Coating slurry and coating process for lithium battery diaphragm

Abstract

The invention relates to a coating slurry for a lithium battery diaphragm and a coating process. The coating slurry comprises the following components in parts by weight: 35-55 parts of a copolymer emulsion, 25-40 parts of a titanium dioxide dispersion, and 3-6 parts of a dispersant 3-5 parts of chlorinated polypropylene and 1-4 parts of adhesive; the copolymer emulsion is a copolymer emulsion of tetrahydrofuran acrylate and butyl methacrylate; the coating process includes the following steps: S1. dispersing the copolymer emulsion and titanium dioxide Add liquid and chlorinated polypropylene to a magnetic stirrer and stir for 8-10min, then add a dispersant and continue stirring for 45-55min, and finally add an adhesive and stir for 25-35min to obtain a primary slurry for coating; S2. Perform ball milling treatment to obtain the finished slurry; S3. Place the diaphragm on a coating machine, and coat the finished slurry on the surface of the diaphragm at room temperature; S4. Place the diaphragm in an environment of 42-45°C for vacuum drying processing to obtain a coating-modified microporous membrane; S5. winding the coating-modified microporous membrane to obtain a finished product. The coating slurry in the present invention has good adhesion to the separator.

Description

technical field [0001] The invention relates to the technical field of processing lithium-ion battery diaphragm coating materials, in particular to a coating slurry and a coating process for lithium-ion battery diaphragms. Background technique [0002] Lithium-ion battery is a representative of modern high-performance batteries, consisting of four main parts: positive electrode material, negative electrode material, separator, and electrolyte. Among them, the diaphragm is a thin film with a microporous structure, which is a key inner component with technical barriers in the lithium-ion battery industry chain. The performance of the diaphragm determines the interface structure and internal resistance of the battery, which directly affects the capacity and cycle of the battery. As well as safety performance and other characteristics, the separator with excellent performance plays an important role in improving the overall performance of the battery. It plays the following two ...

AI Technical Summary

Problems solved by technology

[0003] The polyolefin microporous membrane has the following defects: the surface is hydrophobic, and the infiltration effect on the electrolyte is not good; the heat shrinkage temperature is not high, and when the temperature reaches above 130°C, there will be different degrees of volume shrinkage and cause internal short circuit

However, as the ceramic particle material is an inorganic material, there is no stress conduction between the particles, which seriously reduces the mechanical strength of the ceramic coating diaphragm, and its compatibility with the organic diaphragm is poor, resulting in a decrease in the adhesion between the ceramic particles and the organic diaphragm, resulting in The material falls off and the powder falls off, which reduces the high temperature resistance of the separator and affects the performance of the battery

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