The important steps and principle analysis of dry and wet lithium battery separator process

1. The dry method first melts, extrudes and blows the polyolefin resin to form a crystalline polymer film, and then performs crystallization heat resolution and annealing operations to obtain a highly oriented film structure, and then stretches it at high temperatures. Detect the separation of the crystalline cross section to form a porous structure battery separator. The dry process can also be divided into uniaxial stretching and biaxial stretching. 2. Wet method The traditional wet method is mainly based on phase inversion method, and in recent years, TIPS thermally induced phase separation method is the main method. The principle is to mix crystalline polymers, thermoplastic polymers, and small molecular chemical diluents with high boiling points (such as paraffin oil) to form a homogeneous solution at high temperatures, and then lower the temperature of the solution to separate the mixture from solid and liquid. Or liquid-liquid separation, after the small molecule chemical diluent is extracted and removed, a porous membrane of thermoplastic and crystalline polymer is formed. The key features of the wet process are high cost, large investment, high equipment requirements, long construction and production cycle, high energy consumption during processing, and the use of organic solvents. However, the wet process can better control the pore size, distribution and porosity, so it is generally used to manufacture high-end films. Compared with foreign companies, the diaphragms processed by domestic companies are mainly dry-stretched, and most of them are low-end products. High-end wet-process diaphragms have been monopolized by foreign companies for many years. However, in recent years, as domestic diaphragm processing companies continue to improve the wet processing technology, the output and performance of wet diaphragms are getting closer and closer to the level of foreign companies. Domestic companies have rapidly expanded the production of wet diaphragms, and the pattern of the diaphragm market has also occurred. Variety. As one of the four major materials of lithium batteries, the separator does not participate in the electrochemical reaction in the battery, but the key properties of the battery, such as the capacity, cycle performance, and charge-discharge current density, have a direct relationship with the separator. Diaphragm is an important part of lithium battery, and it is an important component that supports lithium battery to complete the electrochemical process of charging and discharging. It is located between the positive and negative electrodes inside the battery to ensure the passage of lithium ions while obstructing the transmission of electrons. The performance of the separator determines the interface structure and internal resistance of the battery, which directly affects the battery's capacity, cycle and safety performance. The excellent performance of the separator has an important purpose for improving the overall performance of the lithium battery. Disclaimer: Some pictures and content of the articles published on this site are from the Internet. If there is any infringement, please contact to delete. Previous: What are the uses of the lithium battery pack?