Heat-resistant lithium ion battery coat separator and preparation method thereof

Abstract

A method for prepare a heat-resistant lithium ion battery coating separator comprise coating a heat-resistant organic polymer coating liquid on one or both side surfaces of a polypropylene lithium ionbattery base film, solidifying, pore forming and drying to obtain a heat-resistant lithium ion battery coating separator, wherein that heat-resistant organic polymer coating liquid is coated on one or both side surfaces of the polypropylene lithium ion battery base film; Heat-resistant organic polymer coating solution is mainly composed of heat-resistant organic polymer, pore-forming agent and water. The heat-resistant organic polymer is water-soluble phenolic resin, and the pore-forming agent is polyvinyl pyrrolidone or polyvinyl alcohol. The longitudinal shrinkage of the final product is <=3. 0% at temperature T, and the transverse shrinkage does not occur, and T >= 190 DEG C. The coating has a diameter of 30-70 nm micro-pore, in 180 degrees repeatedly fold more than 100 times the coating and the base film do not peel off. The preparation method of the invention has the advantages of simple process, low cost and good thermal stability of the prepared product.

Description

technical field [0001] The invention belongs to the field of lithium-ion batteries, and relates to a heat-resistant lithium-ion battery coating diaphragm and a preparation method thereof, in particular to a heat-resistant lithium-ion battery coating diaphragm with a water-soluble phenolic resin coating and a preparation method thereof. Background technique [0002] At present, a large number of commercial lithium-ion battery separators use polypropylene separators. Since the melting point of polypropylene is lower than 165°C, at higher temperatures, polypropylene will melt and become soft, and the polypropylene separator will shrink, causing short-circuit heating of the positive and negative electrodes of the lithium-ion battery, resulting in expansion, rupture and combustion of the lithium-ion battery , seriously affecting the safety of lithium-ion batteries. And, more importantly, once the current polypropylene separator is pierced, it will form a positive and negative sh...

AI Technical Summary

Problems solved by technology

However, on the one hand, the hardness of nano-inorganic particles is high, and there is still the possibility of piercing the diaphragm, which intensifies the wear and tear of processing equipment and increases production costs; on the other hand, nano-inorganic particles are insoluble in any solution system, which will cause uneven coating. Affect battery performance; In addition, the specific gravity of inorganic particles is relatively large, which significantly increases the weight of the separator