The development status of high-end separator technology for lithium batteries. It is understood that in related fields in China, among the four core materials of lithium batteries, positive and negative electrode materials and electrolytes have been domesticated. However, separators are still a shortcoming, and high-end separators are still heavily dependent on imports. The quality of the separator directly affects battery capacity, charge and discharge cycle life, flame retardant and explosion-proof safety performance and other indicators. At present, the manufacturing process of lithium battery separators is mainly divided into wet method and dry method.

　　Development status of high-end separator technology for lithium batteries

　　It is reported that the separator is 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.

　　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. .

　　As we all know, in the structure of lithium batteries, the separator is one of the key inner components. It not only prevents the positive and negative electrodes from contacting, but also ensures the passage of electrolyte ions. Therefore, the quality of the separator will directly affect the capacity, cycle, safety performance and other characteristics of the battery. Excellent quality separators play an important role in improving the overall performance of the battery.

　　The separator is currently a high value-added material with the highest technical barriers among lithium battery materials, accounting for about 15% of the cost of lithium batteries. Its technical difficulties lie in the engineering technology of pore creation, matrix materials, and manufacturing equipment.

　　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. The porosity and pore size distribution of uniaxially stretched domestic PP separators are relatively close to foreign products; the porosity of bidirectional step-stretched PE separators is usually lower than that of foreign products, and the pore size distribution is not ideal. These problems are all potential risks for the industry to be "controlled by others". If they are not solved well, they may curb the healthy development of my country's lithium battery industry.

　　High-end lithium battery separator technology has a very high threshold. It not only requires a huge investment, but also requires a strong R&D and production team, skilled process technology and high-level production lines, and it will not be possible to break through in a short time. However, the YYW-US trade war and the ZTE and Huawei incidents have sounded the alarm for my country's manufacturing industry. For the entire power battery industry, it is urgent to break through high-end separator technology for lithium batteries as soon as possible.

　　If domestic diaphragm companies want to make greater achievements, they must "make up lessons" in three major areas involving materials, equipment and process control, including basic material surface treatment technology, adhesive formulation technology, and product stamping and stretching. In addition, in the diaphragm industry chain Upstream, core production equipment including domestic coating machines also need to catch up and achieve greater breakthroughs in localization as soon as possible.

　　The role of lithium battery separator

　　The separator is one of the key components of lithium batteries. The main material of the separator is porous polymer membrane, including polyethylene and polypropylene. Separators for lithium batteries have strict requirements on safety, permeability, porosity and thickness.

　　Inside a lithium battery, charged ions flow between the positive and negative electrodes to form an electric current. The separator is located between the positive and negative electrodes inside the battery, which not only prevents direct contact between the positive and negative electrodes, but also ensures the smooth passage of electrolyte ions. . The lithium battery electrolyte is like a river, lithium ions are like boats running on the river, the diaphragm is a dam built along the middle, and the diaphragm holes are like gates on the dam. Under normal circumstances, ions can freely shuttle to the positive and negative electrodes, completing The cycle of charge and discharge.

　　High-end separators generally come with ceramic materials. If the temperature of the electrolyte is too high and the material expands, the pores will close like a gate, cutting off ion exchange, thus preventing the lithium battery from catching fire and exploding due to excessive temperature.

　　The separator is a material with the highest technical barriers among lithium battery materials. Its technical difficulties lie in the engineering technology of pore creation, matrix materials, and manufacturing equipment. If the development of lithium batteries is to be independent of others, high-end materials such as separators cannot be avoided! High-end diaphragm technology has a very high threshold. It not only requires huge investment, but also requires a strong R&D and production team, sophisticated process technology and high-level production lines.

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