China is steadily positioning itself at the forefront of Li-on battery production. One sign of this is a massive ramp-up of the production of wet-process separators (separators are a critical component of Li-on batteries – they keep the anode and cathode from touching, while allowing ions to pass through).
Shanghai Energy has announced that it will be opening a huge new wet-process separator plant in Wuxi city, costing roughly $789 million. According to the company, this facility will make it the largest producer of wet-process separators in the world.
There are two primary methods for fabricating separators. The first is a dry process in which the separators are created from extruded sheets of polypropylene or polyethylene. The sheets are then annealed and rapidly stretched to attain the desired crystal structure and porosity. The Chinese company Shenzhen Senior Technology Material is estimated to have produced 120 million square meters of dry-process separators in 2016.
The second method for fabricating separators is a wet process, which involves extruding the polymer mixed with a plasticizer at high temperatures. The resulting porosity is around 40%-50%, which is higher than the porosity of separators produced using the dry process. The wet process also produces spherical or elliptical pores, rather than the slit pores of the dry process. In 2016, Shanghai Energy sold roughly 100 million square meters of wet-process separator material.
Despite today’s higher volume in dry-process separators, CCM, a Chinese marketing intelligence company, has predicted that Chinese production will see an overall shift to the wet process. The wet-process separators sold by Shanghai Energy have already gotten attention from customers such as LG, BYD, and CATL. Shanghai Energy’s current production output is roughly 320 million square meters per year.