By Josh Perry, Editor
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At the upcoming Fakuma 2018 trade fair for plastics processors in October, Covestro, one of the largest polymer companies in the world, will present new solutions for electric mobility in the automotive industry, including a polycarbonate housing for electric vehicle battery packs.

The Alta Pack battery of California-based electric bike specialist Alta Motors is equipped with a jacket made of the extremely impact-resistant PC-PBT blend Makroblend® from Covestro. (Covestro)

“When it comes to cell holders and the integration of battery cells into modules, flame protection is particularly important,” Dr. Julian Marschewski of Covestro explained in a press release. The electric mobility expert adds: “The properties of the materials used in the battery environment play a decisive role in passing the many functional and safety tests on the finished component and contribute to the battery's safe operation over its entire life cycle." 

Covestro has created a battery housing from a flame-retardant blend of polycarbonate ABS (acrylonitrile-butadiene-styrene), which is temperature-resistant and can be produced through injection molding. A plastic crash absorber is made from PC-PBT (polybutylene-terephthalate), which has a high impact strength and high ductility at low temperatures.  A thermally-conductive plastic that is also used for LED lamps can add to the thermal management of batteries.

The company highlighted a battery pack that it made for California-based Alta Motors on one its off-road, electric bikes.

Covestro noted, “In order to position a large number of battery cells precisely and in a small space, cell holders and frames as well as housing components must be very dimensionally stable and mechanically robust. Depending on the design principle of the battery pack, the material must also be flame-retardant and meet category V-0 of Underwriters Laboratories' UL94 flammability classification even at low wall thicknesses down to 0.75 millimeters.”

The battery pack is one of several automotive solutions that Covestro will be showcasing at the trade fair. There is also a polycarbonate front module that can be designed to individual specifications and offers a variety of functional integrations.

In addition, Covestro has partnered with Leister Technologies LLC to develop the process for laser-welding liquid-cooled battery modules for electric vehicles.

“Laser welding is traditionally only used with translucent or optically clear plastics,” a press release explained. “Covestro and Leister Technologies have extended use of this joining technique to include opaque flame-retardant Bayblend^®PC+ABS blend from Covestro, while achieving the same level of weld strength.”

The high impact strength of the plastic makes for a secure and leak-proof enclosure when laser welded. The material is also thermally-stable and has a good balance of high-heat distortion and physical performance.