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Method for realizing carbon coating of lithium iron phosphate through radio frequency plasma enhanced chemical vapor deposition

A radio frequency plasma, lithium iron phosphate technology, applied in the direction of electrical components, battery electrodes, circuits, etc., can solve the problems of material energy density reduction, long chemical reaction time, small carbon powder density, etc., to achieve short reaction time and easy thickness Control, the effect of large specific capacity

Active Publication Date: 2011-05-18
SIHUI DABOWEN IND CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the low density of carbon powder, too much doping will lead to a decrease in the energy density of the material
And the chemical vapor deposition method in the prior art prepares carbon coating film (CN101237039, CN101217195) needs higher temperature (500-900 ℃) and longer chemical reaction time (5-48h)

Method used

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  • Method for realizing carbon coating of lithium iron phosphate through radio frequency plasma enhanced chemical vapor deposition
  • Method for realizing carbon coating of lithium iron phosphate through radio frequency plasma enhanced chemical vapor deposition
  • Method for realizing carbon coating of lithium iron phosphate through radio frequency plasma enhanced chemical vapor deposition

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] Weigh 0.078mol each of lithium dihydrogen phosphate, ferrous oxalate and citric acid according to n(Li):n(Fe):n(P):n(citric acid)=1:1:1:1 (by mole), Dissolve citric acid in 250ml of deionized water, dissolve the iron source, lithium source and phosphorus source in 100ml of deionized water respectively, add dropwise to the citric acid solution, stir vigorously at room temperature to form a sol, and evaporate the sol to dryness in a water bath at 80°C The precursor gel was obtained, and the precursor gel was vacuum-dried at 100°C for 8 hours to obtain a dry gel, which was ball milled for 3 hours, and then placed in a tube furnace protected by argon, and pretreated at 300°C for 10 hours to remove CO 2 and H 2 O. Cool to room temperature with the furnace, ball mill for 2h. Calcined at 750°C for 10h in an argon atmosphere (heating rate 2°C·min -1 ), cooling and ball milling to obtain LiFePO 4 / C. The prepared sample LiFePO 4 / C placed in Shenyang Xinlantian Plasma Enha...

Embodiment 2

[0029] Weigh lithium hydroxide, ferrous oxalate, ammonium dihydrogen phosphate and citric acid according to n(Li):n(Fe):n(P):n(citric acid)=1:1:1:1 (by mole) 0.078mol each, dissolve citric acid in 250ml deionized water, dissolve iron source, lithium source and phosphorus source in 100ml deionized water respectively, add dropwise to the citric acid solution, stir vigorously at room temperature to form a sol, steam in a water bath at 80°C After drying, a precursor gel was obtained, and the precursor gel was vacuum-dried at 100° C. for 8 hours to obtain a xerogel. Ball milled for 3 hours, placed in an argon-protected tube furnace, and pretreated at 300°C for 7 hours to remove CO 2 and H 2 O. Cool to room temperature with the furnace, ball mill for 2h. Calcined at 650°C for 20h in an argon atmosphere (heating rate 2°C·min -1 ), cooling and ball milling to obtain LiFePO 4 / C. The prepared sample LiFePO 4 / C placed in Shenyang Xinlantian Plasma Enhanced Chemical Vapor Deposit...

Embodiment 3

[0031] Weigh lithium chloride, ferrous sulfate, ammonium dihydrogen phosphate and citric acid according to n(Li):n(Fe):n(P):n(citric acid)=1:1:1:1 (by mole) Each 0.078mol, citric acid was dissolved in 250ml of deionized water, iron source, lithium source and phosphorus source were dissolved in 100ml of deionized water, respectively, added to the citric acid solution, stirred vigorously at room temperature to form a sol. The precursor gel was obtained after evaporating to dryness in a water bath at 80° C., and dried in vacuum at 100° C. for 8 hours to obtain a xerogel. Ball milled for 3 hours, placed in an argon-protected tube furnace, pretreated at 300°C for 8 hours, to remove CO 2 and H 2 O. Cool to room temperature with the furnace, ball mill for 2h. Calcined at 800 °C for 10 h in an argon atmosphere (heating rate 2 °C min -1 ), cooling and ball milling to obtain LiFePO 4 / C. The prepared sample LiFePO 4 / C placed in Shenyang Xinlantian Plasma Enhanced Chemical Vapor ...

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Abstract

The invention discloses a method for realizing carbon coating of lithium iron phosphate through radio frequency plasma enhanced chemical vapor deposition. The method comprises the following step of: putting lithium iron phosphate into a reaction chamber to make the lithium iron phosphate react for 15-60min in reactant gas under radio frequency plasma, wherein the total air pressure of the reaction chamber is maintained to be 8-30 Pa, the output power of the power supply of the radio frequency plasma is 40-100W, and the reactant gas is acetylene or the mixed gas of hydrogen and methane with a volume ratio of 1:1. A carbon-coated film generated by utilizing the method has the advantages of uniform component and easy control of the thickness as well as low temperature and short reaction timecompared with the carbon-coated film generated by utilizing the conventional chemical vapor deposition. A prepared carbon-coated LiFePO4 material has good crystal structure growth, no impurity phase in an XRD (X-Ray Diffraction) testing result, large specific capacity and excellent multiplying power performance and cycle performance. When the material forms a button type with metal lithium to simulate a battery test under the conditions of 0.5C and 1C, the discharge capacities for the first time are respectively 166.0mAh.g<-1> and 165mAh.g<-1>, and the capacity retention rates after 50 cyclesare respectively 99.5 percent and 99.3 percent.

Description

Technical field: [0001] The invention belongs to the technical field of lithium-ion battery cathode material preparation technology, in particular to a carbon-coated LiFePO prepared by radio frequency plasma enhanced chemical vapor deposition 4 / C method. Background technique: [0002] Lithium-ion secondary batteries have the advantages of high discharge voltage, no memory effect, high energy density, and excellent cycle performance, and are widely used in portable appliances, military and civilian equipment. In recent years, with the rapid increase in the use of lithium-ion batteries and the demand for lithium-ion batteries for electric vehicles, it is urgent to develop lithium-ion batteries with high safety, high energy density, high power, long cycle, high environmental protection and low price. Positive and negative electrode battery materials are an important factor affecting the overall performance and price of lithium-ion batteries. Relatively speaking, the research ...

Claims

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Application Information

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IPC IPC(8): H01M4/1397
CPCY02E60/12Y02E60/122Y02E60/10
Inventor 刘丽英陈彦伟闵德
Owner SIHUI DABOWEN IND CO LTD
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