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Method for preparing expanded graphite/silicon carbon material from graphite negative electrode of waste battery

A technology of expanded graphite and silicon carbon materials, applied in the field of lithium ion batteries, can solve the problems of structural damage, reversible capacity of silicon anode materials, poor cycle stability and rate performance, active material shedding, etc., to reduce shedding and improve mechanical strength. and toughness, the effect of environmental protection in the recycling process

Inactive Publication Date: 2020-11-24
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the volume expansion effect of silicon during the charging and discharging process, its structure is destroyed, the active material falls off from the current collector, and an irreversible electrolyte film is continuously formed, which eventually leads to poor reversible capacity, cycle stability and rate performance of silicon anode materials.

Method used

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  • Method for preparing expanded graphite/silicon carbon material from graphite negative electrode of waste battery
  • Method for preparing expanded graphite/silicon carbon material from graphite negative electrode of waste battery
  • Method for preparing expanded graphite/silicon carbon material from graphite negative electrode of waste battery

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Experimental program
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Effect test

Embodiment 1

[0040] This embodiment includes the following steps:

[0041] (1) Pickling the graphite negative electrode of the waste lithium-ion battery at 40°C with a solid-to-liquid ratio of 1:80g / mL in sulfuric acid with a mass fraction of 2mol / L for 30min, filtering and drying to obtain a high-purity regenerated graphite material;

[0042] (2) Gained regenerated graphite material is placed in the mixed solution of oxidant and intercalant to react, graphite (g): intercalant (mL): oxidant (g)=1:10:0.3, wherein intercalant is Concentrated nitric acid and concentrated phosphoric acid, the volume ratio is 1:3, the oxidizing agent is potassium permanganate, stirred and reacted for 60 minutes, after the reaction is completed, washed with water until neutral, filtered, and dried to obtain expandable graphite;

[0043] (3) Put the obtained expandable graphite in a muffle furnace and roast at 900°C for 1 min to obtain expanded graphite; then the mass ratio of expanded graphite to silicon carbon ...

Embodiment 2

[0046] (1) Pickling the graphite negative electrode of the waste lithium-ion battery in 3mol / L trifluoroacetic acid at 40°C with a solid-to-liquid ratio of 1:80 for 30min, filtering and drying to obtain a high-purity regenerated graphite material;

[0047] (2) Gained regenerated graphite material is placed in the mixed solution of oxidizing agent and intercalating agent to react, graphite (g): intercalating agent (mL): oxidizing agent (g)=1:20:5, wherein intercalating agent is Concentrated sulfuric acid and concentrated phosphoric acid, the volume ratio is 1:3, the oxidant is potassium permanganate, stirred and reacted for 50 minutes, after the reaction is completed, washed with water until neutral, filtered, and dried to obtain expandable graphite;

[0048] (3) The obtained expandable graphite is placed in a muffle furnace and roasted at 1000°C for 30s to obtain expanded graphite; then the mass ratio of expanded graphite to silicon carbon material is 1:9, and the mass ratio of...

Embodiment 3

[0051] (1) Pickling the graphite negative electrode of the waste lithium-ion battery in 2mol / L trifluoroacetic acid at 40°C with a solid-to-liquid ratio of 1:80g / mL for 30min, filtering and drying to obtain a high-purity regenerated graphite material;

[0052] (2) Gained regenerated graphite material is placed in the mixed solution of oxidizing agent and intercalating agent to react, graphite (g): intercalating agent (mL): oxidizing agent (g)=1:10:0.5, wherein intercalating agent is Concentrated sulfuric acid, the oxidizing agent is potassium permanganate, stirred and reacted for 80 minutes, after the reaction was completed, washed with water until neutral, filtered, and dried to obtain expandable graphite;

[0053] (3) Put the obtained expandable graphite in a muffle furnace and roast at 1000°C for 30s to obtain expanded graphite; then, the mass ratio of expanded graphite and silicon carbon material is 2:8, and the mass ratio of ball milled bead powder is 20:1, and the mass ra...

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Abstract

The invention relates to a method for preparing an expanded graphite / silicon carbon material from a graphite negative electrode of waste battery. The method comprises the following steps of (1) takinga waste graphite negative electrode plate, and performing pickling, filtration and drying to obtain a graphite material; (2) mixing the graphite material obtained in the step (1) with an intercalating agent and an oxidizing agent for reaction, and then, performing water washing, filtration and drying to obtain expandable graphite; (3) placing and roasting the expandable graphite in a muffle furnace for a period of time to obtain expanded graphite; and (4) performing ball milling on the obtained expanded graphite and a silicon carbon material, and obtaining the expanded graphite / silicon carboncomposite material after the ball milling. According to the method provided by the invention, the pollution generated by the waste lithium ion battery is effectively reduced, and in addition, the waste graphite material of the negative electrode can be recycled and regenerated into an expanded graphite / silicon carbon composite negative electrode material. The regenerated material has the advantages of excellent mechanical strength and toughness, good cycle performance, great reversible capacity and high capacity retention rate.

Description

technical field [0001] The invention relates to the field of lithium-ion batteries, in particular to a method for preparing expanded graphite / silicon carbon materials from graphite negative electrodes of waste batteries Background technique [0002] Since the commercialization of lithium-ion batteries in 1990, they have been widely used in portable electronic devices such as mobile phones, notebook computers, and digital cameras due to their high capacity, light weight, good cycle performance, and low pollution. However, due to the rise of lithium-ion batteries, a large amount of graphite materials are used as battery electrodes, and there is a lack of reasonable recycling methods, resulting in a large amount of waste of graphite materials. [0003] At present, the commercial anode material is mainly graphite (MCMB), and its theoretical specific capacity is only 372mAh / g. Compared with the traditional graphite anode material, silicon has a very high mass specific capacity (4...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B32/225C01B32/05C01B33/02H01M10/54
CPCC01B33/02C01B32/05C01B32/225H01M10/54Y02W30/84
Inventor 欧星萧厚桂叶隆张佳峰张宝
Owner CENT SOUTH UNIV
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