Baypreg® STM for lightweight battery pack covers and underbody protection for EVs

Polyurethane composite solution for lightweight and fire resistant battery covers

Baypreg® STM is Covestro's innovative polyurethane system designed for high-performance EV battery covers and structural components in electric vehicles, offering a sustainable alternative to traditional materials.

The manufacturing process utilizes advanced Spray-Transfer-Molding technology, where robots precisely spray PU formulation onto glass fiber mats. These mats are then transferred into a compression mold where the composite part is formed and cures under controlled pressure and temperature conditions. 

The process delivers significant manufacturing advantages: short cycle time, high automation potential, efficient material usage, and the integration of flanges for mounting on the battery casing. Additional functional material layers and thin steel sheets can be integrated into the composite structure during the compression step, if required.

The final components outperform traditional solutions with up to 60% weight reduction compared to steel, while providing high mechanical properties and excellent flame retardancy to increase fire protection in case of a thermal event. Additional benefits include electrical insulation, a part smooth surface, gas impermeability and corrosion resistance - making Baypreg® STM ideal for modern EV applications.

EV battery underbody protection lightweight PU composite solution

For vehicle underbody protection, Baypreg® STM offers a unique sandwich design combining our proven Spray-Transfer-Molding technology with a rigid polyurethane foam core. The efficient process allows manufacturers to create strong, lightweight panels featuring acoustic properties, durability and impact resistance, protecting the battery pack against stone chipping and ground impact loads. The resulting components provide comprehensive vehicle protection with integrated functionality for modern mobility solutions.