Introduction of materials and electrolyte for lithium ion batteries diaphragm

　　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.

　　Comparison of the characteristics of PE products and PP products:

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

　　2. The density of PP is smaller than that of PE;

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

　　4. PP products are more brittle than PE;

　　5. PE 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 ion batteries.

　　Among the diaphragm material products for lithium ion 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 films at this stage. Technology and capabilities. The global automotive power lithium ion batteries use diaphragm materials such as three-layer PP/PE/PP, double-layer PP/PE, PP+ceramic coating, PE+ceramic coating and other diaphragm materials. 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 manufacturing of lithium ion batteries. 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 ion batteries diaphragm material products show a clear trend of diversification.

　　Lithium-ion battery electrolyte materials focus on high safety and high environmental adaptability, and the main development will focus on: new solvents (expanding working temperature range), ionic liquids, new lithium salts (improving environmental adaptability), additives (flame retardant, Redox shuttle, protection of positive and negative electrodes, film formation, etc.), matching with new positive and negative materials to improve safety, power and capacity, and finally safe and convenient application in electric vehicles, energy storage, aerospace and a wider range of fields .