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

A composite cathode material, lithium iron phosphate technology, applied in the field of lithium ion batteries, can solve the problems affecting the rate performance of lithium iron phosphate materials, poor conductivity of lithium ion diffusion, poor lithium ion diffusion ability, etc., to avoid equipment and Huge energy consumption, avoiding enrichment or segregation, and improving the effect of diffusion capacity

Active Publication Date: 2021-06-11
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 its preparation method and application
  • Lithium iron phosphate composite positive electrode material and its preparation method and application
  • Lithium iron phosphate composite positive electrode material and its preparation method and application

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preparation example Construction

[0070] Such as figure 1 As described above, in one embodiment of the present invention, a method for preparing a lithium iron phosphate composite positive electrode material is provided, comprising the following steps:

[0071] S01, preparing 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, preparing a second solution, in which a carbon source and a doping metal salt are dissolved; the doping metal salt includes soluble aluminum salts, magnesium salts, chromium salts, zirconium salts, vanadium salts and cobalt salts one or more of

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

Embodiment 1

[0078] A preparation method of lithium iron phosphate composite cathode material, comprising the following steps:

[0079] (1) Add lithium carbonate, iron 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.

[0080] (2) take by weighing about 0.5% soluble ammonium metavanadate, cobalt nitrate etc. of mole percentage and enter into deionized water for dissolving, then add the carbon source that glucose and fructose form, wherein, the quality of carbon source accounts for lithium carbonate, 25% of the total mass of ferric nitrate and ammonium dihydrogen phosphate is fully stirred to form a 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...

Embodiment 2

[0085] A preparation method of lithium iron phosphate composite cathode material, comprising the following steps:

[0086] Same as Example 1, except that the molar percentage of doped metal salt is brought up to 2%, except that, other steps are all the same as Example 1, specifically comprising:

[0087] (1) Add lithium carbonate, iron 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) take by weighing about 2% soluble ammonium metavanadate, cobalt nitrate etc. of molar percentage and enter into deionized water and dissolve, then add the carbon source that glucose and fructose form, wherein, the quality of carbon source accounts for lithium carbonate, 25% of the total mass of ferric nitrate and ammonium dihydrogen phosphate is fully stirred to form a second solution; the molar ratio of ammonium metavanadate to cobalt nitrate is ...

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Abstract

The invention provides a lithium iron phosphate composite positive electrode material, comprising lithium iron phosphate composite nanoparticles and a carbon coating layer wrapped on the surface of the lithium iron phosphate composite nanoparticles; the lithium iron phosphate composite nanoparticles are uniformly distributed with Doping metal elements, 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 content of carbon element is 0.5% by mass -4.0%, the particle size of the lithium iron phosphate composite cathode material is 50nm-120nm. The lithium iron phosphate composite positive electrode material can greatly improve the diffusion capacity of lithium ions, reduce the concentration polarization of lithium ions during charge and discharge, and has outstanding rate performance. The invention also provides a preparation method and application of the lithium iron phosphate composite cathode 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 internationally recognized as ideal energy storage and output power sources due to their high volumetric energy density, mass energy density, and excellent cycle performance. increasingly important role. As an important part of the lithium-ion battery, the performance of the cathode material of the lithium-ion battery directly affects the various performance indicators of the lithium-ion battery, occupying the core position of the lithium-ion battery. At present, there are many kinds of cathode materials for lithium-ion batteries on the market. Among them, lithium iron phosphate (LFP) materials have good safety p...

Claims

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Application Information

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Patent Type & Authority Patents(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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