New coating that allows OEMs to use composite battery cases for EVs, HEVs

The Zircotec Group, the UK-based specialist heat management company, has developed a new conductive ceramic coating that enables vehicle manufacturers to use carbon or plastic composite battery casings for hybrid and electric vehicles.

The coating overcomes composite’s inability to isolate the battery from electromagnetic fields and radio frequency interference (RFI), which has traditionally prevented the adoption of the material in this application.  It removes the need for traditional heavy metal casings, enabling a significant reduction in vehicle weight.

“The performance of power management systems and sophisticated electronics can often be corrupted, or degraded entirely, because of the level of interference produced in electric and hybrid vehicles,” said Simon Hiiemae, Zircotec Group technical director. “The commonly used metal battery case acts as a Faraday cage to absorb interference, either from the battery itself or surrounding sources, but the drive for efficiency and weight reduction has demanded a new approach. Composites simply don’t offer the same level of interference protection, which has limited the use of the material.”

The Zircotec coating is comprised of two layers; a metallic bond coat which provides the conductivity and a top ceramic layer which protects the metallic material from corrosion and wear. The chemistry of the coating can be optimised for any specific application. A thermal barrier layer can also be incorporated, by modifying the composition of the ceramic, to protect the battery from any nearby heat sources.

Traditionally, conductive foils or inks have been used to provide protection from interference, but they are easily damaged, limiting their effectiveness, while adding weight. The Zircotec solution is much lighter and more robust, guaranteeing continuous conductivity across the entire casing where the coating is applied. The coatings have also been proven to significantly improve the durability of composites by protecting them from nearby heat sources.

“The use of thermal sprays for RFI shielding has been used for many years in electronics,” says Hiiemae. “It is a tried-and-tested solution. Zircotec has now successfully developed a way of applying the coating to composite materials, allowing industries to use these materials in new and innovative ways.”

The new conductive ceramic coating is now available and is currently being trialled by a selection of vehicle manufacturers. The technology has also been developed for multiple industries, including rail, where overhead electrical equipment creates particularly challenging RFI situations.

“The battery system is one of the heaviest components of an electric vehicle, so reducing its weight is a key focus for vehicle manufacturers,” said Hiiemae. “By using a composite battery casing with our coating, they could save up to 4kg per square metre, compared to aluminium. A lot of our work now is helping customers overcome the inherent drawbacks of specific lightweight materials to enable them to be used in new areas.”