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Preparation of modified graphite cathode material of lithium ion secondary battery

A secondary battery and graphite negative electrode technology, applied in battery electrodes, electrode manufacturing, circuits, etc., can solve the problems of poor high-current charge and discharge performance, low initial charge and discharge efficiency, poor electrochemical cycle performance, etc., and achieve good Improvement of cycle performance, reversible capacity, and stable capacity

Inactive Publication Date: 2008-08-20
ZHEJIANG UNIV
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  • Summary
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Problems solved by technology

However, due to some defects of natural graphite, its reversible capacity is not high, the electrochemical cycle performance is poor, the high current charge and discharge performance is not good, the first charge and discharge efficiency is not high, the compatibility with the electrolyte is poor, and the filling density is uneven. Low-level problems restrict the application of natural graphite as a negative electrode material in lithium-ion batteries

Method used

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  • Preparation of modified graphite cathode material of lithium ion secondary battery
  • Preparation of modified graphite cathode material of lithium ion secondary battery

Examples

Experimental program
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Effect test

Embodiment 1

[0020] Add 1 mol / L LiOH solution into an electrolytic cell with a volume of 0.9 liters, use barbed wire as the anode and nickel foam as the cathode, and electrolyze at a constant current of 2A for 1 hour at 0°C under stirring conditions to prepare ferrate Li 2 FeO 4 solution. In the prepared ferrate Li 2 FeO 4 Add 10 g of natural graphite to the solution, and carry out oxidation treatment for 1 h at 0° C. with stirring. Then aged at -10°C for 5 hours. The treated samples were washed with hydrochloric acid solution and deionized water, filtered with suction, and dried at 70° C. to obtain modified graphite. The modified sample obtained in this example has a 0.1C specific capacity of 310 mAh / g, and after 50 cycles, the capacity still maintains 85% of the highest capacity.

Embodiment 2

[0022] Add 20mol / L NaOH solution into a 0.9-liter electrolytic cell, use barbed wire as the anode and foamed nickel as the cathode, and conduct constant current 0.5A electrolysis at 100°C and stirring for 24 hours to prepare ferrate Na 2 FeO 4 solution. In the prepared ferrate Na 2 FeO 4 Add 20g of natural graphite into the solution, and carry out oxidation treatment at 100°C for 24h under stirring conditions. Then aged at 40°C for 72h. The treated samples were washed with phosphoric acid solution and deionized water, filtered with suction, and dried at 150° C. to obtain modified graphite. The modified sample obtained in this example has a 0.1C specific capacity of 345 mAh / g, and after 50 cycles, the capacity still increases steadily.

Embodiment 3

[0024] Add 5 mol / L LiOH solution and 1 g of natural graphite into an electrolytic cell with a volume of 0.9 liters, use barbed wire as the anode and nickel foam as the cathode, and conduct constant current 1A electrolysis at 70 ° C and stirring conditions for 10 h, using the prepared ferrate Li 2 FeO 4 In situ modification of graphite. Then aged at 20°C for 24 hours. The treated samples were washed with hydrochloric acid solution and deionized water, filtered with suction, and dried at 120° C. to obtain modified graphite. The modified sample obtained in this example has a 0.1C specific capacity of 330 mAh / g, and after 50 cycles, the capacity still maintains 90% of the highest capacity.

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Abstract

The present invention discloses a method for producing modified graphite anode material of lithium ion secondary battery which is obtained by liquid phase oxidation natural graphite by ferrate. The present invention employs liquid phase oxidation of natural graphite, has merits of low energy consumption, mid preparation conditions, easy control, uniform surface process. The ferrate oxidant is environment protection and cheap, the preparation condition is mid and easy to control. After oxidation treatment of ferrate, the reversible capacity of modified graphite is improved greatly and can reach to 300-440mAh / g, and good circle capability is shown, after 50 circulations, the capacity is stable yet.

Description

technical field [0001] The invention relates to battery electrode material technology, in particular to a preparation method of a modified graphite negative electrode material for a lithium ion secondary battery. Background technique [0002] Lithium-ion batteries have become one of the hottest research and development topics in the field of new secondary chemical power sources. The improvement of their performance mainly depends on their positive and negative active materials. In order to improve the performance of anode materials, many intercalation compounds have been studied, but the anode materials for commercial application are mainly graphite materials, among which synthetic graphite such as mesocarbon microspheres (MCMB) is the main one. However, synthetic graphite has disadvantages such as high price, relatively low electrochemical capacity (about 320mAh / g), and the generation of environmentally harmful gases during the synthesis process. Natural graphite has the c...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/58H01M4/04C01B31/04H01M4/583
CPCY02E60/10
Inventor 王建明沈宸丁平张鉴清
Owner ZHEJIANG UNIV
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