The market-oriented diaphragm materials are mainly polyethylene (PE) and polypropylene (polypropylene, PP)-based polyolefin (Polyolefin) diaphragms. Among them, PE products are mainly made by wet process, and PP products are mainly made of dry Method technology. As for the characteristics of the two materials, PE and PP.

Overall:

①PP is relatively more resistant to high temperature, while PE is relatively resistant to low temperature;

②PP has a lower density than PE;

③PP has higher melting point and closed cell temperature than PE;

④PP products are more brittle than PE;

⑤PE is more sensitive to environmental stress.

The main diaphragm material products include single-layer PP, single-layer PE, PP+ceramic coating, PE+ceramic coating, double-layer PP/PE, double-layer PP/PP and three-layer PP/PE/PP, among which the first two types of products Mainly used in the field of 3C small batteries, the latter types of products are mainly used in the field of power lithium batteries. Among the diaphragm material products for power lithium batteries, the double-layer PP/PP diaphragm material is mainly produced by Chinese companies and used in mainland China. This is mainly because no Chinese company can make PP and PE double-layer composite membranes at this stage. Technology and capabilities. The world's automotive power lithium battery separators are mainly composed of three-layer PP/PE/PP, double-layer PP/PE, PP+ceramic coating, PE+ceramic coating and other diaphragm material products.

At the same time, some other new diaphragm material products are also emerging and beginning to realize applications. However, due to the small quantity and high price, they are mainly used in the field of power lithium battery manufacturing. These products mainly include: coated polyester film (PET, Polyethylene Terephthalate), cellulose film, polyimide film (PI), polyamide film (PA), spandex or aramid film, etc. The advantages of these diaphragms are high temperature resistance, low temperature output, long charging cycle life, and moderate mechanical strength. In general, lithium battery separator material products show a clear trend of diversification.