Modification method of artificial graphite

Abstract

The invention provides a modification method of artificial graphite. The modification method is characterized in that the process comprises the following steps of: step 1, crushing and sieving the artificial graphite; carrying out pre-oxidization treatment in an ice water bath, wherein an oxidant can be potassium permanganate, concentrated sulfuric acid or a mixed solution of potassium permanganate and concentrated sulfuric acid; the concentration of potassium permanganate is 0.1-5 M, the concentration of concentrated sulfuric acid is 12-18 M, the solute mol ratio ranges from 10: 1 to 1: 10 when the potassium permanganate and the concentrated sulfuric acid are mixed, and the pre-oxidization time is 1-10 hours; step 2, dissolving the product of the step 1 into a washing oil solution of asphalt; heating and agitating to carry out in-situ covering treatment; centrifuging and filtering, wherein the mass ratio of asphalt to washing oil is 0.01-0.4; the mass ratio of artificial graphite to asphalt is 10-100; the covering temperature is 120-200 DEG C; and the reaction time is 2-10 hours; and step 3, carbonizing the product of the step 2, wherein the carbonizing temperature is 800-1500 DEG C and the heat-preservation time is 2-12 hours.

Description

technical field [0001] The invention relates to the field of lithium-ion secondary batteries, in particular to a method for modifying artificial graphite in lithium-ion battery negative electrode materials. Background technique [0002] As one of the most commonly used negative electrode materials in the lithium battery industry, artificial graphite has the advantages of good crystal morphology, high specific capacity, and good conductivity; however, due to problems such as poor high-current performance, unsatisfactory cycle performance, and severe solvation of artificial graphite, So that the general graphite needs proper treatment to achieve the best results. [0003] Because pyrolytic carbon such as pitch has good cycle stability and good stability to organic electrolytes, it can make up for the defects of graphite in this respect. Therefore, many pyrolytic carbons coated with organic polymers on the surface of graphite form carbon-carbon composite material. In addition...

AI Technical Summary

Problems solved by technology

[0004] Japanese patent JP11246209 immerses and coats graphite in medium and low temperature asphalt, but it is difficult to form a uniform coating layer on the surface

However, JP200397357 directly mixes graphite and pitch, and then heat-treats it at high temperature. The pulverization of the post-treatment affects the particle size distribution of the product and also affects the coating effect.

Shanshan patent CN200410018079.7 is coated with a solvent, and then the solvent is removed in a vacuum and then thermally polymerized at 350-500°C. The performance of the obtained product is good, but the industrialization cost of high temperature and high pressure reaction is relatively high

And CN200510029448.7 improves the previous patent by adding reaction aids to improve the coating performance, but it does not solve the high temperature and high pressure problem

BAK patent CN200710072974.0 is oxidized by hydrogen peroxide or concentrated nitric acid, and then coated in asphalt solution. It can react at low temperature or even normal temperature, but the degree of oxidation is not enough, which makes the coating performance unsatisfactory. The cost of selected solvents such as pyridine and tetrahydrofuran is relatively low. High, difficult to meet industrial standards

[0005] Judging from the current situation, the existing technologies have not achieved satisfactory results from the perspective of industrialization, and there are generally disadvantages such as complex processes, high raw material costs, harsh reaction conditions, and unstable product quality.