Before 2001, the foreign diaphragm industry began to research on coated diaphragms. After 2005, CHINA only had a small number of patent applications for coated diaphragms. After 2010, related patents gradually increased. Coated separators mainly include:
1) Use PP microporous membrane as the base material , and ceramic material as the coating material, for single-sided or double-sided coating;
2) Use PE microporous membrane as the base material and ceramic material as the coating material single-sided or double-sided coating;
3) Diaphragm modified by coating based on polyethylene terephthalate film;
4) Diaphragms coated with heat-resistant polymers , etc. The coated diaphragm can improve the heat resistance, solve the problem of electrophile performance, prolong the cycle life, etc., and meet the requirements of the power lithium battery for the diaphragm .
Bai Yaozong et al[11] composite ceramic coatings on the upper surface or the upper surface and the lower surface of the polyolefin matrix microporous membrane , the thickness of the ceramic coating is 2-5 μm, and the total thickness of the green high-performance ceramic coating lithium battery separator 8 to 40 μm. The axial section of the pores on the polyolefin matrix microporous membrane is wavy, the porosity is 42%-52%, and the pore diameter is 0.15-1.50 μm. The lithium-ion battery manufactured by using the green high-performance ceramic coating diaphragm has good safety, which effectively solves existing lithium battery diaphragm ceramic coating peeling off, high temperature resistance and safety problems caused by the diaphragm of lithium-ion batteries; The lithium-ion battery diaphragm has high porosity, good electrolyte wettability, mechanical properties and temperature resistance, and also has shutdown protection performance, and can be widely used in power lithium-ion batteries. Xiao Wei et al. dispersed zeolite particles and binders in a solvent in proportion to obtain a uniform coating slurry, coated the slurry on both sides of , and dried it under a certain temperature to obtain a A high temperature resistant lithium battery separator with a novel inorganic coating. In the method, zeolite particles with excellent properties are added to the coating slurry . The zeolite material itself has extremely strong hydrophilicity and a developed three-dimensional pore structure, and the zeolite material has a crystal structure of aluminosilicate. Therefore, the high temperature resistance and electrolyte wettability of the separator are greatly improved . The lithium battery separator prepared by this method has the characteristics of superior comprehensive performance and high production efficiency, and can meet the needs of large-scale industrial production.
