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

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...

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