Search

CN-121983563-A - High-power lithium iron phosphate positive electrode material and preparation method thereof

CN121983563ACN 121983563 ACN121983563 ACN 121983563ACN-121983563-A

Abstract

The application relates to the field of battery anode materials, in particular to a high-power lithium iron phosphate anode material and a preparation method thereof. In the application, the preparation is carried out by a carbon thermal sintering reduction method through iron, lithium, phosphorus, conductive precursors and a reducing agent together, and the coating performance between metal and carbon is improved through the conductive precursors, so that better electrochemical performance is obtained.

Inventors

  • WU GUAN
  • WU FANG

Assignees

  • 湖南泓原新能源科技有限公司

Dates

Publication Date
20260505
Application Date
20260407

Claims (10)

  1. 1. The preparation method of the high-power lithium iron phosphate anode material is characterized by comprising the following steps of: Mixing and precipitating raw materials, namely mixing an iron source, a lithium source, a phosphorus source, a conductive precursor accounting for 0.05-0.1 times of the iron amount and a reducing agent accounting for 0.05-0.1 times of the iron amount according to the mass ratio of 1:0.8-1.2:0.8-1.2 of iron to lithium, adding a solvent A, wherein the iron source is optionally ferric oxide or ferroferric oxide, the lithium source is optionally any of lithium carbonate, lithium chloride, lithium nitrate, lithium acetate and lithium hydroxide, and the phosphorus source is any of ammonium phosphate, diammonium phosphate and ammonium dihydrogen phosphate; the conductive precursor is resin with carbon content exceeding 70 wt%; grinding, namely ball milling the mixed system obtained in the step of mixing and precipitating the raw materials to obtain powder slurry; granulating, namely performing spray granulation on the powder slurry to obtain a spherical precursor; Sintering, namely sintering the spherical precursor in an oxygen-removing environment, wherein the sintering temperature is not higher than 800 ℃ to form a coating layer.
  2. 2. The preparation method of the high-power lithium iron phosphate positive electrode material according to claim 1, wherein the reducing agent comprises the following components in percentage by mass: 5-20% of hydroxypropyl methyl cellulose; 0.1-1% of aliphatic dicarboxylic acid; Reducing sugar balance.
  3. 3. The method for preparing a high-power lithium iron phosphate positive electrode material according to claim 2, wherein the substitution degree of the hydroxypropyl methylcellulose is 1.6-2.4.
  4. 4. The method for preparing a high-power lithium iron phosphate positive electrode material according to claim 2, wherein the hydroxypropyl methylcellulose has a weight average molecular weight of 50-100K.
  5. 5. The preparation method of the high-power lithium iron phosphate positive electrode material according to claim 2, wherein the solvent A is a mixed system of water and alcohol, the alcohol is optionally any of methanol, ethanol, ethylene glycol, propanol and propylene glycol, and the mass ratio of the water to the alcohol is 1:0.1-0.2.
  6. 6. The method for preparing a high-power lithium iron phosphate positive electrode material according to claim 2, wherein the aliphatic terminal dicarboxylic acid is any of 1, 6-adipic acid, 1, 7-pimelic acid, or 1, 8-suberic acid.
  7. 7. The method for preparing a high-power lithium iron phosphate positive electrode material according to claim 1, wherein the conductive precursor is any number of epoxy resins and phenolic resins.
  8. 8. The method for preparing the high-power lithium iron phosphate positive electrode material according to claim 1, wherein in the sintering step, preheating and sintering are performed firstly, wherein the preheating and sintering temperature is 300-400 ℃, the time is 2-4 hours, then the temperature is increased to high-temperature sintering, the temperature is 700-800 ℃, and the sintering time is 5-10 hours.
  9. 9. The method for preparing a high-power lithium iron phosphate positive electrode material according to claim 1, wherein in the grinding step, the viscosity of the powder slurry after grinding is 3500-5000 mpa.s.
  10. 10. The high-power lithium iron phosphate positive electrode material prepared by the method for preparing the high-power lithium iron phosphate positive electrode material according to any one of claims 1 to 9.

