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CN-121983533-A - Sodium iron pyrophosphate coated ternary positive electrode material, preparation method thereof and lithium ion battery

CN121983533ACN 121983533 ACN121983533 ACN 121983533ACN-121983533-A

Abstract

The invention relates to the technical field of battery electrodes, and discloses a sodium iron pyrophosphate coated ternary positive electrode material, a preparation method thereof and a lithium ion battery. The preparation method of the sodium iron pyrophosphate coated ternary positive electrode material comprises the following steps of S1, obtaining a ternary positive electrode material, S2, mixing the ternary positive electrode material, a ferric pyrophosphate precursor and a sodium source to obtain a mixed material, and sintering the mixed material to obtain the sodium iron pyrophosphate coated ternary positive electrode material. According to the preparation method of the sodium iron pyrophosphate coated ternary cathode material, provided by the invention, the one-step collaborative modification of bulk phase doping and surface coating is realized, and meanwhile, the bulk phase structure and interface stability are improved, so that the electrochemical performance of the material is improved. The method has the advantages of strong binding force of the coating layer, simple process, few operation steps, cooperative realization of doping and in-situ coating, and easy industrialized amplification.

Inventors

  • XU KAIHUA
  • WANG YONGKANG
  • ZHOU XIAOYAN
  • ZHANG ZHILI
  • MA YONGSONG
  • CHEN YUJUN

Assignees

  • 格林美（无锡）能源材料有限公司

Dates

Publication Date
20260505
Application Date
20251212

Claims (10)

  1. 1. The preparation method of the sodium iron pyrophosphate coated ternary positive electrode material is characterized by comprising the following steps of: s1, obtaining a ternary positive electrode material; S2, mixing the ternary positive electrode material, the ferric pyrophosphate precursor and a sodium source to obtain a mixed material, and sintering the mixed material to obtain the ferric pyrophosphate sodium coated ternary positive electrode material.
  2. 2. The method for preparing a sodium ferric pyrophosphate coated ternary cathode material according to claim 1, wherein S2 satisfies at least one of the following conditions: (1) The molar ratio of the phosphorus element in the ferric pyrophosphate precursor to the sodium element in the sodium source is (0.6-1.1): 1; (2) The mass ratio of the ternary positive electrode material to the ferric pyrophosphate precursor is (20-200): 1; (3) The sintering atmosphere is air or oxygen; (4) The sintering temperature is 500-700 ℃ and the sintering time is 6-15h; (5) The temperature rising rate of the sintering is 1-5 ℃ per minute; (6) The flow rate of the sintering atmosphere is 1-2L/min; (7) The coating amount of sodium iron pyrophosphate in the sodium iron pyrophosphate coated ternary anode material is 1-3wt%.
  3. 3. The method for preparing a sodium ferric pyrophosphate coated ternary cathode material according to claim 1, wherein at least one of the following conditions is satisfied: (1) The ferric pyrophosphate precursor has a chemical formula of H y Fe 3-x M x (PO 4 ) 4 , wherein M comprises one or more of Ni, mg, ca, ti, zr, cu, and 0< x is less than or equal to 1.2, and 0< y is less than or equal to 4; Preferably, the ferric pyrophosphate precursor has a chemical formula of H 4 Fe 2.5 Cu 0.5 (PO 4 ) 4 ; (2) The sodium source comprises one or more of sodium carbonate, sodium hydroxide and sodium bicarbonate; (3) The specific surface area of the ferric pyrophosphate precursor is 1-10 m 2 /g; (4) The median particle diameter D50 of the ferric pyrophosphate precursor is 5-10 mu m; (5) The chemical formula of the ternary positive electrode material is Li 1+c Ni a Co b Mn 1-a-b O 2 , wherein, the a is more than or equal to 0.8 and less than or equal to 1,0< b more than or equal to 0.1, and more than or equal to 0.5; Preferably, the chemical formula of the ternary positive electrode material is Li 1.05 Ni 0.8 Co 0.1 Mn 0.1 O 2 ; Preferably, the value range of c in the chemical formula of the ternary positive electrode material is 0<c-0.05.
  4. 4. The method for preparing the sodium ferric pyrophosphate coated ternary cathode material according to claim 1, wherein the step S1 comprises the following steps: s1-1, mixing a nickel cobalt manganese hydroxide precursor with a lithium source to obtain a mixture; s1-2, sintering the mixture in the step S1-1, cooling and crushing to obtain a ternary positive electrode material-sintered material; s1-3, washing the ternary positive electrode material by using a calcined material, and then carrying out solid-liquid separation and drying to obtain the ternary positive electrode material.
  5. 5. The preparation method of the sodium ferric pyrophosphate coated ternary cathode material, according to claim 4, wherein the chemical formula of the nickel cobalt manganese hydroxide precursor in S1-1 is Ni x Co y Mn 1-x-y (OH) 2 , x is more than or equal to 0.8 and less than or equal to 1, and y is more than or equal to 0 and less than or equal to 0.1; Preferably, the chemical formula of the nickel cobalt manganese hydroxide precursor in the S1-1 is Ni 0.8 Co 0.1 Mn 0.1 (OH) 2 ; Optionally, the specific surface area of the nickel cobalt manganese hydroxide precursor ranges from 5m 2 /g to 20m 2 /g, and the tap density ranges from 1.0 to 4.0 g/cm 3 ; And/or the median particle diameter D50 of the nickel cobalt manganese hydroxide precursor is in the range of 12-18 μm.
  6. 6. The preparation method of the sodium ferric pyrophosphate coated ternary cathode material according to claim 4 or 5, wherein the molar ratio of the lithium element in the lithium source in S1-1 to the sum of the nickel, cobalt and manganese metal elements in the nickel cobalt manganese hydroxide precursor is (0.8-1.1): 1; And/or the lithium source comprises one or more of lithium carbonate, lithium hydroxide.
  7. 7. The method for preparing the sodium ferric pyrophosphate coated ternary cathode material according to claim 4, wherein the atmosphere sintered in the step S1-2 is air or oxygen; and/or the temperature rising rate of sintering in the step S1-2 is 2-8 ℃ per minute, the sintering temperature is 400-700 ℃, and the sintering time is 14-19h; Optionally, the step of sintering in S1-2 comprises heating the mixture in S1-1 to 300-500 ℃ at a heating rate of 2-4 ℃ per minute and preserving heat for 1-3 hours, and then heating to 500-700 ℃ at a heating rate of 1-3 ℃ per minute and preserving heat for 10-12 hours; preferably, the sintering step in S1-2 comprises heating the mixture in S1-1 to 400 ℃ at a heating rate of 3 ℃ per minute and preserving heat for 2 hours, and then heating to 700 ℃ at a heating rate of 2 ℃ per minute and preserving heat for 12 hours.
  8. 8. The method for preparing a sodium ferric pyrophosphate coated ternary positive electrode material according to claim 4, wherein the washing rotational speed in S1-3 is 200-400 rpm; and/or the solid-liquid separation mode comprises suction filtration or pressure filtration; And/or the temperature of the drying is 80-190 ℃ and the drying time is 2-12 h.
  9. 9. A sodium iron pyrophosphate coated ternary cathode material prepared by the preparation method of any one of claims 1-8.
  10. 10. A lithium ion battery comprising the sodium iron pyrophosphate coated ternary cathode material of claim 9.

