Analyze the development trend of lithium battery separators

by:CTECHi     2021-08-15

As one of the four key main materials of lithium-ion batteries, diaphragms are mainly divided into two categories: composite membranes and microporous membranes. Its performance has certain effects on the internal resistance, capacity, cycle performance and safety performance of the battery. As a material with the highest technical content and localization, the development of domestic diaphragms plays a vital role in the development of my country's lithium battery industry. On October 27-28, the '2017 (Ma'anshan) New Energy Vehicle Power Battery Intelligent Manufacturing Forum and Anhui Ma'anshan Power Battery Project Exchange Conference' hosted by the Maanshan Municipal Government of Anhui Province, starting point research, and lithium battery big data was held in Ma'anshan. Guo Buyang, deputy general manager of Donghang Optoelectronics, gave a keynote speech on the analysis of the power lithium battery separator industry at the conference. Market analysis predicts that my country's lithium battery production capacity in 2017 will be about 50GWH. Based on the above capacity, the demand for diaphragms is about 1 billion square meters. There is still a shortage of high-end diaphragm production capacity. At present, two major diaphragm companies in China have begun to use dry-process single-pull diaphragms in large quantities. , It is expected that there will be a shortage of dry-process single-pull diaphragm production capacity in the near future; dry-process 14+2 has been mass-produced, replacing wet-process 12+4 diaphragms in power batteries. The current production capacity of Donghang Optoelectronics diaphragm is 80 million square meters per year, and the designed production capacity is 150 million square meters per year. It will work closely with South China Normal University to add a new production base in Nantong, Jiangsu; the first phase of the new plant will add 6 base film lines and 10 coating lines. Multiple lines, 10 base film lines. The main indicators of the diaphragm include thickness, porosity, air permeability, heat shrinkage, puncture and tensile strength and appearance. The details are shown below:

Data source: China Eastern Optoelectronics Diaphragm Comparative Analysis Diaphragm preparation methods are divided into dry and wet methods. 1. Advantages of dry diaphragm: ①Uniform pore diameter and lower cost ②Good ionic conductivity ③Multilayer composite structure ④There is almost no heat shrinkage in the transverse direction. Disadvantages: low transverse tensile strength. Comparative analysis of the characteristics of dry and wet membranes:

Data source: Donghang Optoelectronics 2. Application of coated diaphragm Coated diaphragm mainly includes ceramic coating film and PVDF coating film. At present, dry-process diaphragms are basically applied to power batteries in the form of coating diaphragms; the more common models are 14+2; 16+4; 20+4. Compared with ordinary diaphragms, ceramic diaphragms have the following advantages: a. High thermal stability and low thermal shrinkage; b. High wettability with electrolyte c. Improved puncture resistance strength and battery safety, but coated diaphragms also have The major technical difficulties are thickness, compatibility, compactness, process temperature, matching and basic materials, as shown in the figure below:

Development trend of lithium battery separator In the future, the development trend of lithium battery separators will be diversified with the development of new fields such as power lithium batteries and energy storage. Simple polyethylene separators can only be applied to 3C products. The high-end market needs 'perfect separators' to support, coating, non-woven The technology of cloth and the combination of the two will be the future development direction.

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