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CN-116835670-B - Sodium ion positive electrode material and preparation method thereof

CN116835670BCN 116835670 BCN116835670 BCN 116835670BCN-116835670-B

Abstract

The invention provides a preparation method of a sodium ion positive electrode material, which comprises the steps of annealing and cooling a calcined material in the atmosphere of active gas and carrier gas, wherein the annealing and cooling time is 0.5-5 h, preferably 2-4 h, the active gas is one or more of ammonia, carbon dioxide and formaldehyde, the carrier gas is inert gas, preferably one or more of helium, nitrogen and argon, and the volume content of the active gas is 1-30%, preferably 1% -20% based on the total gas volume of the active gas and the carrier gas. The invention also provides the positive electrode material prepared by the method and application of the positive electrode material. The invention can accelerate the annealing process, reduce the moisture of the material and further reduce the generation of residual alkali.

Inventors

  • LI SHUNLI
  • LU LIN
  • LI QINGLING
  • JIANG ZHIYI

Assignees

  • 江苏天合储能有限公司

Dates

Publication Date
20260505
Application Date
20230719

Claims (20)

  1. 1. A method for preparing a sodium ion positive electrode material, which is characterized by comprising the following steps: (1) Uniformly mixing the precursor, sodium salt and the doping agent, and sintering to obtain a sintered material; (2) Annealing and cooling the first sintering material to room temperature under the atmosphere of active gas and carrier gas; (3) Crushing the first sintered material obtained in the step (2), uniformly mixing the crushed first sintered material with a coating material, and performing sintering treatment for the second time to obtain the sodium ion anode material; Wherein, the The precursor is Ni x Fe y Mn 1-x-y OH 2 , wherein x is 0.2-0.4, y is 0.2-0.4, and x+y is 0.4-0.8; the annealing and cooling time is 0.5-5 h; the active gas is selected from one or more of ammonia and formaldehyde; The carrier gas is an inert gas; the volume content of the active gas is 1-30% based on the total gas volume of the active gas and the carrier gas.
  2. 2. The method of claim 1, wherein, The sodium salt is selected from one or more of sodium carbonate, sodium hydroxide, sodium oxalate and sodium citrate; the dopant is selected from one or more of Li, mg, cu, zn, co, ca, ba, sr, al, B, cr, zr, ti, sn, V, mo, ru, sb or Nb compounds; the mol ratio of the precursor, the sodium salt and the doping agent is (0.9-1.2): 1 (0.001-0.05); The coating material is selected from one or more of boric acid, aluminum oxide and titanium dioxide; the mass of the coating material is 500-1500 ppm of the mass of the sintering material based on the total mass of the sintering material.
  3. 3. The method of claim 1, wherein the annealing temperature reduction time is 2-4 hours.
  4. 4. The method of claim 1, wherein the carrier gas is selected from one or more of helium, nitrogen, and argon.
  5. 5. The method of claim 1, wherein the active gas is present in an amount of 1% to 20% by volume based on the total gas volume of the active gas and the carrier gas.
  6. 6. The method of claim 1, wherein the step of maintaining the temperature after obtaining a frit.
  7. 7. The method of claim 2, wherein in the step (1), the temperature rise rate of the sintering treatment is 2-10 ℃ per minute.
  8. 8. The method of claim 2, wherein in the step (1), the sintering treatment is performed at a temperature of 500 to 1500 ℃.
  9. 9. The method of claim 2, wherein in the step (1), the heat preservation time of the sintering treatment is 8-24 hours.
  10. 10. The method of claim 7, wherein in the step (1), the temperature rise rate of the sintering treatment is 5-10 ℃ per minute.
  11. 11. The method of claim 8, wherein in the step (1), the sintering treatment is performed at a temperature of 700 to 1400 ℃.
  12. 12. The method of claim 9, wherein in the step (1), the heat preservation time of the sintering treatment is 10 to 20 hours.
  13. 13. The method of claim 2, wherein the second sintering process is at a temperature of 100-300 ℃.
  14. 14. The method of claim 13, wherein the second sintering process is performed at a temperature of 150-300 ℃.
  15. 15. A positive electrode sheet, characterized in that a positive electrode material layer of the positive electrode sheet comprises a positive electrode material, a conductive agent and a binder, the positive electrode material being prepared by the method of any one of claims 1 to 14.
  16. 16. The positive electrode sheet according to claim 15, wherein, The conductive agent is selected from one or more of conductive carbon black, carbon fiber, conductive graphite, graphene, carbon nanotube and carbon microsphere, and/or The binder is selected from one or more of PVDF, polytetrafluoroethylene, polyvinyl alcohol, polyolefin, styrene-butadiene rubber, fluorinated rubber, polyurethane and sodium alginate.
  17. 17. The positive electrode sheet of claim 16, wherein the conductive agent is acetylene black.
  18. 18. The positive electrode sheet according to claim 16, wherein the mass fraction of the positive electrode material is 90 to 98wt% based on the total mass of the positive electrode material layer.
  19. 19. The positive electrode sheet according to claim 16, wherein the mass fraction of the conductive agent is 0.5 to 5wt% based on the total mass of the positive electrode material layer.
  20. 20. The positive electrode sheet according to claim 16, wherein the mass fraction of the binder is 0.5 to 5wt% based on the total mass of the positive electrode material layer.

