the characteristic peak of the (001) crystal face of the precursor is 0.40-0.47 degrees, and/or, The half-peak width beta of the characteristic peak of the (101) crystal face of the precursor is 0.52-0.56 degrees.
  8. 8. A method for producing the positive electrode material precursor according to any one of claims 1 to 7, comprising the steps of: Mixing a metal salt solution with a precipitator and a complexing agent for a first reaction to obtain seed crystals; Mixing the seed crystal with a metal salt solution, a precipitator and a complexing agent for a second reaction to obtain a reaction product; Post-processing the reaction product to obtain a positive electrode material precursor; The reaction temperature of the first reaction is 55-85 ℃, the reaction temperature of the second reaction is 55-85 ℃, the end reaction temperature of the second reaction is higher than the initial reaction temperature, and the pH value of a reaction system of the first reaction and the second reaction is 10.50-12.10.
  9. 9. The method for preparing a positive electrode material precursor according to claim 8, The preparation method satisfies at least one of the following conditions (1) - (4): (1) The metal salts include soluble salts of nickel, cobalt and/or manganese; (2) The total concentration of metal ions of the metal salt solution is 1-5mol/L; (3) The precipitant comprises at least one of sodium hydroxide, potassium hydroxide and lithium hydroxide; (4) The complexing agent comprises at least one of ammonia water, ammonium bicarbonate solution, ammonium carbonate solution, EDTA, ethylenediamine, sodium citrate and urea.
  10. 10. The method for producing a positive electrode material precursor according to claim 9, wherein the production method satisfies at least one of the following conditions: The soluble salt comprises at least one of sulfate, nitrate, acetate and chloride; the concentration of the precipitant is 2-20mol/L; the complexing agent is ammonia water with the mass fraction of 15-35%.
  11. 11. The method for producing a positive electrode material precursor according to any one of claims 8 to 10, wherein, The preparation method meets at least one of the following ①-⑤ conditions: ① The reaction temperature of the second reaction is higher than the reaction temperature of the first reaction; ② The complexing agent comprises ammonia water, and the ammonia concentration of the first reaction and the second reaction is 5.0-12.6g/L; ③ In the first reaction and the second reaction, the feeding flow rate of the metal salt solution is 100L/h-700L/h; ④ In the second reaction process, the feeding flow rate of the metal salt solution is gradually increased along with the time; ⑤ The first reaction and the second reaction are both carried out in a stirring state, and the stirring rotating speed is 100-240r/min.
  12. 12. The method for producing a positive electrode material precursor according to any one of claims 8 to 10, wherein the end reaction temperature of the second reaction is 10 to 20 ℃ higher than the initial reaction temperature.
  13. 13. A positive electrode material, characterized by being prepared from the positive electrode material precursor according to any one of claims 1 to 7.
  14. 14. A lithium ion battery prepared from the positive electrode material of claim 13.
  15. 15. An electrical device comprising the lithium-ion battery of claim 14.

Description

Positive electrode material precursor, preparation method thereof, positive electrode material, lithium ion battery and electric equipment Technical Field The application relates to the technical field of positive electrode materials, in particular to a positive electrode material precursor, a preparation method thereof, a positive electrode material, a lithium ion battery and electric equipment. Background The lithium ion battery is one of the representatives of clean energy sources, has the advantages of high energy density, good safety, long cycle life, environmental friendliness, low cost and the like, and is widely applied to various fields such as energy storage power systems of waterpower, firepower, solar energy and the like, portable electronic equipment, electric automobiles, military equipment, aerospace and the like. The four main materials of the lithium ion battery comprise a positive electrode, a negative electrode, a diaphragm and electrolyte, wherein the positive electrode is a core for determining indexes such as capacity, multiplying power, service life and safety. Currently, positive electrode materials that have been developed and applied mainly include Lithium Cobalt Oxide (LCO), lithium iron phosphate (LFP), lithium Manganate (LMO), ternary materials of lithium Nickel Cobalt Manganate (NCM), lithium nickel cobalt aluminate (NC a), and the like. The ternary positive electrode material is used as a latter part, and has the advantages of higher specific capacity, higher cycle performance, lower preparation cost and the like compared with LCO and LFP. The ternary positive electrode material can almost completely bear the internal structural characteristics of the precursor, at present, along with the development of high nickel of the ternary positive electrode material precursor, the specific capacity of the material is obviously improved, but the structural stability of the material is insufficient, the problems of material cracking, pulverization and the like are easy to occur, and the circulation and the safety of a battery are influenced. Disclosure of Invention The application aims to at least improve one of the technical problems in the prior art, and therefore, the application provides a positive electrode material precursor, a preparation method thereof, a positive electrode material, a lithium ion battery and an electric device. The embodiment of the application provides a positive electrode material precursor, which comprises secondary particles composed of a plurality of primary particles, wherein the secondary particles comprise an inner layer, an intermediate layer and an outer layer from inside to outside, and the porosity of the outer layer is greater than the porosity of the inner layer. The positive electrode material precursor provided by the embodiment of the application has an inner layer, an intermediate layer and an outer layer from inside to outside through special control of different reaction conditions of three stages, and is in a core-shell structure. The core-shell structure has obvious adjustable physical and chemical characteristics, so that the crystal lattice can be enhanced to a certain extent, the interface reaction is controlled, the contact area between the positive electrode material and the electrolyte is regulated, and the specific capacity, the safety, the cycle performance and the like of the material are improved. Specifically, the porosity of the inner layer is larger than that of the middle layer and smaller than that of the outer layer in the embodiment of the application, namely, the secondary particles are of a structure with unordered loose and porous inner layer, dense and less-porous middle layer and loose and porous outer layer, the relatively loose inner layer and the outer layer are connected through the dense middle layer, so that the pressure resistance of the whole structure of the secondary particles is improved, the structural stability is higher, the problems of cracking, powdering and the like of the materials can be avoided, and the cycling stability and the safety performance of the positive electrode material are greatly improved. In addition, the loose inner layer can provide a buffer space for stress generated by the expansion of the inside of the particles, so that the rapid deintercalation and the damage of a crystal structure of lithium ions can be avoided when the porous inner layer is used for preparing a lithium ion battery, and the diffusion resistance of the lithium ions can be reduced, thereby providing an effective lithium ion diffusion channel, and improving the performances such as the circulation stability performance, the capacity exertion and the like of the material. In some embodiments of the application, the precursor satisfies at least one of the following conditions a-g: a. the porosity difference between the inner layer and the middle layer is 1% -10%, optionally 2% -5%; b. the difference of the porositi