Silicon cathode material coated with graphene and preparation method thereof

Abstract

The invention relates to the technical field of lithium-ion cathode material, in particular to silicon cathode material coated with graphene and a preparation method of the silicon cathode material coated with the grapheme. The preparation method comprises the following steps: A, preparing oxidized graphene suspension liquid; B, preparing nanometer silicon particle suspension liquid; and C, preparing silicon cathode material coated with grapheme. The preparation method adopts the electrostatic self-assembly synthetic technology and is wide in source of raw material, low in price, simple in synthetic method, easy for control of process conditions, strong in operability and good in repeatability. The silicon cathode material coated with grapheme is high in specific capacity and good in cycle performance and rate capability, wherein the specific discharge capacity for the first time under the electric current density of 0.01-1.2V, 200mA / g can reach 2746mAh / g, and the specific discharge capacity after 100 times of cycles can maintain 803.8mAh / g.

Description

technical field

[0001] The invention relates to the technical field of lithium ion negative electrode materials, in particular to a graphene-coated silicon negative electrode material and a preparation method thereof. Background technique

[0002] Lithium-ion batteries are the most promising chemical batteries for energy storage because of their high energy density, high power density, and long service life. Although lithium-ion has been commercially available since 1990, its energy storage performance still cannot meet people's needs, especially in power batteries for electric vehicle power supplies that require greater energy density and power density. At the same time, as batteries widely used in portable electronic devices, lithium-ion batteries also need to continuously improve their performance to meet the ever-increasing performance requirements and market demands. Therefore, the development of high-performance lithium-ion batteries has become a research hotspot in r...

Examples

Embodiment 1

[0060] A preparation method of graphene-coated silicon negative electrode material, comprising the steps of:

[0061] A. Preparation of graphene oxide suspension: under the condition of ice-water bath, take 3.0g of graphite and add it to the mixed solution of 360mL sulfuric acid and 40mL concentrated phosphoric acid, stir evenly, and slowly add 6.0g potassium permanganate to the mixed solution , stirred evenly, then heated to 50°C, and mechanically stirred for 24h to obtain the reactant; cooled the reactant to room temperature and slowly poured into a mixture of 400mL ice water and 30mL hydrogen peroxide with a mass fraction of 30%, and then The mixed solution was centrifuged, washed with 500 mL of HCl with a mass fraction of 5%, and then washed with deionized water until the pH value was about 7, and the obtained product was vacuum-dried at a temperature of 50° C. to remove water to obtain graphite oxide; Weigh an appropriate amount of graphite oxide and disperse it into deio...

Embodiment 2

[0070] A preparation method of graphene-coated silicon negative electrode material, comprising the steps of:

[0071] A. Preparation of graphene oxide suspension: under the condition of ice-water bath, take 3.0g of graphite and add it to the mixed solution of 360mL sulfuric acid and 40mL concentrated phosphoric acid, stir evenly, and slowly add 6.0g potassium permanganate to the mixed solution , stirred evenly, then heated to 50°C, and mechanically stirred for 24h to obtain the reactant; cooled the reactant to room temperature and slowly poured into a mixture of 400mL ice water and 30mL hydrogen peroxide with a mass fraction of 30%, and then The mixed solution was centrifuged, washed with 500 mL of HCl with a mass fraction of 5%, and then washed with deionized water until the pH value was about 7, and the obtained product was vacuum-dried at a temperature of 50° C. to remove water to obtain graphite oxide; Weigh an appropriate amount of graphite oxide and disperse it in deioni...

