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Carbon-coated lithium ion battery positive electrode material lithium iron phosphate and preparation method thereof

A carbon-coated technology for lithium iron phosphate and lithium ion batteries, applied in battery electrodes, chemical instruments and methods, circuits, etc., can solve the problems of low conductivity of lithium iron phosphate and lithium ion diffusion coefficient, etc. The effect of large capacity and cost reduction of production process

Inactive Publication Date: 2013-12-11
THE NAT CENT FOR NANOSCI & TECH NCNST OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method belongs to the low-temperature sol-gel method, which can easily control the LiFePO 4 The shape and size of the particle product, and the problem of low conductivity of lithium iron phosphate and low diffusion coefficient of lithium ions is overcome by carbon coating

Method used

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  • Carbon-coated lithium ion battery positive electrode material lithium iron phosphate and preparation method thereof
  • Carbon-coated lithium ion battery positive electrode material lithium iron phosphate and preparation method thereof
  • Carbon-coated lithium ion battery positive electrode material lithium iron phosphate and preparation method thereof

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0057] Dissolve 0.0024mol of citric acid and 0.0044mol of sucrose in 20ml of deionized water; dissolve 0.012mol of lithium carbonate in 80mL of deionized water; dissolve 0.024mol of ammonium dihydrogen phosphate and 0.024mol of ferric nitrate in 30ml and 60mL of deionized water; slowly add the lithium source, phosphorus source and ferric iron source to the mixed solution of citric acid and sucrose in turn, each solution needs to be stirred for a long enough time after adding, to ensure that each solution is added Finally, a uniformly mixed solution or suspension was obtained; the mixed solution was evaporated to dryness with magnetic stirring at a constant temperature of 80°C to obtain a precursor; the above precursor was pre-decomposed at 200°C for 2 hours; the pre-decomposed product was transferred to a high-temperature atmosphere furnace sintering at 650°C for 6h under the protection of argon or nitrogen, and cooling to room temperature with the furnace, the lithium iron pho...

Embodiment 2

[0061] Similar to Example 1, the preparation process of the precursor is exactly the same, the difference is that the condition of high temperature annealing is to sinter at 600°C for 6 hours under the protection of argon, and then cool to room temperature with the furnace to obtain the carbon-coated lithium-ion battery cathode material iron phosphate Lithium (LiFePO 4 ) nanoparticles.

[0062] X-ray powder diffraction analysis shows that the product is pure phase lithium iron phosphate (LiFePO 4 ); According to the scanning electron microscope analysis, the particle dispersibility of the product is good, and the particle size is about 150-220nm.

[0063] The product was used as the positive electrode material and assembled into an experimental button lithium-ion battery in an argon-protected glove box. The charge-discharge cycle was carried out between 2.0-4.2V at different rates. The 0.1C discharge capacity was 154mAh / g, and the 1C discharge capacity It is 123mAh / g, showin...

Embodiment 3

[0065] Similar to Example 1, the preparation process of the precursor is exactly the same, the difference is that the condition of high temperature annealing is to sinter at 700°C for 6 hours under the protection of argon, and then cool to room temperature with the furnace to obtain the carbon-coated lithium-ion battery cathode material iron phosphate Lithium (LiFePO 4 ) nanoparticles.

[0066] X-ray powder diffraction analysis shows that the product is pure phase lithium iron phosphate (LiFePO 4 ); According to the scanning electron microscope analysis, the particle dispersibility of the product is good, and the particle size is about 150-220nm.

[0067] The product was used as the positive electrode material, and assembled into an experimental button lithium-ion battery in an argon-protected glove box. The charge-discharge cycle was carried out between 2.0-4.2V at different rates. The 0.1C discharge capacity was 152mAh / g, and the 1C discharge capacity was 152mAh / g. It is 1...

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Abstract

The invention relates to a preparation method for a carbon-coated lithium ion battery positive electrode material. The preparation method comprises the following steps: successively adding a carbon source dispersion liquid, a phosphorus source dispersion liquid, a lithium source dispersion liquid and a ferric iron source dispersion liquid into a solution of a dispersant or deionized water; fully mixing an obtained mixed liquid so as to obtain a uniformly dispersed solution or turbid liquid; drying the mixed liquid to obtain a precursor and then pre-decomposing and sintering the precursor so as to obtain the single-phase carbon-coated lithium ion battery positive electrode material lithium iron phosphate. According to the method, usage of the ferric iron source enables cost for raw materials to be substantially reduced; process temperature of the synthesized material is low, high-temperature processing time is short, a preparation period for the material is substantially shortened, and production cost is effectively reduced; there is no requirement for raw materials, so the source of the raw materials is broadened. The synthesized lithium iron phosphate has the advantages of a particle size of 60 to 550 nm, good particle dispersion, high conductivity, great specific capacity, a long cycle life, etc. and can meet needs of practical application of a lithium ion battery.

Description

technical field [0001] The invention relates to the technical field of preparation of electrochemical power source materials. Specifically, the invention relates to a carbon-coated lithium ion battery positive electrode material lithium iron phosphate and a preparation method thereof. Background technique [0002] As a new generation of green high-energy batteries, lithium-ion batteries have been widely used in portable electronic devices, power tools, Energy storage devices, electric vehicles and hybrid electric vehicles. [0003] Lithium iron phosphate with olivine structure, due to its relatively high theoretical capacity (170mAh / g), long cycle life, stable structure, good safety performance, low cost, and no pollution, has become an ideal choice for the preparation of large-capacity, high-power power batteries. The cathode material for lithium-ion batteries with the most development potential has been commercially produced on a large scale and has gradually become the m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58H01M4/1397C01B25/45
CPCY02E60/10
Inventor 褚卫国田瑞源王汉夫
Owner THE NAT CENT FOR NANOSCI & TECH NCNST OF CHINA
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