Lithium diaphragm industry in-depth report: core materials, bright prospects

Diaphragm is one of the core materials of lithium-ion battery. The performance of the diaphragm determines the interface structure of the battery, internal resistance, etc., which has an impact on the capacity and cycle of the battery. Diaphragm is mainly divided into dry and wet diaphragm, and the wet diaphragm accounts for more than 70%.

The diaphragm industry is a capital-intensive, technology-intensive and asset-intensive industry, with raw materials and manufacturing costs accounting for a large proportion of operating costs. Diaphragm base materials are mainly polypropylene (PP), polyethylene (PE) and other polyolefins, PE is the main raw material for wet diaphragm, PP is the main raw material for dry diaphragm, and there is a high dependence on raw material imports. The large proportion of manufacturing costs is mainly due to expensive production equipment, resulting in high equipment depreciation costs. Through the industry characteristics and diaphragm production cost analysis, we found that diaphragm companies mainly through the localization of raw materials and equipment, scale cost reduction, process improvement and other ways to reduce costs.

Coating integration has become mainstream, and major diaphragm factories have laid out coating production lines. The current lithium battery coating technology route for inorganic material coating, organic material coating, organic and inorganic material coating combination. Diaphragm coating to enhance the main direction of the two: high temperature, bonding; where high temperature is used most of the water-based ceramic (can withstand 150 degrees heat shrinkage), PVDF is mainly used as a bonding. Because PVDF is more expensive, the amount of larger, a large proportion of the cost of raw materials in the coating, PVDF localization will effectively reduce the cost of coating diaphragm.

No worries about demand, the global market share of domestic suppliers continues to increase. Total global demand for diaphragm is expected to reach 30.177 billion ㎡ in 2025, of which wet diaphragm, dry diaphragm is expected to account for 85%, 15%, the demand for 25.650, 4.527 billion ㎡ respectively.

Investment advice: diaphragm as an important lithium battery materials, the expansion cycle is long, production control is more important. Wet diaphragm has become a mainstream product in the field of power batteries, dry diaphragm in the field of energy storage also has a market, the demand side will maintain high growth. Suggest attention: Enjie shares, star source material, Sinoma Technology, Meilian New Material, etc.

Risk: downstream demand is not as expected; upstream raw material prices continue to rise sharply, industry cost reduction is not as expected; new technology development and application is not as expected.