Method for evaluating quality of coke for lithium battery negative electrode material

Abstract

The invention relates to a method for evaluating the quality of coke for a lithium battery negative electrode material, which comprises the following steps: S1, airing a green coke sample, performingcoarsely crushing, and completely performing screening by 4mm to obtain primary coke powder; s2, carrying out heat treatment on the primary coke powder in a nitrogen atmosphere at 700-800 DEG C, and then crushing the primary coke powder until the primary coke powder is completely sieved by a 0.071 mm sieve, so as to obtain secondary coke powder; and S3, carrying out vacuum drying on the secondarycoke powder at 110-140 DEG C, performing heating from 50 DEG C to 900 DEG C at a rate of 2-5 DEG C / min in an air atmosphere, carrying out thermogravimetric detection, and determining the reaction starting temperature of graphitization degree change and the reaction starting temperature of reversible capacity change. Compared with the prior art, the method has the beneficial effects that the quality grade of the green coke for the negative electrode can be rapidly distinguished, the sample consumption is small, and the analysis is rapid and sensitive; and compared with the traditional method, the method has the advantages of simplicity, convenience, time saving and the like in early-stage sample preparation.

Description

technical field [0001] The invention relates to the technical field of carbon materials, and relates to a method for rapidly evaluating the quality of coke used in negative electrode materials of lithium batteries, in particular to a method that can quickly evaluate the graphitization properties of coke used in negative electrodes and quickly estimate its reversible capacity . Background technique [0002] At present, lithium batteries have been widely used in various fields such as digital, energy storage, and power due to their characteristics of high energy density, good cycle performance, high rate performance, no memory, and no pollution. Lithium-ion battery negative electrode materials include natural graphite, artificial graphite (needle coke, pitch coke, petroleum coke, homogeneous coke, mesophase coke, mesophase carbon microspheres, etc.) The advantages of good liquid compatibility and cycle performance have attracted more and more attention from battery manufactur...

AI Technical Summary

Problems solved by technology

[0003] At present, the evaluation method of coke quality for negative electrodes is a big gap in China, and most suppliers continue to use traditional carbon material evaluation indicators, such as CTE, true density, volatile matter, ash, N, S content, etc., and these indicators are very important for lithium Battery negative electrode manufacturers are poorly targeted and have almost no guiding significance

Usually, negative electrode material manufacturers need to dry, pulverize, classify, and graphitize raw materials in the early stage, assemble them into button half cells, and perform charge and discharge tests to obtain the reversible capacity and first Coulombic efficiency of the material, and finally evaluate the coke based on these two contents. The quality grade of raw materials, but the detection period of this method is too long, which seriously affects the progress of the project, and most of the time is wasted on the selection of raw materials, so it is imminent to develop a method for quickly evaluating the quality of coke used in lithium battery negative electrode materials

[0004] The Chinese patent "A Rapid Evaluation Method for Coke Raw Materials" CN 107764681 A, although the general direction avoids the defect that the coke used in the negative electrode must be assembled into a half-cell before its quality can be evaluated, and the detection time is greatly shortened, the sample preparation in the early stage is too cumbersome. And there are certain requirements for the sample size, the parallelism of sample preparation and the introduction of other human errors will eventually lead to the real situation that the evaluation results are out of focus

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