The role of 18650 battery coating separator, the development of 18650 battery separator technology

　　The role of 18650 battery separator coating, the development of 18650 battery separator technology. In recent years, with the development of my country's new energy industry and the continuous improvement of 18650 battery production technology, my country's demand for lithium-ion battery separators has also been growing. In recent years, the proportion of coating films in the market demand for 18650 battery separators has continued to increase. In the future, composite separator materials will also be an important means to improve performance.

　　The role of lithium-ion battery separators

　　The lithium-ion battery separator is called the "third pole". The important role of the separator on the overall performance of the 18650 battery is embodied in the following three aspects: Isolating the positive and negative electrodes of the battery. The separator itself is non-conductive and can prevent electrons in the battery from passing through to prevent the two poles from contacting and causing a short circuit; it allows lithium ions to pass through. The micropores on the separator allow lithium ions to be transported between the positive and negative electrodes to complete the electrochemical charge and discharge process; preventing battery explosion caused by high temperature. When a 18650 battery overheats, the micropores on the separator close, preventing lithium ions from passing through, and the internal resistance of the battery rises to 2KΩ, forcing the battery to stop charging and discharging.

　　The role of 18650 battery coating separator

　　Coated (or composite) diaphragms are the focus of today's diaphragm application development. The advantages of using a coating layer on the surface of the diaphragm are obvious. The first is to improve the thermal stability of the separator. For example, after ceramic coating, the separator still maintains its shape at high temperatures of 180°C, which can avoid internal short circuits caused by shrinkage of the separator and significantly improve battery safety;

　　The second is to improve the wettability of the separator to the electrolyte, which is beneficial to reducing the internal resistance of the 18650 battery and increasing the discharge power;

　　Furthermore, it can prevent or reduce the oxidation of the separator, which is beneficial to the operation of high-voltage positive electrodes and extending the cycle life of lithium batteries;

　　Separator coating improves lithium-ion battery performance.

　　Excellent separators play a very important role in improving the overall performance of lithium batteries. Their performance affects the structure, resistance, capacity, cycle and safety performance of the battery, especially the puncture resistance, self-shutoff, high temperature resistance and other properties of the separator. It is the main guarantee for the internal safety of the battery.

　　Coating technology separator technology can effectively improve the comprehensive performance of 18650 battery separators. Coating can significantly improve the performance deficiencies of wet separators such as poor high temperature resistance. "Wet + coating technology" while retaining the excellent mechanical strength properties of wet separators, improves the shortcomings of low melting point and poor safety of non-coated wet separators, making it more suitable for preparing high energy density power batteries.

　　Development of 18650 battery separator technology

　　It is reported that the separator is a high value-added material with the highest technical barriers among 18650 battery materials, accounting for about 15% of the cost of lithium batteries. The technical difficulties lie in the engineering technology of pore creation, matrix materials, and manufacturing equipment. In recent years, the localization rate of my country's 18650 battery separators has continued to increase, but it mainly occupies the low-end 3C battery separator market. The localization rate of high-end separators is still very low. High-end 3C batteries and power battery separators still rely heavily on imports.

　　There are currently four main industrial separator manufacturing technologies: wet method, dry method, semi-dry method and non-woven method. As domestic separator production capacity continues to expand, the downward trend in prices is irreversible. A common problem with domestic Lide diaphragm technology is that the consistency needs to be improved. Consistency is mainly reflected in irregular defects, thickness, porosity, pore distribution and pore size distribution. The porosity and pore size distribution of uniaxially stretched domestic PP separators are relatively close to benchmark products; the porosity of bidirectional step-stretched PE separators is usually lower than benchmark products, and the pore size distribution is not ideal.

　　Through patent statistical analysis, it can be found that although most industrialized 18650 battery separator materials are polyethylene and polypropylene, some polymer materials with better performance have also been gradually developed in laboratories, such as vinylidene fluoride (PVDF). , polyimide (PI), aramid and cellulose, etc., the types of separator materials will develop in a diversified direction.

　　Summary: Based on the country’s strong support for the new energy vehicle industry and the independent and active development trend of enterprises in the industry, it is believed that the 18650 battery and related materials industry will accelerate development in the medium to long term. 18650 battery separators can be optimistic about 5 to 15 years or even longer.

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