What are the differences between the dry and wet forming processes of lithium battery diaphragms?

1. The dry molding process needs to go through the steps of melt extrusion→high-stretching→cooling→thermal solution→stretching→heat setting→slitting and rewinding. The mold temperature machine controls the extrusion temperature during the melt extrusion process to ensure the material Of liquidity. The water chiller cools down the cooling roll during the cooling stage, and the mold temperature machine heats it up during the thermal solution stage. 2. Wet processing technology, also known as phase separation method or thermally induced phase separation method. The wet processing method mixes liquid hydrocarbons or some small molecular substances with polyolefin resin, heats and melts, forms an average mixture, and then cools down for phase separation , The membrane is compressed, and then the membrane is heated to a temperature close to the melting point, and the molecular chains are oriented by biaxial stretching. Finally, the temperature is kept for a certain period of time, and the residual solvent is eluted with volatile substances to prepare interpenetrating microporous membranes. material. 3. The wet processing technology of lithium battery diaphragm is complicated in equipment, large investment, long cycle, complicated process, high cost and high energy consumption. However, the size and distribution of the micropores are even, which is suitable for processing thinner products, and can only process a single layer of PE film. In terms of product quality, it has a higher nipple rate and better air permeability, which can meet the requirements of high current charging and discharging. 4. In addition to different production processes, dry and wet methods use different raw materials. The raw materials used in the dry method have good fluidity and low molecular weight, so the high temperature can only reach 135 degrees, and it will shrink when heated, and the safety is not suitable for high-power and high-capacity batteries; the wet method uses non-flowing, high-molecular-weight raw materials. The heat sealing temperature can reach 180 degrees, which can ensure the safety of high-power lithium batteries. Theoretically decomposing, the diaphragm processed by the dry biaxial stretching process is biaxially stretched. Under the condition that the longitudinal tensile strength is not much different, the transverse tensile strength is clearly higher than that of the diaphragm processed by the dry uniaxial stretching process. In terms of physical and mechanical properties, the dry uniaxial stretching process has more advantages. However, the lithium battery separator processed by the wet processing technology has high porosity and good air permeability, which can meet the requirements of high current charging and discharging of power lithium ion batteries. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: What technical route will accelerate the development of the energy storage lithium battery industry?