Preparation method for graphite anode material of lithium ion battery

Abstract

The invention discloses a preparation method for a graphite anode material of a lithium ion battery. Fine graphite powder with a small particle size and an organic carbon source are taken as raw materials; through adoption of processes such as mixing, high temperature processing, graphitizing and sieving and through mixing of the fine powder and the organic carbon source in a heating environment, coating, kneading and secondary granulating effects can be realized; and under the adhering effect of the organic carbon source, the fine powder with the small particle size forms secondary particles. The anisotropy problem of the materials is solved, and the tap density of the materials is improved. According to the method, the turnover and device residual loss of the materials are reduced, the yield is high, the processes are simple, the energy consumption is low, the environment is protected, the surface coating effects of the materials are even, and the consistency is high. The prepared anode material is characterized in anisotropy, low iron impurity content, low initial irreversible capacity, low volume expansion, high liquid absorbency, high cycle performance, high cost performance and high comprehensive performance.

Description

technical field [0001] The invention belongs to the field of lithium-ion batteries, and in particular relates to a method for preparing a lithium-ion battery graphite negative electrode material. Background technique [0002] Lithium-ion batteries have the advantages of high voltage, large specific energy, long life and no memory effect. Therefore, in recent years, they have been widely used in 3C products, electric bicycles, energy storage systems, especially electric vehicles. Graphite anode materials are currently the dominant anode materials for commercial lithium-ion batteries, which have the advantages of low lithium insertion / extraction potential, high reversible capacity, abundant resources, and low price. [0003] Lithium-ion battery anode materials are currently mainly materials with a graphite structure, of which natural graphite is developing rapidly. Mesophase carbon microspheres are a kind of natural graphite, which has a stable structure, small specific surfa...

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Problems solved by technology

[0004] Chinese patents CN96198348.5 and CN03120199.6, etc. use pitch, petroleum tar, coal tar or their mixtures to coat graphite. The specific surface area of ​​pitch pyrolytic carbon is smaller than that of resin pyrolytic carbon coated graphite, and the affinity with graphite Good, the structure is stronger, but the asphalt coating will be deformed due to melting during the heating process, too much dosage will easily cause the coated graphite particles to stick to each other, too little dosage will easily cause coating unevenness, and it will easily expand during the heating process , affecting the electrical properties of graphite

However, due to the method of mixing up to four kinds of powders under normal temperature and solid phase conditions, it is difficult to ensure the uniformity of mixing the precursors of various coating materials. Secondly, among the two precursors, the soft carbon precursor The specific gravity is too high, so a second high-temperature graphitization treatment is required, otherwise the specific capacity of the final coated graphite material will be low due to the low degree of graphitization of soft carbon

This will eventually lead to an increase in the production cost of the product, making it difficult to meet the market's requirements for high-quality and low-cost products

[0007] Chinese patent CN201410325202.3 produces a natural graphite negative electrode material through physical processing, mixing, molding treatment, roasting treatment and spheroidizing and shaping of materials. The material turnover loss is large, the production efficiency is low, the energy consumption is large, and the process is complicated.

[0008] Chinese patent CN02125715.9 utilizes the method of spray granulation to coat a layer of carbon on the surface of graphite powder to obtain carbon-coated graphite powder with a core-shell structure of graphite inside and carbon outside. The first irreversible capacity is low and the cycle performance is good. , but the method is complicated, consumes a lot of energy, and has high production costs

[0009] Chinese patent CN200510029448.7 is a natural graphite negative electrode material obtained by coating the surface of natural graphite powder with an organic carbon source after roasting and other treatments. It is necessary to select aromatic solvents such as anthracene oil and washing oil as reaction aids. Anthracene oil and washing oil contain Anthracene, naphthalene, high-boiling phenols, heavy pyridine bases, acenaphthene, fluorene and other toxic substances are not friendly to the environment

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