Preparation method for artificial graphite negative electrode material for lithium ion battery

Abstract

Disclosed is a preparation method for an artificial graphite negative electrode material for a lithium ion battery. Artificial graphite coke powder with small grain diameter and an organic carbon source are taken as the raw materials; the raw materials are subjected to procedures of mixing, high-temperature treatment, graphitization treatment, sieving and the like; the coke powder and the organic carbon source are mixed in a heating environment, and the effects of coating, mixing and holding, secondary pelleting and the like can be achieved; the small-particle coke powder can form secondary particles under the cohesive action of the organic carbon source; therefore, the problem of anisotropy of the material is solved, and the tap density of the material is improved; meanwhile, the artificial graphite negative electrode material is capable of lowering the material turnover and equipment residual loss, high in yield, simple in procedures, low in energy consumption, environment-friendly, uniform in the coating effect on the surface of the material, and high in consistency; and in addition, the prepared negative electrode material has the characteristics of isotropy, low iron impurity content, low initial irreversible capacity, small volume expansion, high absorbency, high circulation performance, high performance cost ratio, excellent comprehensive performance and the like.

Description

technical field [0001] The invention belongs to the field of lithium ion batteries, and in particular relates to a preparation method of artificial graphite negative electrode materials for lithium ion batteries. 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, among which artificial graphite is developing rapidly. Mesophase carbon microspheres are a kind of artificial graphite. They have a stable struc...

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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 an artificial 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 an artificial graphite negative electrode material obtained by coating the surface of artificial graphite powder with an organic carbon source and then undergoing 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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