Embodiment 3

[0079] A preparation method of graphene-coated silicon negative electrode material, comprising the steps of:

[0080] A. Preparation of graphene oxide suspension: under the condition of ice-water bath, take 3.0g of graphite and add it to the mixed solution of 360mL sulfuric acid and 40mL concentrated phosphoric acid, stir evenly, and slowly add 6.0g potassium permanganate to the mixed solution , stirred evenly, then heated to 50°C, and mechanically stirred for 24h to obtain the reactant; cooled the reactant to room temperature and slowly poured into a mixture of 400mL ice water and 30mL hydrogen peroxide with a mass fraction of 30%, and then The mixed solution was centrifuged, washed with 500 mL of HCl with a mass fraction of 5%, and then washed with deionized water until the pH value was about 7, and the obtained product was vacuum-dried at a temperature of 50° C. to remove water to obtain graphite oxide; Weigh an appropriate amount of graphite oxide and disperse it in deioni...

technical field

[0001] The invention relates to the technical field of lithium ion negative electrode materials, in particular to a graphene-coated silicon negative electrode material and a preparation method thereof. Background technique

[0002] Lithium-ion batteries are the most promising chemical batteries for energy storage because of their high energy density, high power density, and long service life. Although lithium-ion has been commercially available since 1990, its energy storage performance still cannot meet people's needs, especially in power batteries for electric vehicle power supplies that require greater energy density and power density. At the same time, as batteries widely used in portable electronic devices, lithium-ion batteries also need to continuously improve their performance to meet the ever-increasing performance requirements and market demands. Therefore, the development of high-performance lithium-ion batteries has become a research hotspot in r...

Examples

Embodiment 1

[0060] A preparation method of graphene-coated silicon negative electrode material, comprising the steps of:

[0061] A. Preparation of graphene oxide suspension: under the condition of ice-water bath, take 3.0g of graphite and add it to the mixed solution of 360mL sulfuric acid and 40mL concentrated phosphoric acid, stir evenly, and slowly add 6.0g potassium permanganate to the mixed solution , stirred evenly, then heated to 50°C, and mechanically stirred for 24h to obtain the reactant; cooled the reactant to room temperature and slowly poured into a mixture of 400mL ice water and 30mL hydrogen peroxide with a mass fraction of 30%, and then The mixed solution was centrifuged, washed with 500 mL of HCl with a mass fraction of 5%, and then washed with deionized water until the pH value was about 7, and the obtained product was vacuum-dried at a temperature of 50° C. to remove water to obtain graphite oxide; Weigh an appropriate amount of graphite oxide and disperse it into deio...

Embodiment 2

[0070] A preparation method of graphene-coated silicon negative electrode material, comprising the steps of:

[0071] A. Preparation of graphene oxide suspension: under the condition of ice-water bath, take 3.0g of graphite and add it to the mixed solution of 360mL sulfuric acid and 40mL concentrated phosphoric acid, stir evenly, and slowly add 6.0g potassium permanganate to the mixed solution , stirred evenly, then heated to 50°C, and mechanically stirred for 24h to obtain the reactant; cooled the reactant to room temperature and slowly poured into a mixture of 400mL ice water and 30mL hydrogen peroxide with a mass fraction of 30%, and then The mixed solution was centrifuged, washed with 500 mL of HCl with a mass fraction of 5%, and then washed with deionized water until the pH value was about 7, and the obtained product was vacuum-dried at a temperature of 50° C. to remove water to obtain graphite oxide; Weigh an appropriate amount of graphite oxide and disperse it in deioni...

Embodiment 3

[0079] A preparation method of graphene-coated silicon negative electrode material, comprising the steps of:

[0080] A. Preparation of graphene oxide suspension: under the condition of ice-water bath, take 3.0g of graphite and add it to the mixed solution of 360mL sulfuric acid and 40mL concentrated phosphoric acid, stir evenly, and slowly add 6.0g potassium permanganate to the mixed solution , stirred evenly, then heated to 50°C, and mechanically stirred for 24h to obtain the reactant; cooled the reactant to room temperature and slowly poured into a mixture of 400mL ice water and 30mL hydrogen peroxide with a mass fraction of 30%, and then The mixed solution was centrifuged, washed with 500 mL of HCl with a mass fraction of 5%, and then washed with deionized water until the pH value was about 7, and the obtained product was vacuum-dried at a temperature of 50° C. to remove water to obtain graphite oxide; Weigh an appropriate amount of graphite oxide and disperse it in deioni...

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