Analysis of the difference between wet and dry diaphragms for lithium batteries

a. Because the process is simple, the investment in fixed assets is smaller than that of the wet method; however, it is difficult to control the temperature and other indicators of the production process in the dry method, and the wet method is simpler; b. The dry method can be used for three-layer film, while the wet method can only do Single-layer film; (The advantage of the three-layer film is that the thermal shutdown temperature is 135 degrees, but the thermal stability temperature is 160 degrees, which can prevent thermal inertia, and has 25 degrees of space, which is safer) c, dry and wet methods in addition to the production process Different, the raw materials used are also different. 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 exposed to heat. The safety is not suitable for high-power and high-capacity batteries; the wet method uses non-flowing, high-molecular-weight raw materials. The thermal shutdown temperature can reach 180 degrees, which can ensure the safety of high-power lithium batteries; d. In terms of processing general lithium batteries, dry method has advantages, low cost, less pollution, and more uniform holes; high-power batteries have wet methods Advantages, importantly, are safety and low heat shrinkability. Lithium battery dry process separators can be subdivided into uniaxial stretching process and biaxial stretching process. The dry uniaxial stretching process is a method of processing hard elastic fibers to prepare highly oriented polypropylene or polyethylene films with low crystallinity. In the high-temperature annealing process, a film with high crystallinity is obtained. This kind of film is first stretched at low temperature to form micro-defects, and then at high temperature, the defects are pulled apart to form micro-pores. At present, more than one-third of my country's output uses the dry double-drawing process, and products occupy a large proportion in the low-end market. 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 to form a uniform mixture, and then cools down for phase separation and compression Obtain the membrane, and then heat the membrane to a temperature close to the melting point, perform bidirectional stretching to align the molecular chains, and finally keep it warm for a certain period of time, eluting the residual solvent with volatile substances, and prepare interpenetrating microporous membrane materials. The wet processing technology can not only prepare interpenetrating microporous membrane materials, but also the processed lithium battery separator has higher longitudinal and lateral strength. At present, the wet processing technology is mainly used to process single-layer lithium battery separators. 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: Analysis of the difference between the characteristics of the soft and hard lithium battery packs