Wacker has announced a new silicone rubber, Elastosil R 531/60, which reliably insulates busbars in high-voltage batteries of electric cars. It will debut the solution at the forthcoming K 2025 International Trade Fair for Plastics and Rubber in Düsseldorf, Germany, this October.
Electric vehicle battery voltages are increasingly reaching 800V and beyond, with some approaching 915V. Higher voltages enable more power, shorter charging times and longer ranges, but also place greater demands on wiring and the insulation of electrical components. This is especially true for traction battery busbars — aluminum or copper rails that distribute current between battery cells and modules. With nominal voltages now commonly between 300V and 900V, ensuring reliable insulation of these components is essential.
Wacker’s silicone rubber has been designed to address these demands as it is flame-resistant and reliably prevents leakage currents and energy losses. The insulation remains intact at operating temperatures of up to 205°C. In the event of a fire, the cured rubber forms a solid ceramic material that sheaths the busbar and continues to insulate it electrically, thus reliably preventing short circuits. This protective layer remains intact even at temperatures between 800°C and 1,000°C.
With a hardness of 60 Shore A, the rubber can be applied to a busbar by extrusion, enabling cost-effective processing. The high flexibility and tear strength of the silicone enables busbars to be bent and adapted to the surface structures of the battery without cracking. No fractures or cracks occur even after impact tests. The material is said to be able to withstand temperature fluctuations and can withstand temperature fluctuations down to 40°C.
In related news, the forthcoming 2026 BMW iX3 50 xDrive has been developed with a focus on reducing the product’s environmental footprint that, the auto maker says, demonstrates the group’s “take on implementing a holistic approach to product sustainability across the entire lifecycle”. Read the full story here
