How does the detailed performance of the separator affect the lithium battery?

Regarding power lithium-ion batteries, the mechanical requirements in the assembly process make the required separator thicker, and the safety performance of power lithium-ion batteries is very important, and a thicker separator means better safety. The average thickness of the diaphragm is a particularly important quality indicator, which directly affects the appearance quality and the internal performance of the diaphragm roll, and it must be strictly controlled during the processing process. In a highly automated diaphragm processing line, the diaphragm thickness is automatically tested and controlled by a highly accurate online non-contact thickness gauge and a fast feedback control system. The thickness average of the diaphragm includes the longitudinal thickness average and the lateral thickness average. Among them, the lateral thickness average is particularly important, and it is generally required to be controlled within ±1 micron. 2. Air permeability resistance Theoretically speaking, the diaphragm is not a necessary part of the battery. It will only be added in the future to meet industrial processing. Therefore, the diaphragm must meet a very important performance: the electrochemical performance of the battery cannot be deteriorated, and the current internal resistance is important. 3. The pore size lithium battery diaphragm material itself has a microporous structure, and the distribution of micropores in the entire diaphragm material should be even. The electrode particles currently used are generally on the order of 10 microns, and the pore diameter is generally 0.03-0.12um. If the aperture is too small, resistance will be added. If the aperture is too large, it will easily make the positive and negative electrodes contact or be pierced by dendrites and short circuit. Generally speaking, the sub-micron pore size membrane is sufficient to prevent the electrode particles from passing straight through. Of course, it does not rule out that some electrode surfaces cannot be solved well, and some situations such as micro short circuits caused by more dust are not excluded. In order to ensure that the internal resistance of the lithium battery is not too large, the diaphragm is required to be able to be completely wetted by the electrolyte used in the battery. On the one hand, the degree of wettability is related to the diaphragm material itself, and on the other hand, the surface and internal microstructure of the diaphragm are closely related. Better wettability is beneficial to improve the affinity between the diaphragm and the electrolyte, expand the contact surface between the diaphragm and the electrolyte, thereby increasing the ion conductivity and improving the charge and discharge performance and capacity of the battery. 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 article: Which factors affect the performance of lithium batteries?