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CN-118164446-B - Lithium iron phosphate battery material, precursor thereof, and preparation method and application thereof

CN118164446BCN 118164446 BCN118164446 BCN 118164446BCN-118164446-B

Abstract

The application relates to the technical field of battery materials, and provides a lithium iron phosphate battery material, a precursor thereof, a preparation method and application thereof. Disclosed are lithium iron phosphate precursors, which are spherical in shape, comprising an iron phosphate shell and a carbon-iron oxide network structure within the iron phosphate shell. The preparation method of the precursor comprises the steps of taking nano hydrogel particles as templates, enabling ferric ions to be adsorbed on the surfaces of the nano hydrogel particles, enabling the ferric ions to react with phosphate radical, and calcining to carbonize the nano hydrogel particles. A lithium iron phosphate battery material is disclosed that includes a lithium iron phosphate housing and a carbon-lithium iron phosphate structure located within the lithium iron phosphate housing. The disclosed preparation method comprises mixing and sintering a precursor and a lithium source. The special microstructure of the lithium iron phosphate battery material provided by the application is beneficial to improving the infiltration area of electrolyte, shortening the transmission path of lithium ions and improving the multiplying power performance of the battery.

Inventors

  • YU HAIJUN
  • LI AIXIA
  • XIE YINGHAO
  • LI CHANGDONG

Assignees

  • 广东邦普循环科技有限公司
  • 湖南邦普循环科技有限公司

Dates

Publication Date
20260505
Application Date
20240313

Claims (20)

  1. 1. The lithium iron phosphate precursor is characterized by being spherical, and comprises an iron phosphate shell and a first network structure positioned in the iron phosphate shell, wherein the first network structure is a carbon network interwoven ferric oxide structure.
  2. 2. The lithium iron phosphate precursor of claim 1, wherein the particle size of the precursor is 300-600 nm.
  3. 3. A method for preparing a lithium iron phosphate precursor, comprising: Taking nano hydrogel particles as templates, and adsorbing ferric ions to the surfaces and the interiors of the nano hydrogel particles in a solution system to obtain a solution containing a first intermediate, wherein at least one of-COOH and amino groups are arranged on the surfaces and the interiors of the nano hydrogel particles; Mixing phosphate ions with the solution containing the first intermediate product, enabling at least a part of phosphate ions to react with ferric ions on the surface of the first intermediate product, and then sequentially carrying out solid-liquid separation and freeze drying to obtain a second intermediate product; Calcining the second intermediate in an oxygen-containing environment to carbonize the nano-hydrogel particles in the second intermediate and oxidize ferric ions entering the nano-hydrogel particles to ferric oxide; The nano hydrogel particles are obtained by reacting acid anhydride acylated chitosan with acid in a solution system for self-assembly, wherein the mode of reacting the acid anhydride acylated chitosan with the acid comprises the following steps: Dropwise adding an acid anhydride acylated chitosan solution into the acid solution, controlling the pH value of a reaction system to be 1.8-2.2 in the whole process, and reacting to obtain a nano hydrogel particle solution; The way of adsorbing ferric ions to the surface and interior of the nano-hydrogel particles to obtain a first intermediate product comprises: Mixing and reacting a solution containing the nano hydrogel particles with ferric salt, and keeping the pH value of a solution system to be 1.8-2.2 in the process, so that a part of ferric ions are adsorbed to the surfaces of the nano hydrogel particles, and a part of ferric ions enter the inside of the nano hydrogel particles; mixing phosphate ions with the solution containing the first intermediate product in a manner that causes at least a portion of the phosphate ions to react with ferric ions on the surface of the first intermediate product comprising: mixing phosphate ions with the solution containing the first intermediate product, controlling the reaction temperature to be 55-65 ℃, and controlling the pH value of a solution system in the reaction process to be 1.8-2.2; And placing the second intermediate product in an environment with oxygen to calcine at 500-700 ℃ for 4-8 hours.
  4. 4. The method according to claim 3, wherein the concentration of the acid anhydride acylated chitosan solution is 0.2 to 0.4 g/L.
  5. 5. The method according to claim 3, wherein the volume ratio of the acidic solution to the acid anhydride acylated chitosan solution is 1:1.8-2.2.
  6. 6. A method of preparing according to claim 3, wherein the acidic solution is a solution of at least one of formic acid, hydrochloric acid, acetic acid and lactic acid.
  7. 7. The process according to claim 3, wherein the acid anhydride acylated chitosan is obtained by reacting chitosan with an acid anhydride compound.
  8. 8. The method according to claim 7, wherein the acid anhydride compound is at least one selected from the group consisting of maleic anhydride and succinic anhydride.
  9. 9. The preparation method according to any one of claims 3 to 8, wherein the solution containing the nano hydrogel particles is mixed with ferric salt for 10 to 14 hours.
  10. 10. The method according to any one of claims 3 to 8, wherein the solution containing the nano-hydrogel particles is mixed with a trivalent iron salt in such a manner that the concentration of the trivalent iron ions in the mixed solution is 0.5 to 1 mol/L.
  11. 11. The preparation method of any one of claims 3 to 8, further comprising continuously adding the ferric salt to the intermediate mixed solution after obtaining the intermediate mixed solution, so that the surface of the nano-hydrogel particles fully adsorbs ferric salt ions.
  12. 12. The preparation method according to claim 11, wherein the ferric salt is supplemented according to the concentration of the ferric ions which can be measured in the solution after the supplementing being 0.5-1 mol/L, and the ferric ions which can be measured are all ferric ions in the solution minus the ferric ions entering the interior of the nano hydrogel particles.
  13. 13. The method according to any one of claims 3 to 8, wherein the ferric salt solution is a solution of at least one of ferric nitrate and ferric chloride.
  14. 14. The method according to any one of claims 3 to 8, wherein phosphate ions are mixed with the solution containing the first intermediate for a reaction time of 5 to 9 hours.
  15. 15. The method according to any one of claims 3 to 8, wherein the solution containing the first intermediate further has free ferric ions, and when at least a part of phosphate reacts with the ferric ions on the surface of the first intermediate, a part of phosphate reacts with the free ferric ions in the solution to form ferric phosphate, and the generated ferric phosphate is deposited on the surface of the nano hydrogel particles.
  16. 16. The method according to any one of claims 3 to 8, wherein the reaction of phosphate ions with ferric ions on the surface of the first intermediate product is performed under stirring at 600 to 900rpm.
  17. 17. The method according to any one of claims 3 to 8, wherein the phosphate group is provided by at least one of ammonium hydrogen phosphate, ammonium dihydrogen phosphate and phosphoric acid.
  18. 18. The method according to any one of claims 3 to 8, wherein the second intermediate product is calcined in an oxygen-containing atmosphere, and the oxygen content by volume in the calcining atmosphere is 5 to 10%.
  19. 19. The lithium iron phosphate battery material is characterized by being spherical, and comprises a lithium iron phosphate shell and a second network structure positioned in the lithium iron phosphate shell, wherein the second network structure is a structure of carbon network interweaved lithium iron phosphate.
  20. 20. The lithium iron phosphate battery material of claim 19, wherein the particle size of the lithium iron phosphate battery material is 300-600 nm.

