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Negative pole made of silicon/graphite nanosheet composite material of lithium ion battery and preparation method thereof

A technology of graphite nanosheets and lithium ion batteries, which is applied in electrode manufacturing, battery electrodes, active material electrodes, etc., can solve the problems of graphite nanosheets and silicon nanopowders that have not been published in literature reports, and avoid uneven mixing. Effect

Inactive Publication Date: 2009-12-02
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, so far, there have been no published literature reports on the composite negative electrode of this nano-graphite sheet and silicon nano-powder and its preparation.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] 1) Preparation of graphite oxide: disperse 2.0g of graphite into 46mL of concentrated sulfuric acid (0°C, ice bath), gradually add 6.0g of KMnO under constant stirring 4 , keeping the temperature below 20°C, and the mixture was continuously stirred for another 35 min. Change the ice bath to an oil bath, and then slowly add 92ml of deionized water. The addition of deionized water will cause the temperature of the mixture to rise, and maintain the temperature of the mixture at 98-100° C. for 20 minutes. Then continue to stir and slowly add 300ml deionized water to dilute and stop the reaction, then add 20ml 30% H 2 o 2 , so that the remaining KMnO 4 reduction. Centrifuge at 5000rpm, wash with 5% HCl solution several times to remove sulfate radicals therein, wash with deionized water and acetone three times respectively, and dry at 70° C. for 12 hours to obtain graphite oxide.

[0021] 2) Take 1.0g of graphite oxide and disperse it in 800mL deionized water again, and t...

Embodiment 2

[0028] 1) With the graphite powder of 2.0g, prepare graphite oxide by the 1st step method of embodiment 1.

[0029] 2) Take 1.0g of graphite oxide and disperse it in 500mL of deionized water again, and treat it with ultrasonic wave for 7 hours, so that the graphite oxide is peeled off into graphite oxide nanosheets to obtain a uniform dispersion system of graphite oxide nanosheets and water, and then add 1.4g of nano-silicon powder, and kept stirring for 5 hours, so that the nano-silica powder and graphite oxide nano-sheets are fully compounded and kept uniformly dispersed. The average particle diameter of silicon nanopowder is 50 nanometers.

[0030] 3) In the uniform dispersion system of the above-mentioned nano-silica powder and graphite oxide nano-sheets, add 15mL of hydrazine hydrate under stirring, then obtain the composite material of nano-silicon powder and graphite nano-sheets by step 3) in Example 1 . The composite material was characterized by TEM (transmission el...

Embodiment 3

[0034] 1) Preparation of graphite oxide: disperse 1.0g of graphite into 23mL of concentrated sulfuric acid (0°C, ice bath), gradually add 3.0g of KMnO 4 , keeping the temperature below 20°C, and the mixture was continuously stirred for another 30 min. Replace the ice bath with an oil bath, and then slowly add 46ml of deionized water. The addition of deionized water will cause the temperature of the mixture to rise, and maintain the temperature of the mixture at 98-100°C for 15 minutes. Then continue to stir and slowly add 140ml deionized water to dilute and stop the reaction, then add 10ml 30% H 2 o 2 , so that the remaining KMnO 4 reduction. Centrifuge at 5000rpm, wash with 5% HCl solution several times to remove sulfate radicals therein, wash with deionized water and acetone three times respectively, and dry at 70° C. for 12 hours to obtain graphite oxide.

[0035] 2) Take 0.5g of graphite oxide and disperse it in 500mL of deionized water again, and treat it with ultraso...

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Abstract

The invention discloses a negative pole made of a silicon / graphite nanosheet composite material of a lithium ion battery, which comprises the following components in percentage by mass: 85 to 95 percent of nanometer silicon powder-graphite nanosheet composite material, and 5 to 15 percent of polyvinylidene fluoride, wherein the content of nanometer silicon powder is between 20 and 75 percent in the nanometer silicon powder-graphite nanosheet composite material. A preparation method thereof comprises the steps of: preparing graphite oxide, preparing a mixed dispersion system of the nanometer silicon powder and graphite oxide nanosheets; adding a reducing agent, namely hydrazine hydrate into the mixed dispersion system of the nanometer silicon powder and the graphite oxide nanosheets, and reducing the graphite oxide nanosheets into graphite nanosheets to obtain a composite material of the nanometer silicon powder and the graphite nanosheets; and fully mixing the composite material of the nanometer silicon powder and the graphite nanosheets with N-methylpyrrolidone sol of the polyvinylidene fluoride, blending the mixture into paste, evenly coating the paste onto a copper coil, and performing drying and roller compaction. The negative pole made of the silicon / graphite nanosheet composite material of the lithium ion battery has high electrochemical capacity and good cycling stability performance.

Description

technical field [0001] The invention relates to a lithium ion battery electrode and a preparation method thereof, in particular to a silicon / graphite nanosheet composite negative electrode of a lithium ion battery with high capacity and stable cycle performance and a preparation method thereof, belonging to the technical field of inorganic materials. Background technique [0002] Lithium-ion batteries have excellent properties such as high specific energy, no memory effect, and environmental friendliness, and have been widely used in portable mobile appliances such as mobile phones and notebook computers. As a power battery, lithium-ion batteries also have broad application prospects in electric bicycles and electric vehicles. At present, graphite materials (such as: graphite microspheres, natural modified graphite and artificial graphite, etc.) are mainly used as negative electrode materials for lithium-ion batteries. These graphite materials have good cycle stability, but ...

Claims

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Application Information

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IPC IPC(8): H01M4/02H01M4/38H01M4/62H01M4/04
CPCY02E60/12Y02E60/10
Inventor 李辉陈卫祥常焜赵杰
Owner ZHEJIANG UNIV
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