Lithium iron phosphate/carbon composite electrode material and preparation method thereof

A lithium iron phosphate, composite electrode technology, applied in electrode manufacturing, battery electrodes, circuits, etc., can solve the problems of difficult particle size control, large particle size, long time consumption, etc. good coverage effect

Active Publication Date: 2009-08-12
CHENGDU ZHONGKE LAIFANG POWER SCI & TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the synthesis methods of lithium iron phosphate mainly include high-temperature solid-phase method, co-precipitation method, sol-gel method, etc. The high-temperature solid-phase method is prone to large particle size and component segregation; although the co-precipitation method solves the segregation phenomenon, the particle size Difficult to control; the reaction process of sol-gel method is difficult to control and takes a long time
[0003] However, the conductivity and ion diffusion rate of pure-phase lithium iron phosphate are low, which limits its application. In order to overcome the defect of low co...

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] Example 1 Preparation of lithium iron phosphate / C composite electrode material of the present invention

[0022] Add 10.7692g (0.2mol) lithium hydroxide to the three-necked flask, and neutralize it by titration with 18.4615g (0.2mol) of acrylic acid dissolved in 70.7692g of water. The titration process should be slow and constantly stirred. Polymerize under the action of initiator ammonium persulfate and chain transfer agent isopropanol. After the polymerization is completed, move the polymerization product into a ball mill tank, add iron phosphate according to the stoichiometric ratio and mix it. The mixture is ball milled for 6 hours and then dried. The resulting mixture was ball milled for another 6 hours. Weigh the ball-milled product and place it in a temperature-controlled reaction furnace replaced by non-oxidizing gas for calcination. The calcination condition is to raise the temperature from 20°C to 500°C, the heating rate is 10°C / min, keep the temperature at 50...

Embodiment 2

[0025] Embodiment 2 Preparation of lithium iron phosphate / C composite electrode material of the present invention

[0026] Other conditions were the same as in Example 1, except that the polyacrylic acid needed for the lithium carboxylate polymer was replaced by a poly(acrylic acid acrylonitrile) copolymer, wherein the ratio of acrylic acid:acrylonitrile was 8:2.

[0027] The electrical performance test method is the same as that of Example 1.

[0028] The Lithium Ferrous Phosphate / C material prepared by the method and proportioning in Example 2 is a black powder with uniform particle size. The discharge capacity is 116mAh / g at 0.2C, and 99mAh / g at 1C. The carbon content is 5.22%. .

Embodiment 3

[0029] Example 3 Preparation of lithium iron phosphate / C composite electrode material of the present invention

[0030] Add 10.7692g (0.2mol) lithium hydroxide to the three-necked flask, and neutralize it by titration with 18.4615g (0.2mol) of acrylic acid dissolved in 70.7692g of water. The titration process should be slow and constantly stirred. Polymerize under the action of initiator ammonium persulfate and chain transfer agent isopropanol. After the polymerization is completed, move the polymerized product into a ball mill tank, add iron phosphate according to the stoichiometric ratio and mix it. The mixture is ball milled for 6 hours and then dried. Weigh the ball-milled product and place it in a temperature-controlled reaction furnace replaced by non-oxidizing gas for calcination. The calcination condition is to raise the temperature from 20°C to 450°C at a heating rate of 10°C / min, keep it at 450°C for 2 hours, and then continue to heat up To 700°C, the heating rate is...

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Abstract

The invention relates to a novel lithium iron phosphate/C composite electrode material and a method for preparing the same, which belong to the technical field of lithium ion secondary batteries. The lithium iron phosphate/C composite electrode material is prepared by using iron phosphate as an iron source and a phosphonium source, using a macromolecular carboxylic acid lithium salt as a lithium source, using a carbon skeleton split product of the macromolecular carboxylic acid lithium salt as a carbon source, and performing solid phase reaction on the mixture of the iron phosphate and the macromolecular carboxylic acid lithium salt at a temperature of between 500 and 900 DEG C, wherein the mol ratio of lithium to iron to phosphate radical is 1-1.5:1:1, and the C content is 1 to 10 percent in percentage by weight. The carbon in-situ doping generated by the thermal decomposition of the macromolecular carboxylic acid lithium salt improves the electrical conductivity of lithium iron phosphate, and simultaneously the high viscosity of the macromolecular carboxylic acid lithium salt and the framework barrier effect of a thermal decomposition product can prevent component segregation, inhibit crystal grain growth, and are advantageous for improving the multiplying factor and the discharge performance of the material. The preparation method is simple and has good reproduction quality, and the lithium iron phosphate/C composite electrode material prepared by the method is black powder and has even granularity and high electrical conductivity.

Description

technical field [0001] The invention relates to a positive electrode material used as a lithium battery, a lithium ferrous phosphate lithium titanate / C composite electrode material and a preparation method thereof, belonging to the technical field of lithium ion secondary batteries. Background technique [0002] Lithium-ion secondary batteries have attracted people's attention due to their high voltage, no memory effect, high energy density, and good cycle performance. The positive electrode materials that determine the performance of lithium-ion batteries have always been a hot topic for researchers from all over the world. At present, lithium-ion battery cathode materials mainly include lithium cobaltate, lithium nickelate and lithium manganate. Due to the toxicity of cobalt and limited resources, the difficulty in preparing lithium nickelate, and the poor cycle performance and high-temperature performance of lithium manganate, it cannot meet the requirements of lithium-ion...

Claims

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Application Information

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IPC IPC(8): H01M4/36H01M4/58H01M4/38H01M4/04
CPCY02E60/12Y02E60/10
Inventor 潘中来邓正华杨克润林子吉索继栓
Owner CHENGDU ZHONGKE LAIFANG POWER SCI & TECH CO LTD
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