Freudenberg unveils PFAS-free elastomer seal for EV batteries

Weinheim, Germany – Freudenberg Sealing Technologies (FST) has developed a new PFAS-free elastomer sealing material for electric vehicle (EV) battery cells, positioning it as ‘a high-performance alternative’ to conventional thermoplastic and FKM seals.

The newly designed material can be processed by injection moulding and is engineered to enhance sealing performance, extend battery life, and comply with tightening environmental regulations, FST said 10 April.

The product, it noted, meets the growing demand by OEMs in Europe and North America to comply with stricter national and international environmental standards.

According to FST, traditional thermoplastics seals are prone to deformation over time, especially under the repeated expansion and contraction cycles of battery cells during charging and discharging.

“Elastomers, by contrast, have a cross-linked molecular structure that enables them to retain their shape under stress," said David Kuhne, application engineer at FST.

This feature makes the elastomer seals "significantly more resilient in dynamic battery environments,” Kuhne added. 

“Battery cells are not rigid structures—they ‘breathe’ as they heat and cool. Our new elastomer O-rings prevent electrolyte leaks and block contaminants far more effectively than thermoplastics,” he added.

According to FST, the new sealing material also addresses critical battery longevity concerns.

Traditional elastomers used in battery applications have been linked to premature capacity loss due to material impurities and moisture infiltration.

When used in customer projects, the new material was able to improve the performance-relevant leakage rate of the battery cells by tenfold compared to conventional thermoplastic seals.

Another essential aspect is the 'extreme sensitivity' of battery cell electrochemistry to potential contamination.

“Premature capacity loss, which has been observed in cells sealed with conventional elastomers, can result from minimal but still present impurities in the sealing material,” said Dr Stefan Schneider.

The infiltration of moisture into the cell has a similar effect, as it can cause the decomposition of electrolyte components, explained the FST head of material development at the O-Rings lead centre..

According to Schneider, these aspects were addressed with the development of the new material. 

FST said that it has optimised its manufacturing technology to produce the battery seals in large scale.