Description

Sodium iron pyrophosphate coated ternary positive electrode material, preparation method thereof and lithium ion battery Technical Field The invention relates to the technical field of battery electrodes, in particular to a sodium iron pyrophosphate coated ternary positive electrode material, a preparation method thereof and a lithium ion battery. Background With the popularization of new energy vehicles, the scale of power batteries is continuously expanded, and the demand of positive electrode materials with high energy density is continuously increased. The layered high nickel positive electrode represented by LiNi 0.80Co0.10Mn0.10O2 has been the most prominent, and has been receiving extensive attention from researchers. The high-nickel ternary material has poor air stability, and is easy to react with water and carbon dioxide in the air to form lithium hydroxide and lithium carbonate residual alkali on the surface. In the preparation process of the electrode material, residual alkali can react with PVDF to cause the slurry to be jelly, so that the processing performance of the material is reduced, and the electrochemical performance of the material is also reduced. The enhancement of the air stability of the high-nickel ternary material is a key point of large-scale application of the high-nickel ternary material in power batteries. At present, the high-nickel ternary material is mostly coated with substances such as metal oxide, metal phosphate and the like on the surface so as to improve the air stability and the electrochemical performance, and the traditional coating method adopts a deposition method and a wet chemical method, so that the cost is too high and the large-scale production is difficult. The existing high-nickel ternary material secondary sintering mainly adopts a deposition method and a wet chemical method, and has the defects of excessively high cost and difficult mass production. Compared with a wet method and a deposition method, the dry chemical method has the advantages of simple process, short flow, low cost, no solvent, less equipment investment, no wastewater discharge, more environmental protection, no contact between a matrix material and water, protection of a layered structure of a positive electrode material, no physical and mechanical force mixing of the positive electrode material and a micron or nanometer coating material, easy control of the thickness of the coating layer, and simultaneous addition of a doping agent and a coating agent in the dry mixing process, thereby realizing bulk doping and coating synergistic modification. The dry coating is a solvent-free coating process, wherein a coating substance is mechanically mixed with a positive electrode material, and a coating agent is solidified or reacts with the surface of a substrate by lower-temperature treatment to form a coating layer. However, in the current dry coating, mostly, ex-situ coating is adopted, the coating material is synthesized first, and then the coating material is mixed with the high-nickel ternary material and then subjected to secondary sintering, so that the cycle performance is poor. Disclosure of Invention The invention provides a sodium iron pyrophosphate coated ternary positive electrode material, a preparation method thereof and a lithium ion battery, and achieves the effect of improving the cycle performance of the lithium ion battery. In a first aspect, the invention provides a preparation method of a sodium iron pyrophosphate coated ternary cathode material, which comprises the following steps: s1, obtaining a ternary positive electrode material; S2, mixing the ternary positive electrode material, the ferric pyrophosphate precursor and a sodium source to obtain a mixed material, and sintering the mixed material to obtain the ferric pyrophosphate sodium coated ternary positive electrode material. In an alternative embodiment, S2 satisfies at least one of the following conditions: (1) The molar ratio of the phosphorus element in the ferric pyrophosphate precursor to the sodium element in the sodium source is (0.6-1.1): 1; (2) The mass ratio of the ternary positive electrode material to the ferric pyrophosphate precursor is (20-200): 1; (3) The sintering atmosphere is air or oxygen; (4) The sintering temperature is 500-700 ℃ and the sintering time is 6-15h; (5) The temperature rising rate of the sintering is 1-5 ℃ per minute; (6) The flow rate of the sintering atmosphere is 1-2L/min; (7) The coating amount of sodium iron pyrophosphate in the sodium iron pyrophosphate coated ternary anode material is 1-3wt%. In an alternative embodiment, the preparation method of the sodium ferric pyrophosphate coated ternary cathode material meets at least one of the following conditions: (1) The ferric pyrophosphate precursor has a chemical formula of H yFe3-xMx(PO4)4, wherein M comprises one or more of Ni, mg, ca, ti, zr, cu, and 0< x is less than or equal to 1.2, and 0< y is less than or equal to 4;