Description

Sodium ion positive electrode material and preparation method thereof Technical Field The invention belongs to the technical field of new energy source sodium ion battery anode materials, and particularly relates to a sodium ion anode material and a preparation method thereof. Background With the rapid development of new energy industry, lithium ion batteries have extremely important roles in energy storage and power batteries thereof, however, since lithium resources are limited and only a small part of lithium salts are stored in China, the price of the lithium ion batteries is rapidly increased. The sodium ion battery has the advantages that the sodium resource is extremely abundant, the manufacturing cost is low, the manufacturing process is compatible with the existing production line, therefore, the sodium ion battery positive electrode material has the function of partial replacement, the sodium ion battery positive electrode material mainly comprises layered oxide, polyanion compounds and Prussian blue analogues, wherein the layered oxide material has relatively high energy density, the manufacturing process is similar to the process of the existing ternary material, and the sodium ion battery positive electrode material has excellent development prospect The surface residual alkali of the sodium ion layered cathode material is higher because the material reacts with oxygen, carbon dioxide, water and the like in the air when contacting the air to produce stable sodium carbonate and sodium hydroxide, so that the performance of the battery cell can be greatly influenced (1) the generated sodium carbonate and sodium hydroxide can block the movement of sodium ions and further increase the impedance of the battery cell, (2) the generated residual alkali is excessive and can possibly generate a gel phenomenon in a slurry mixing stage, (3) the generated sodium carbonate and sodium hydroxide can inevitably consume a part of sodium in a material body, further the valence state of metal elements on the surface of the material is changed, the partial gram capacity is reduced, and (4) the sodium carbonate content is more and can be increased in the circulation and storage processes of the battery cell. In the existing method, CN114171737A adopts a water washing method to reduce the residual alkali content on the surface of the material, and the method is more complex in material preparation process, has lower yield and can have a certain influence on the internal crystal structure of the material. CN111370664a discloses a method of reacting volatile acidic gas with sodium ion positive electrode material in an atmosphere rotary furnace, but strong acidic gas is very likely to cause excessive reaction, and has a great influence on the performance of the material, weak acidic gas is likely to react under high pressure conditions, and the high pressure atmosphere of the rotary furnace is difficult to achieve. It is therefore desirable to find a method of preparation that reduces the residual alkali content of the positive electrode material and results in a layered material that is stable in air. Disclosure of Invention The invention aims to adopt high-temperature annealing and simultaneously introduce active gas and carrier gas to accelerate the annealing process and reduce the moisture of the material, reduce the reaction of the material with air to produce residual alkali in the cooling stage, and simultaneously reduce the loss of sodium content in a bulk phase. The first aspect of the invention provides a preparation method of a sodium ion positive electrode material, which comprises the steps of annealing and cooling a calcined material in the atmosphere of active gas and carrier gas, wherein the annealing and cooling time is 0.5-5 h, preferably 2-4 h, the active gas is one or more of ammonia, carbon dioxide and formaldehyde, the carrier gas is inert gas, preferably one or more of helium, nitrogen and argon, and the volume content of the active gas is 1-30%, preferably 1-20% based on the total gas volume of the active gas and the carrier gas. In one or more embodiments, the method comprises the steps of: (1) Uniformly mixing the precursor, sodium salt and the doping agent, and sintering to obtain a sintered material; (2) Annealing and cooling the first sintering material to room temperature under the atmosphere of the active gas and the carrier gas; (3) Crushing the first sintering material obtained in the step (2), uniformly mixing the crushed first sintering material with a coating material, carrying out sintering treatment for the second time to obtain the sodium ion anode material, Wherein, the The precursor is Ni xFeyMn1-x-yOH2, wherein x is 0.2-0.4, y is 0.2-0.4, and x+y is 0.4-0.8; The sodium salt is selected from one or more of sodium carbonate, sodium hydroxide, sodium oxalate and sodium citrate; The dopant is selected from one or more of Li, ni, mg, cu, mn, zn, co, ca, ba, sr, al, B, cr, zr, ti, sn,