EV growth drives investment in lithium-ion battery separator film

Japan's Sumitomo Chemical has decided to more than double its production capacity for lithium-ion secondary battery separators marketed under the Pervio brand name. Pervio is Latin for penetrable.

Production at its Ohe Works in Niihama, Japan will be raised by approximately 30% next spring. In addition, a new plant for Pervio will be built in South Korea, scheduled to start commercial-scale production in 2017.

The company's Pervio film is based on a structure composed of aramid fiber and ceramic as a composite heat-resistant layer formed on a polyolefin substrate. Pervio is mainly utilized in electric vehicles through its use in Panasonic's cylindrical lithium-ion secondary batteries. Pervio has also been deployed in Tesla Motors' Model S luxury vehicle. A premium is placed on safety in electric vehicle application and Pervio's heat resistance is key in achieving this.

Other suppliers of battery separators include Asahi Kasei E-Materials, with its Hipore high-density polyethylene (HDPE) product for use in cellphones, where heat resistance is not as much of an issue. Brueckner also uses HDPE in its Evapore battery separator substrate but a ceramic coating is added to impart heat resistance.