Polycarbonate protects the heart of electric mobility

The automotive industry is in a state of upheaval worldwide. Alternative drive technologies, new forms of connectivity and autonomous driving necessitate completely new vehicle concepts. One of resin supplier Covestro's current focal points is how polycarbonate (PC) plastics can be applied in electric vehicles.

The heart of future electric cars and hybrid vehicles is a lithium-ion battery. 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 mm.

Covestro has many years of experience in encapsulating lithium-ion batteries for laptops and other electronic devices. To achieve this, the company has developed various polycarbonate blends that meet these requirements and are also extremely impact-resistant over a wide temperature range – especially at sub-zero temperatures. At the Fakuma 2018 trade fair, the company will present various battery modules, cell holders, crash absorbers and other products at its stand number 4206 in Hall B4.

“When it comes to cell holders and the integration of battery cells into modules, flame protection is particularly important,” explains Dr. Julian Marschewski from Covestro. 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.”

A flame-retardant polycarbonate ABS (acrylonitrile-butadiene-styrene) blend of the Bayblend FR type is ideal for cell holders and battery modules. It is temperature-resistant and dimensionally stable, and the parts can be produced efficiently with injection molding. The plastic is also used in mobile GreenPack rechargeable batteries from the Berlin-based manufacturer of the same name.

The crash absorber exhibited at Fakuma 2018 is made of the PC-PBT (polybutylene-terephthalate) Makroblend KU-2 7912/4. The material has very high impact strength and particularly high ductility at low temperatures. The honeycomb structure contributes to the extreme impact resistance of the crash absorber.

Another special material is the highly filled PC of the Makrolon TC product family, which are already used for heat sinks in LED lamps, for example. These products are thermally conductive but also available as electrically insulating versions so they can contribute to the efficient thermal management of batteries.

Off-road motorcycles typified by Enduros have to be ready for all wind and weather conditions, but above all must withstand the toughest mechanical demands. In these motorcycles, too, the trend is towards electric drive. Californian electric bike specialist Alta Motors is a leading manufacturer of such machines. The battery under the name Alta Pack is equipped with a jacket made of the extremely impact-resistant PC-PBT blend Makroblend.

Covestro continues to drive the safe integration of lithium-ion cells in the traction battery of electric vehicles forward. Next year, the company plans to actively participate in leading industry events such as the Battery Show from 5 to 7 May in Stuttgart and the Battery Experts Forum from 10 to 12 April in Frankfurt am Main.