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Lithium iron phosphate composite positive electrode material and preparation method and application thereof

A composite cathode material, lithium iron phosphate technology, applied in the field of lithium ion batteries, can solve the problems of poor lithium ion diffusion ability, poor rate performance, affecting the rate performance of lithium iron phosphate materials, etc., to achieve superior charge and discharge rate performance, high capacity retention rate effect

Active Publication Date: 2019-08-02
FOSHAN DYNANONIC
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Lithium iron phosphate material with olivine structure has severe polarization, low capacity retention rate and poor rate performance during high current charge and discharge process due to its poor conductivity and lithium ion diffusion ability.
The electronic conductivity of the material can be effectively improved by surface carbon coating, and the resistivity can be reduced from ~10 9 Ω·cm drops below 10Ω·cm, but its lithium ion diffusion ability is still poor, seriously affecting the rate performance of lithium iron phosphate materials

Method used

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  • Lithium iron phosphate composite positive electrode material and preparation method and application thereof
  • Lithium iron phosphate composite positive electrode material and preparation method and application thereof
  • Lithium iron phosphate composite positive electrode material and preparation method and application thereof

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preparation example Construction

[0070] Such as figure 1 As mentioned, in one embodiment of the present invention, a method for preparing a lithium iron phosphate composite cathode material is provided, which includes the following steps:

[0071] S01: Prepare a first solution in which a lithium source, an iron source, a phosphorus source and a complexing agent are dissolved, and the pH of the first solution is less than or equal to 4;

[0072] S02, prepare a second solution in which a carbon source and a doping metal salt are dissolved; the doping metal salt includes soluble aluminum salt, magnesium salt, chromium salt, zirconium salt, vanadium salt and cobalt salt. One or more of

[0073] S03: After heating the first solution to 40-100°C, slowly add the second solution to the first solution, stop heating and stir evenly to obtain a mixed solution, the mixed solution undergoes an exothermic reaction, so After the solvent in the mixed solution is evaporated by the heat released by the exothermic reaction, a precurs...

Embodiment 1

[0078] A method for preparing lithium iron phosphate composite cathode material includes the following steps:

[0079] (1) Lithium carbonate, ferric nitrate and ammonium dihydrogen phosphate with a molar ratio of 1:1:1 are added to the nitric acid solution, and a citric acid complexing agent is added to adjust the pH to 3 to prepare the first solution.

[0080] (2) Weigh soluble ammonium metavanadate, cobalt nitrate, etc. with a molar percentage of about 0.5% into deionized water to dissolve, and then add a carbon source composed of glucose and fructose, where the mass of the carbon source accounts for lithium carbonate, 25% of the total mass of ferric nitrate and ammonium dihydrogen phosphate, mix well and form the second solution; the molar ratio of ammonium metavanadate to cobalt nitrate is 2:1; the volume ratio of the second solution to the first solution It is 1:3.

[0081] (3) Turn on the heating, heat the first solution to 80°C, slowly pour the second solution into the first ...

Embodiment 2

[0085] A method for preparing lithium iron phosphate composite cathode material includes the following steps:

[0086] Same as Example 1, except that the mole percentage of doped metal salt is increased to 2%. Except for this, the other steps are the same as Example 1, specifically including:

[0087] (1) Add lithium carbonate, ferric nitrate and ammonium dihydrogen phosphate in a molar ratio of 1:1:1 to the nitric acid solution, and add a citric acid complexing agent to adjust the pH to 3 to prepare the first solution.

[0088] (2) Weigh soluble ammonium metavanadate, cobalt nitrate, etc. with a molar percentage of about 2% into deionized water for dissolution, and then add a carbon source composed of glucose and fructose, where the mass of the carbon source accounts for lithium carbonate, 25% of the total mass of ferric nitrate and ammonium dihydrogen phosphate, mix well and form the second solution; the molar ratio of ammonium metavanadate to cobalt nitrate is 2:1; the volume rati...

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Abstract

The invention provides a lithium iron phosphate composite positive electrode material, which comprises lithium iron phosphate composite nanoparticles and a carbon coating coated on the surfaces of thelithium iron phosphate composite nanoparticles, wherein doping metal elements are evenly distributed in the lithium iron phosphate composite nanoparticles, and the doping metal elements include one or more of aluminum, magnesium, chromium, zirconium, vanadium and cobalt. In the lithium iron phosphate composite positive electrode material, the mass percentage content of the carbon element is 0.5%-4.0%, and the particle size of the lithium iron phosphate composite positive electrode material is 50nm-120nm. The lithium iron phosphate composite positive electrode material can greatly improve thediffusion ability of lithium ions, reduce the concentration polarization of the lithium ions during the charging and discharging process and has outstanding rate performance. The invention further provides a preparation method and an application of the lithium iron phosphate composite positive electrode material.

Description

Technical field [0001] The invention relates to the field of lithium ion batteries, in particular to a lithium iron phosphate composite positive electrode material and a preparation method and application thereof. Background technique [0002] Under the international background of resource scarcity and energy saving and emission reduction, lithium-ion batteries are recognized internationally as ideal energy storage and output power sources due to their high volume energy density, mass energy density and excellent cycle performance. Increasingly show an important role. As an important part of lithium-ion batteries, the performance of the cathode materials of lithium batteries directly affects the performance indicators of lithium batteries, occupying the core position of lithium-ion batteries. At present, there are many kinds of cathode materials for lithium-ion batteries on the market. Among them, lithium iron phosphate (LFP) material has good chemical stability and structural s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/36H01M4/58H01M4/62H01M10/0525B82Y30/00
CPCB82Y30/00H01M4/366H01M4/5825H01M4/625H01M4/626H01M10/0525H01M2004/021H01M2004/028Y02E60/10
Inventor 石忠洋陈燕玉张世庆任望保
Owner FOSHAN DYNANONIC
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