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LiFePO4 cathode material of lithium ion battery compositely coated by TiN and C and preparation method thereof

A lithium-ion battery and cathode material technology, applied in battery electrodes, circuits, electrical components, etc., can solve the problems of poor high-rate charge and discharge performance, achieve the effects of maintaining stability, reducing internal resistance, and improving electronic conductivity

Inactive Publication Date: 2012-10-10
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] The purpose of the present invention is to pass through lithium-ion battery cathode material LiFePO 4 Composite coating of TiN and C, which effectively overcomes the existing small amount of C-coated LiFePO 4 The shortcomings of the high-rate charge-discharge performance of the cathode material are poor, and a lithium-ion battery cathode material with excellent electrochemical performance (especially high-rate electrochemical performance) is provided.

Method used

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  • LiFePO4 cathode material of lithium ion battery compositely coated by TiN and C and preparation method thereof
  • LiFePO4 cathode material of lithium ion battery compositely coated by TiN and C and preparation method thereof

Examples

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Embodiment 1

[0024] LiFePO prepared by carbothermal reduction method 4 / C (C content 3.58wt%) powder was used as the matrix material, and the above-mentioned commercially available nano-TiN (d≈20nm) was used as the coating. Disperse 4.85 grams of matrix material in 160 grams of absolute ethanol (mass concentration 2.94wt%), disperse 0.15 grams of TiN in 40 grams of absolute ethanol (mass concentration 0.37wt%), and ultrasonically vibrate the above two suspensions respectively After 30 minutes it was stirred at room temperature for 3 hours. Under vigorous stirring, the TiN suspension was added dropwise to LiFePO 4 / C suspension, after the dropwise addition, continue to stir at 40~60°C for no less than 6 hours until excess ethanol is removed to obtain a paste, and then dried in an oven. The resulting powder was placed in a nitrogen-hydrogen mixed atmosphere in a tube furnace (V N2 :V H2 =95:5) heat treatment at 400°C for 2 hours, grinding, and passing through a 280 mesh sieve to obtain 3...

Embodiment 2

[0026] LiFePO prepared by carbothermal reduction method 4 / C (C content 3.58wt%) powder was used as the matrix material, and the above-mentioned commercially available nano-TiN (d≈20nm) was used as the coating. Disperse 4.80 grams of matrix material in 160 grams of absolute ethanol (mass concentration 2.91wt%), disperse 0.20 grams of TiN in 40 grams of absolute ethanol (mass concentration 0.50wt%), and oscillate ultrasonically for 30 minutes at room temperature Stir for 3 h; under vigorous stirring, add the TiN suspension dropwise to LiFePO 4 / C suspension, after the dropwise addition, continue to stir at 40~60°C for no less than 6 hours until excess ethanol is removed to obtain a paste, and then dried in an oven. The resulting powder was placed in a nitrogen-hydrogen mixed atmosphere in a tube furnace (V N2 :V H2 =95:5) heat treatment at 400°C for 2 hours, grinding, and passing through a 280 mesh sieve to obtain 4wt%TiN-coated LiFePO 4 / C / TiN powder. The battery was firs...

Embodiment 3

[0028] LiFePO prepared by carbothermal reduction method 4 / C (C content 3.58wt%) powder was used as the matrix material, and the above-mentioned commercially available nano-TiN (d≈20nm) was used as the coating. Disperse 4.75 grams of matrix material in 150 grams of absolute ethanol (mass concentration 3.07wt%), disperse 0.25 grams of TiN in 50 grams of absolute ethanol (mass concentration 0.50wt%), and oscillate ultrasonically for 30 minutes at room temperature Stir for 3 h; under vigorous stirring, add the TiN suspension dropwise to LiFePO 4 / C suspension, after the dropwise addition, continue to stir at 40~60°C for no less than 6 hours until excess ethanol is removed to obtain a paste, and then dried in an oven. The resulting powder was placed in a nitrogen-hydrogen mixed atmosphere in a tube furnace (V N2 :V H2 =95:5) Heat treatment at 400°C for 2 hours, grind, pass through a 280 mesh sieve, and obtain 5wt% TiN-coated LiFePO 4 / C / TiN powder. The battery was first charg...

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Abstract

The invention relates to a LiFePO4 cathode material of a lithium ion battery compositely coated by TiN and C, and a preparation method thereof. LiFePO4 powder coated by C is taken as a substrate, then TiN is coated on the surface of the substrate to form the LiFePO4 cathode material coated compositely by TiN and C; the mass percentage of C in the LiFePO4 coated by C is 1-10%, and the mass percentage of TiN in the LiFePO4 coated by TiN is 0.5-10%. A suspension coating method is adopted, a continuous uniform and complete electric conductive layer is formed on the surfaces of LiFePO4 particles by the composite coating of TiN and C, so that the internal resistance of the cathode material is remarkably reduced, the electro conduction rate is improved, and the diffusion rate of lithium ions is speeded up; the formation of the compositely coated layer is good for protecting and preventing the LiFePO4 particles not to be in direct contact with electrolyte as much as possible to reduce the corrosion by the electrolyte; in addition, as the TiN itself is high in hardness and excellent in chemical stability, the existence of the compositely coated layer can effectively prevent crystals from being fatigue and keep the stability of the structure in the repeatedly charge-discharge process, in particular the structural stability in the high-multiplying-power charge-discharge circumstances, and the high-multiplying-power electrochemical performance is improved.

Description

technical field [0001] The invention belongs to the technical field of positive electrode materials for lithium ion batteries, in particular to lithium iron phosphate (LiFePO 4 ) Cathode material and preparation method thereof. Background technique [0002] With the increasingly prominent energy and environmental issues, people are trying to find new energy sources that are non-polluting and recyclable. In a series of lithium-intercalated transition metal oxides that can be used as cathode materials for lithium-ion batteries—including layered LiMO 2 (M=Co, Ni, Mn) and LiM with spinel structure 2 o 4 (M=Co, Ni, Mn) and LiMPO with olivine structure 4 (M=Mn, Fe, Co, Ni), LiFePO with orthorhombic olivine structure 4 Cathode materials have gradually become a research hotspot at home and abroad. Studies have shown that this new type of cathode material has a series of advantages unmatched by other cathode materials: moderate working voltage, good cycle performance; large the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58
CPCY02E60/12Y02E60/10
Inventor 郭瑞松刘崇威安静李永
Owner TIANJIN UNIV