Description

Lithium iron phosphate battery material, precursor thereof, and preparation method and application thereof Technical Field The application belongs to the technical field of battery materials, and provides a lithium iron phosphate battery material, a precursor thereof, a preparation method and application thereof. Background Since lithium ion batteries are an important energy storage device, they have the advantages of high energy density and long cycle life, and have been widely used in portable electronic products. With the rapid development of electric vehicles and smart grids, the demand for lithium ion batteries with better performance is becoming more and more urgent. The lithium iron phosphate anode material rapidly occupies the current market because of the characteristics of good safety performance, environmental protection, high capacity, high cost performance of raw materials and the like. However, liFePO 4 is also subject to market disputes due to the disadvantages of low ion transport rates, poor conductivity, etc. The morphology characteristics of the precursor and the preparation method have great influence on the performance of the lithium iron phosphate, so that it is very important to find suitable process conditions for preparing the high-quality ferric phosphate precursor. In view of this, the present application has been made. Disclosure of Invention The application aims to provide a lithium iron phosphate battery material, a precursor thereof, a preparation method, a positive electrode and a battery. In a first aspect, the present application provides a lithium iron phosphate precursor, the precursor being spherical and comprising an iron phosphate shell and a first network structure within the iron phosphate shell, the first network structure being a carbon network interlaced iron oxide structure. In an alternative embodiment, the particle size of the precursor is 300 to 600nm. In a second aspect, the present application provides a method for preparing a lithium iron phosphate precursor, comprising: Taking nano hydrogel particles as templates, and adsorbing ferric ions to the surfaces and the interiors of the nano hydrogel particles in a solution system to obtain a solution containing a first intermediate, wherein at least one of-COOH and amino groups are arranged on the surfaces and the interiors of the nano hydrogel particles; mixing phosphate ions with the solution containing the first intermediate product, enabling at least a part of phosphate ions to react with ferric ions on the surface of the first intermediate product, and then sequentially carrying out solid-liquid separation and drying to obtain a second intermediate product; calcining the second intermediate in an oxygen-containing environment to carbonize the nano-hydrogel particles in the second intermediate and oxidize ferric ions entering the nano-hydrogel particles to ferric oxide. In an alternative embodiment, the nano-hydrogel particles are obtained by reacting acid anhydride acylated chitosan with acid in a solution system for self-assembly. In an alternative embodiment, the means for reacting the anhydride acylated chitosan with an acid comprises: and (3) dropwise adding an acid anhydride acylated chitosan solution into the acid solution, controlling the pH of a reaction system to be 1.8-2.2 in the whole process, and reacting to obtain the nano hydrogel particle solution, wherein the concentration of the acid anhydride acylated chitosan solution is 0.2-0.4 g/L. In an alternative embodiment, the volume ratio of the acid solution to the acid anhydride acylated chitosan solution is 1:1.8-2.2. In an alternative embodiment, the acidic solution is a solution of at least one of formic acid, hydrochloric acid, acetic acid, and lactic acid. In an alternative embodiment, the anhydride acylated chitosan is obtained by reacting chitosan with an anhydride compound. In an alternative embodiment, the anhydride-based compound is selected from at least one of maleic anhydride and succinic anhydride; in an alternative embodiment, the drying means is freeze drying. In an alternative embodiment, the means for adsorbing ferric ions to the surface of the hydrogel nanoparticle to provide a first intermediate comprises: And mixing the solution containing the nano hydrogel particles with a ferric salt solution for reaction for 10-14 h, and keeping the pH value of a solution system to be 1.8-2.2 in the process, so that a part of ferric ions are adsorbed to the surfaces of the nano hydrogel particles, and a part of ferric ions enter the inside of the nano hydrogel particles. Optionally, mixing the solution containing the nano hydrogel particles with ferric salt according to the ferric ion concentration of 0.5-1 mol/L in the mixed solution; In an alternative embodiment, mixing a solution containing nano hydrogel particles with a ferric salt solution to react for 10-14 hours to obtain an intermediate mixed solution; And continuously supplementi