High-end separator technology for lithium batteries is a core threshold. High-end separator technology for lithium batteries profoundly reflects the characteristics of current separator technology. It is reported that separators are a high value-added material with the highest technical barriers among lithium 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. Due to its technical complexity, the impact on power lithium batteries is even greater.

　　High-end separator technology for lithium batteries is a core threshold

　　Lithium battery separator technology is currently a pain point in my country's power battery industry. Among lithium-ion battery materials, positive and negative electrode materials and electrolytes are basically domestically produced, while separators started late, and the technological maturity of domestic companies is not high. Although the localization rate of my country's lithium battery separators has been increasing in recent years, 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. .

　　A common problem with domestic separators is low consistency, which is mainly manifested in irregular defects, substandard porosity, uneven thickness, pore distribution, and pore size distribution. High-end diaphragm technology has a very high threshold. Not only does it require huge investments, but it also requires a strong R&D and production team, sophisticated process technology and a high-level production line, and it takes a long time to achieve a breakthrough.

　　There is still a gap between China's basic material research on lithium batteries and the world's first-class level. In particular, high-end battery separator materials are still dependent on imports. From an industry perspective, the United States still leads the original innovation and core material research and development of lithium batteries; Japan, as a major battery material manufacturing country, has strict production standards and can be the first to manufacture new finished batteries; China and South Korea, as the second echelon, are following. Enter state. Compared with Japan and South Korea, China's low-end lithium battery products have more advantages, but there is still a big gap in some high-end products, especially in core materials and manufacturing processes related to battery safety.

　　In related fields in China, among the four core materials of lithium batteries, positive and negative electrode materials and electrolytes have been domestically produced, but the separator is still a shortcoming. China's domestic separators mainly supply the low-end 3C battery market, while high-end separators still rely heavily on imports. At present, the best lithium battery separator materials in the world come from two Japanese companies, Asahi Kasei and Toen Chemical, while 90% of China's domestic lithium battery aluminum plastic film market is also monopolized by Japanese manufacturers such as Showa Denko.

　　Domestic technology breakthrough for lithium battery separators

　　The new separator is a ceramic functional separator that uses substrate film surface treatment technology and inorganic ceramic powder dispersion technology to optimize the coating effect of ceramic powder and establish the relationship between coating thickness, ceramic type, particle size, surface characteristics, etc. and battery performance. The dose-effect relationship is summarized and the changing rules of technical parameters of ceramic diaphragms are summarized. The developed diaphragm has both current cutting characteristics and high heat resistance, and its technical indicators have reached the world's advanced level. Not only for ordinary lithium batteries, but also for single polymer lithium batteries, it can also meet the high consistency requirements. The heat shrinkage rate of a polyethylene separator coated with aluminum oxide with a thickness of 3 microns is less than 2% in 2 hours at 150°C. The performance is better than similar foreign products.

　　The AVIC lithium battery separator project has built a ceramic functional separator test line with an annual output of 3 million square meters. On this basis, it has completed the development of curing, slurry, coating, and slitting process technologies to form production capabilities, and carried out ceramic separator battery design, Trial production and testing play a vital role in improving the safety of lithium-ion power battery production and application. With the price of crude oil high and domestic air pollution due to exhaust emissions being serious, this is undoubtedly a positive energy for the promotion and use of new energy vehicles.

　　As the energy density of lithium-ion batteries increases year by year, the amount of inactive materials is getting smaller and smaller, and the separators are getting thinner, which will bring great challenges to the safety of lithium batteries. The production process of lithium battery separators is mainly divided into two directions: dry method and wet method. The product performance and cost efficiency of the two types of processes have their own advantages. The technology and process of dry separators have been continuously improved during long-term production: the stretching improvement technology ensures the stability of the stretching speed of the separator during low-temperature stretching and high-temperature stretching, and the heat treatment improvement technology makes the product more uniformly oriented in the same direction, forming The thickness and pore size distribution of the stretched film are more uniform.

　　Generally speaking: lithium batteries are representatives of modern high-performance batteries and are composed of four main parts: positive electrode material, negative electrode material, separator, and electrolyte. Among them, the separator is a film with a microporous structure and is the key inner component with the most technical barriers in the lithium-ion battery industry chain. my country's high-end separator technology for lithium batteries urgently needs a breakthrough.

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