21700 battery

What is the current status of 21700 battery diaphragm technology?

21700 battery diaphragm technology is a pain point in my country's power 21700 battery industry. Among 21700 battery materials, positive and negative electrode materials and electrolytes have basically been domestically produced, while diaphragms started late and domestic companies have low technical maturity. Although the localization rate of 21700 battery diaphragms in my country has been increasing in recent years, it mainly occupies the low-end 3C battery diaphragm market, and the localization rate of high-end diaphragms is still very low. High-end 3C batteries and power 21700 battery diaphragms still rely heavily on imports.

It is reported that diaphragms are a high-value-added material with the highest technical barriers among lithium battery materials, accounting for about 15% of the cost of lithium-ion batteries. The technical difficulty lies in the engineering technology of pore making, matrix materials, and manufacturing equipment. The common problems of domestic lithium battery diaphragms are low consistency, mainly irregular defects, substandard porosity, uneven thickness, pore distribution, and pore size distribution. The porosity and pore size distribution of domestic PP diaphragms stretched in one direction are close to those of foreign products; the porosity of PE diaphragms stretched in two directions and in steps is usually lower than that of foreign products, and the pore size distribution is also not ideal.

In the field of wet-process diaphragms, domestic diaphragm companies are limited by many factors such as process and technology, and the product level is still low, and a large amount of processing equipment relies on imports. Like chips, high-end diaphragm technology has a very high threshold. It not only requires huge investment, but also requires a strong R&D and processing team, sophisticated process technology and high-level processing lines, and it is not possible to break through in a short time.

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