The dry process primarily involves melting polyolefin resin, extruding it to form a crystalline polymer film, crystallizing it to obtain a highly crystalline structure, and then stretching it at high temperature to peel off the crystalline structure, forming a porous film. This method has mature equipment, a relatively simple process, and produces no pollution. The wet process primarily involves mixing liquid hydrocarbons or some high-boiling-point small molecules with polyolefin resin, melting them, and then preparing interconnected microporous membranes through processes such as extrusion, casting, biaxial stretching, and extraction.
As can be seen, the process of wet-process lithium-ion battery membranes is more complex than that of dry-process membranes, making them more suitable for high-power, high-capacity batteries. Increased subsidy thresholds, consumer demand for electric vehicles with long driving ranges, and stringent safety requirements have directly raised the requirements for battery capacity and power, thus creating more opportunities for the wet-process membrane market.
The manufacturing process of lithium-ion battery separators is complex and has high technological barriers. Separator manufacturing involves many processes, including raw material formulation and rapid formulation adjustment, micropore preparation technology, and independent design of complete sets of equipment. Among these, micropore preparation technology is the core of the lithium-ion battery separator manufacturing process. Based on the differences in micropore formation mechanisms, separator processes can be divided into dry and wet methods.
