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Silicon/graphene composite thin film electrode and preparation method thereof and lithium ion battery

A technology of graphene composite and graphene film, which is applied in the direction of electrode carrier/current collector, battery electrode, secondary battery, etc., can solve the problems of poor silicon cycle stability, detachment, uneven composite, etc., and achieve high rate performance and ratio The effect of high capacity and high specific capacity

Inactive Publication Date: 2018-04-03
HUAWEI TECH CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, due to the high chemical stability of graphene and silicon, it is difficult to form a strong binding force, resulting in uneven recombination and the separation of silicon particles from the graphene conductive network after expansion, which has not fundamentally solved the problem of poor cycle stability of silicon. question

Method used

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  • Silicon/graphene composite thin film electrode and preparation method thereof and lithium ion battery
  • Silicon/graphene composite thin film electrode and preparation method thereof and lithium ion battery
  • Silicon/graphene composite thin film electrode and preparation method thereof and lithium ion battery

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preparation example Construction

[0052] Correspondingly, an embodiment of the present invention provides a method for preparing a silicon / graphene composite thin film electrode, comprising the following steps:

[0053] S10, providing a current collector, and performing a negatively charged current collector on the current collector to obtain a negatively charged current collector;

[0054] S20, providing a silicon material, and performing charge treatment on the silicon material to obtain a charged silicon material dispersion;

[0055] S30, providing graphene, and charging the graphene to obtain a graphene dispersion with an opposite charge to the silicon material;

[0056] S40. Alternately immerse the negatively charged current collector into the charged silicon material dispersion and the graphene dispersion oppositely charged to the silicon material, and act on the negatively charged current collector through electrostatic attraction Deposit a silicon film layer and a graphene film layer, and finally self...

Embodiment 1

[0071] A method for preparing a silicon / graphene composite film electrode, comprising the following steps:

[0072] S10, negatively charge the current collector: soak the purified copper foam current collector in 2wt% Ca(OH) 2 Soak in ethanol aqueous solution (the volume ratio of ethanol and water is 1:3) for 20min, and then wash repeatedly with ultrapure water to obtain a foamed copper current collector with a negative charge on the surface;

[0073] S20, positively charge the silicon material: Weigh 100 mg of silicon nanoparticles (D50 is 200-300 nm) and co-disperse with 100 mg of PDDA in 500 mL of deionized water, ultrasonically disperse for 30 min; centrifuge the dispersion and wash it repeatedly with deionized water Precipitate, to remove excess PDDA, disperse the washed product in deionized water, and prepare 100mL positively charged Si-PDDA dispersion;

[0074] S30. Negatively charge the graphene sheets: disperse the reduced and mechanically exfoliated graphene nanoshe...

Embodiment 2

[0078] A method for preparing a silicon / graphene composite film electrode, comprising the following steps:

[0079] S10. Negatively charge the current collector: soak the purified copper foil current collector in 1 wt% KOH ethanol aqueous solution (the volume ratio of ethanol and water is 2:3) for 5 minutes, and then wash it repeatedly with ultrapure water, A copper foil current collector with a negative charge on the surface is obtained;

[0080] S20, positively charge the silicon material: Weigh 500 mg of silicon nanoparticles (D50 is 500 nm) and co-disperse with 40 mg of PDDA in 200 mL of deionized water, ultrasonically disperse for 30 min; centrifuge the dispersion and wash the precipitate repeatedly with deionized water, To remove excess PDDA, disperse the washed product in deionized water to prepare 500mL positively charged Si-PDDA dispersion;

[0081] S30. Negatively charge the graphene sheets: disperse the reduced and mechanically exfoliated graphene nanosheets in dei...

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Abstract

The invention provides a silicon / graphene composite thin film electrode. The composite thin film electrode comprises a current collector and a silicon / graphene composite thin film formed on the current collector through electrostatic self-assembly; the silicon / graphene composite thin film comprises at least one silicon thin film layer and at least one graphene thin film layer which are stacked alternately; the silicon thin film layer is combined on the current collector or the graphene thin film layer through electrostatic attraction; and the graphene layer is combined on the current collectoror the silicon thin film layer through electrostatic attraction. The electrode has high structural stability, the electrode structure damage caused by silicon material expansion can be relieved effectively, and the cycle life of the battery can be prolonged; and the electrode has high specific capacity and high rate capability. The invention also provides a preparation method of the electrode, and a lithium ion battery comprising the electrode.

Description

technical field [0001] The invention relates to the technical field of battery electrode preparation, in particular to a silicon / graphene composite thin film electrode, a preparation method thereof, and a lithium ion battery. Background technique [0002] Compared with traditional secondary batteries, lithium-ion batteries have the advantages of high open circuit voltage, high energy density, long service life, small self-discharge, and no memory effect. They have been widely used in mobile electronic devices and electric vehicles. [0003] At present, the anode materials of lithium-ion batteries that have been commercialized are mainly carbon-based materials such as graphite, and their discharge capacity is basically around 350mAh / g, which cannot meet the demand for high energy density of lithium-ion batteries in the future. The silicon material has the largest known lithium intercalation capacity (4212mAh / g), which helps to increase the energy density of the battery, and i...

Claims

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Application Information

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IPC IPC(8): H01M4/133H01M4/134H01M4/1393H01M4/1395H01M4/36H01M4/38H01M4/583H01M4/64H01M10/0525B82Y30/00
CPCB82Y30/00H01M4/133H01M4/134H01M4/1393H01M4/1395H01M4/366H01M4/38H01M4/583H01M4/64H01M10/0525Y02E60/10
Inventor 杨婉璐王志勇夏圣安
Owner HUAWEI TECH CO LTD
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