Description

High-power lithium iron phosphate positive electrode material and preparation method thereof Technical Field The application relates to the field of battery anode materials, in particular to a high-power lithium iron phosphate anode material and a preparation method thereof. Background Lithium iron phosphate batteries are the core solution of current power batteries, which have higher safety and longer cycle life, and currently occupy a larger market share. At present, the preparation method of the lithium iron phosphate battery anode material comprises two main flow routes of a solid phase method and a liquid phase method, wherein the solid phase method accounts for more than 70% of the market output. The solid phase method comprises a carbothermal reduction method and a high-temperature solid phase reaction method, wherein the carbothermal reduction method is obtained by sintering raw materials (comprising an iron source, a lithium source, a phosphorus source and a carbon source) at a high temperature, and the conductive precursor is used for reducing ferric iron into ferrous iron at a high temperature by utilizing the reducibility of the conductive precursor, and meanwhile, pyrolytic carbon forms a conductive coating layer on the surface of particles to form a conductive layer. The method has the advantages of simple raw materials, mature process and great convenience in mass production, and is the main production method at present. In the above process, the key to the carbothermic process is the uniformity of the coating, which is directly related to the resistance of the lithium iron phosphate battery and the power achievable. In order to improve uniformity, repeated grinding is usually needed in the granulating process, but the particle size distribution is difficult to control in the granulating process, so that the yield of the carbothermic reduction method in the preparation process is low, and the product quality is further affected. Disclosure of Invention The application provides a high-power lithium iron phosphate positive electrode material and a preparation method thereof in order to improve the stability of a carbothermic reduction method of the lithium iron phosphate positive electrode material and realize the effects of high power, high cycle times and high retention rate. Firstly, the preparation method of the high-power lithium iron phosphate anode material specifically comprises the following steps: Mixing and precipitating raw materials, namely mixing an iron source, a lithium source, a phosphorus source, a conductive precursor accounting for 0.05-0.1 times of the iron amount and a reducing agent accounting for 0.05-0.1 times of the iron amount according to the mass ratio of 1:0.8-1.2:0.8-1.2 of iron to lithium, adding a solvent A, wherein the iron source is optionally ferric oxide or ferroferric oxide, the lithium source is optionally any of lithium carbonate, lithium chloride, lithium nitrate, lithium acetate and lithium hydroxide, and the phosphorus source is any of ammonium phosphate, diammonium phosphate and ammonium dihydrogen phosphate; the conductive precursor is resin with carbon content exceeding 70 wt%; grinding, namely ball milling the mixed system obtained in the step of mixing and precipitating the raw materials to obtain powder slurry; granulating, namely performing spray granulation on the powder slurry to obtain a spherical precursor; Sintering, namely sintering the spherical precursor in an oxygen-removing environment, wherein the sintering temperature is not higher than 800 ℃ to form a coating layer. In the application, the ferric iron is reduced by adopting the reducing agent, and then the coating layer is formed on the surface of the ferric iron for processing, so that higher compaction density and better particle uniformity are provided, and meanwhile, the ash system in the system is further reduced, and the influence of the ash system on the resistance is reduced. On the basis of the above, the application adds a small amount of organic resin in the conductive precursor, and the particles are bonded and coated in the system through the organic resin, so that the reduction reaction can more easily and directly occur on the surfaces of the carbon particles, and further a better coating level is provided. The conductive particles can be carbon powder, graphite powder or graphene with specific size, and the conductive precursor should have certain cohesiveness so as to realize higher compaction density in the subsequent sintering process, and meanwhile, the branching property of the conductive precursor is utilized to improve the overall conductivity. In general, the organic resin should be selected to have a higher carbon content, which can form less ash and higher adhesion after sintering, and at the same time has a higher compaction density, preferably, the conductive precursor is any number of epoxy resins and phenolic resins, and the two resins can bond inorgani