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Expanded graphite and nano-silicon composite material and preparation method thereof, electrode sheet, battery

A technology of expanded graphite and composite materials, applied in battery electrodes, nanotechnology, nanotechnology, etc., can solve the problems of low load, low tap density, low volume specific capacity, etc., achieve low energy consumption, high tap density, high The effect of volume to capacity

Active Publication Date: 2018-04-03
SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the tap density of carbon-nano-silicon composites prepared by existing methods is often very low, resulting in very little loading of electrode materials on the current collector, resulting in low volume specific capacity.

Method used

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  • Expanded graphite and nano-silicon composite material and preparation method thereof, electrode sheet, battery
  • Expanded graphite and nano-silicon composite material and preparation method thereof, electrode sheet, battery
  • Expanded graphite and nano-silicon composite material and preparation method thereof, electrode sheet, battery

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preparation example Construction

[0028] see figure 1 , the present invention provides a method for preparing a high-density expanded graphite and nano-silicon composite material 300, the high-density expanded graphite and nano-silicon composite material 300 can be applied to an electrode (not shown) of a lithium-ion battery, which includes the following steps .

[0029] In step S1, graphite is provided, and the graphite is oxidized by using concentrated sulfuric acid, potassium permanganate, and nitrate as an oxidizing agent to obtain graphite oxide, and the oxidation degree of graphite oxide is controlled by adjusting the amount of the oxidizing agent.

[0030] Specifically, the above step S1 includes the following steps.

[0031] Step S11, graphite, nitrate is added in the concentrated sulfuric acid according to certain proportion, at temperature T 1 Stir for a while 1 , to obtain a mixed solution.

[0032] Wherein the mass ratio of the graphite to the nitrate is 2:1, the mass ratio of the concentrated ...

Embodiment 1

[0054] Add 8g of phosphorus flake graphite and 4g of sodium nitrate into 200ml of concentrated sulfuric acid with a mass fraction of 98%, and stir at -5°C for 15 minutes to obtain a mixed solution; then slowly add 8g of potassium permanganate into the mixed solution, Stir at the temperature for 2 hours, then raise the temperature to 35°C, and continue to stir for 1 hour to obtain a precursor solution; add 400ml of water to the precursor solution, and raise the temperature to 98°C, stir for 2 hours, and then filter with suction to obtain an intercalated oxide graphite.

[0055] The above-mentioned graphite oxide with intercalation was heat-treated at 900° C. for 2 h under nitrogen protection atmosphere to obtain expanded graphite.

[0056] Weigh 100mg of the above-mentioned expanded graphite, 100mg of commercial nano-silicon, and 100mg of polyacrylonitrile into a ball mill jar, add 5g of grinding balls, then add 10ml of ethanol to wet the material, and ball mill at a speed of 4...

Embodiment 2

[0060] Add 8g of phosphorus flake graphite and 4g of sodium nitrate into 190ml of concentrated sulfuric acid with a mass fraction of 98%, and stir at -5°C for 15 minutes to obtain a mixed solution; then slowly add 16g of potassium permanganate into the mixed solution, Stir at the temperature for 1 hour, then raise the temperature to 35°C, and continue to stir for 1 hour to obtain a precursor solution; add 380ml of water to the precursor solution, raise the temperature to 98°C, stir for 2 hours, and then filter with suction to obtain an intercalated oxide graphite.

[0061] The above-mentioned graphite oxide with intercalation was heat-treated at 900° C. for 2 h under an argon protective atmosphere to obtain expanded graphite.

[0062] Weigh 200 mg of the above-mentioned expanded graphite, 100 mg of commercial nano-silicon, and 100 mg of polyacrylonitrile into a ball mill jar, add 8 g of grinding balls, then add 10 ml of ethanol to wet the material, and ball mill for 8 hours at...

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Abstract

The invention provides a preparation method of a high-density expanded graphite and nano-silicon composite material. The preparation method comprises the following steps: step S1, oxidizing graphite to manufacture graphite oxide; step S2, carrying out heat treatment on the graphite oxide to manufacture expanded graphite; step S3, mixing the expanded graphite with nano-silicon and a carbon source and carrying out ball-milling to obtain a high-density expanded graphite and nano-silicon composite material precursor comprising a plurality of graphite layers, the carbon source and the nano-silicon filled among the graphite layers; step S4, carrying out heat treatment on the high-density expanded graphite and nano-silicon composite material precursor so that the carbon source is converted into amorphous carbon; and step S5, depositing carbon or doped carbon on the surface of the high-density expanded graphite and nano-silicon composite material precursor after the heat treatment. Moreover, the invention also provides the high-density expanded graphite and nano-silicon composite material, an electrode plate applying the high-density expanded graphite and nano-silicon composite material, and a lithium ion battery applying the electrode plate.

Description

technical field [0001] The invention relates to a preparation method of expanded graphite and nano-silicon composite material, expanded graphite and nano-silicon composite material, an electrode sheet using the expanded graphite and nano-silicon composite material, and a lithium ion battery using the electrode sheet. Background technique [0002] Lithium-ion batteries are widely used in various electronic products and electric vehicles due to their high power density and high volume specific capacity. Silicon anode material has a very high specific capacity (4200mAh / g), good charge and discharge platform and low lithium intercalation potential, making it an ideal material to replace graphite as the anode material of lithium-ion batteries. However, the volume of silicon materials will expand to 300% of the initial volume during the process of lithium intercalation. Repeated cycles of lithium intercalation and delithiation will lead to electrode pulverization, which will deter...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M4/36H01M4/38H01M4/62H01M10/0525B82Y30/00
CPCB82Y30/00H01M4/366H01M4/386H01M4/625H01M10/0525Y02E60/10
Inventor 贺艳兵黄昱颖韩达韵勤柏柳明秦显营李宝华康飞宇
Owner SHENZHEN GRADUATE SCHOOL TSINGHUA UNIV
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