Introduction to the performance and requirements of lithium battery separator materials

The advantage of the diaphragm performance determines the battery's interface structure and internal resistance, which in turn affects the battery's capacity, cycle performance, charge and discharge current density and other key characteristics. Excellent performance separators play an important role in improving the overall performance of lithium batteries. 1. Wetting ability and wetting speed: better wetting ability is beneficial to improve the affinity between the diaphragm and the electrolyte, expand the contact surface between the diaphragm and the electrolyte, thereby adding ion conductivity and improving the charge and discharge performance of the battery And capacity. The wettability of the diaphragm to the electrolyte can be measured by measuring its liquid absorption rate and liquid holding rate. 2. Chemical stability: The diaphragm should maintain long-term stability in the electrolyte and not react with the electrolyte and electrode materials. Its chemical stability is evaluated by measuring the corrosion resistance of the electrolyte and the rate of expansion and contraction. 3. Thermal stability: The battery will release heat during charging and discharging, especially when it is short-circuited or overcharged, a large amount of heat will be released. Therefore, when the temperature rises, the separator should maintain the original integrity and certain mechanical properties, and play the role of isolating the positive and negative electrodes and preventing short circuits. 4. Safety protection performance: With the gradual expansion of the application range of lithium batteries, especially in the field of power lithium-ion batteries, the safety of lithium batteries has become the most important link for lithium battery manufacturers. As the most critical core material of lithium batteries, higher requirements are also placed on the separator. Currently, separators for lithium batteries can generally provide an additional function, which is thermal shutdown. This feature can provide an additional safety protection for lithium batteries. The important parameters of this function are closed cell temperature and membrane rupture temperature. The many characteristics that lithium battery separators must have have put forward special requirements for their processing technology. The processing technology includes raw material formula and rapid formula adjustment, micropore preparation technology, and independent design of complete equipment. Among them, the microporous preparation technology is the core of the lithium battery separator preparation process, which is divided into dry uniaxial stretching, dry biaxial stretching and wet processes. With the rapid development of the lithium battery industry, the industry's demand for separators is also increasing. Therefore, the formulation of diaphragm standards should also be followed up in time. Regarding characteristic models of batteries, the selection of separator materials is very important. Choosing the right materials and specifications is a necessary condition for manufacturing high-quality 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 are the important differences between graphene batteries and graphene lithium batteries?