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Preparation method of composite cathode material of lithium iron phosphate and carbon nano-tubes

A carbon nanotube composite and lithium iron phosphate technology, which is applied in battery electrodes, electrical components, circuits, etc., can solve the problems of low lithium ion diffusion speed and low conductivity of pure lithium iron phosphate, and achieve improved contact and strengthened conductive network , Improve the effect of electrical performance

Inactive Publication Date: 2010-05-19
辽宁凯信工业技术工程有限公司
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Problems solved by technology

Pure LiFePO 4 Only at extremely low charge-discharge rates (<C / 80) can there be reversible intercalation and deintercalation of 0.6 moles of Li, which is now mostly considered to be the reason for the low conductivity of pure lithium iron phosphate and the very low diffusion rate of lithium ions.

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  • Preparation method of composite cathode material of lithium iron phosphate and carbon nano-tubes
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  • Preparation method of composite cathode material of lithium iron phosphate and carbon nano-tubes

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Embodiment Construction

[0015] The preparation method of lithium iron phosphate and carbon nanotube composite cathode material comprises the following steps:

[0016] 1) Impurities in nanotubes mainly include amorphous carbon, iron, etc., so they need to be purified before use: heat carbon nanotubes in 4M nitric acid at 80°C for about 6 hours, and then undergo ultrasonication, filtration, and repeated cleaning until they are cleaned The pH value of the liquid is about 5.8;

[0017] 2) Prepare the precursor with citric acid, lithium nitrate, iron nitrate and ammonium dihydrogen phosphate as reactants. The specific process is: dissolve citric acid in an appropriate amount of deionized water, heat and stir at 80-90°C, and then add lithium nitrate and nitric acid in sequence The aqueous solution of iron and ammonium diammonium phosphate, the solution is brown and transparent, and the precursor is obtained;

[0018] 3) Take the above three parts of the same precursor, add carbon nanotubes to the precurso...

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Abstract

The invention relates to a preparation method of a composite cathode material of lithium iron phosphate and carbon nano-tubes. The preparation method comprises the following steps of: (1) preparing a precursor by taking citric acid, lithium nitrate, ferric nitrate, and ammonium dihydrogen phosphate as reactants; (2) adding the carbon nano-tubes to the precursor, wherein the mass percentage of the addition the carbon nano-tubes is 1-5 percent relative to the precursor, and thoroughly mixing the carbon nano-tubes with the precursor; (3) heating the mixed liquor of the carbon nano-tubes and the precursor, which treated in the step (2), in a constant temperature water bath with the temperature of 80-90 DEG C till solvent volatilize completely, pre-sintering the dried precursor at 250-350 DEG C for 8-10 hours under nitrogen atmosphere, and preserving the temperature at 700-800 DEG C for 8-10 hours to obtain the composite cathode material of the lithium iron phosphate and the carbon nano-tubes. Since the carbon nano-tubes are added into the sol-gel precursor, on the basis of active particulate carbon cladding provided by a sol-gel method, electric conduction network of carbon is enhanced though using the carbon nano-tubes to improve contacts among particles, thereby improving electrical property of a lithium ion battery.

Description

technical field [0001] The invention relates to the technical field of lithium ion batteries, and relates to a method for preparing a composite cathode material of lithium iron phosphate and carbon nanotubes. Background technique [0002] Lithium iron phosphate LiFePO 4 The material has the advantages of low cost, good environmental compatibility, high specific capacity, and good stability, and has become a positive electrode material for lithium-ion batteries with great application potential. [1～4] . Pure LiFePO 4 Only at an extremely low charge-discharge rate (<C / 80) can there be reversible intercalation of 0.6 moles of Li, which is now mostly considered to be the reason for the low conductivity of pure lithium iron phosphate and the very low diffusion rate of lithium ions. In order to improve the LiFePO 4 The modification methods that have been studied so far mainly include: lithium-site doping with high-valent metal ions, ultra-fine-graining and compounding of con...

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Application Information

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IPC IPC(8): H01M4/1397H01M4/62
CPCY02E60/12Y02E60/122Y02E60/10
Inventor 冯素萍吕霄
Owner 辽宁凯信工业技术工程有限公司
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