Method for testing mixing uniformity of positive electrode materials of lithium battery

Abstract

The invention relates to a method for testing mixing uniformity of positive electrode materials of a lithium battery. The method comprises the following steps: mixing lithium cobalt oxide with polyvinylidene fluoride and then carrying out heat treatment, and testing the volatilization rate of the polyvinylidene fluoride in a theoretical sample, so as to obtain the measured mass ratio of the polyvinylidene fluoride at any position in the mixture; comparing the measured mass ratio with a theoretical mass ratio of the polyvinylidene fluoride in an added raw material; and if the difference of thecomparison is within + / -0.05%, thus the positive electrode materials are uniformly mixed, and if the difference of the comparison is outside + / -0.05%, thus the positive electrode materials are not uniformly mixed. The method is simple in test process, good in repeatability and high in accuracy, is used for the lithium battery preparation process and can effectively improve the preparation efficiency, and can provide a guiding direction for the design of the mixing process.

Description

technical field [0001] The invention relates to the field of preparation of lithium batteries, in particular to a method for testing the mixing uniformity of positive electrode materials of lithium batteries. Background technique [0002] In the existing lithium battery production process, it is necessary to mix the positive electrode powder Lithium cobaltate (LCO) and polyvinylidene fluoride (Polyvinylidene Fluoride, PVDF) evenly, but there is no accurate and quantitative method for whether LCO and PVDF are evenly mixed. representation method. [0003] CN102661911A discloses a method for quickly detecting the mixing uniformity of powder materials. First, understand the various properties of the mixed materials, then take samples after mixing, and then calculate the deviation value through calculation, and then evaluate according to the size of the deviation value. When the deviation When the value is not greater than 10%, it is considered that the material has been mixed e...

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Problems solved by technology

[0003] CN102661911A discloses a method for quickly detecting the mixing uniformity of powder materials. First, understand the various properties of the mixed materials, then take samples after mixing, and then calculate the deviation value through calculation, and then evaluate according to the size of the deviation value. When the deviation When the value is not greater than 10%, it is considered that the material has been mixed evenly. If it is greater than 10%, it is necessary to continue mixing again, and then re-sampling and testing until the required deviation is reached; this scheme has the problems of complicated testing process and insufficient accuracy.

[0004] CN106404584A discloses a method for evaluating the uniformity of dry-mixing of lithium-ion battery powder, specifically adding dry powder materials and magnetic iron powder in the lithium-ion battery slurry to the mixer in turn for stirring; randomly taking out n parts of powder samples, each Each powder sample is weighed separately, and the magnetic iron powder in each powder sample is absorbed by a Gaussian magnetic rod, and then the remaining sample is weighed, and then the coefficient of variation of the mixing uniformity of the material is calculated according to the formula; If the obtained coefficient of variation CV is less than 10%, the dry mixing uniformity of the lithium-ion battery slurry powder is good; and the smaller the coefficient of variation, the more uniform the dry-mixing of the lithium-ion battery slurry powder. Defects in testing the homogeneity of mixtures containing magnetic materials in samples

[0005] Although the above-mentioned documents disclose some test methods for testing the mixing uniformity of materials, there are still problems that the test process is complicated and only applicable to the test of mixtures containing magnetic materials. Therefore, it is simple to develop a test method with high accuracy. And the test method suitable for the mixing uniformity test of lithium battery cathode materials is still of great significance

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