Freudenberg Sealing Technologies Develops Innovative Heat Shield to Make Batteries Safer

A company that is part of the Freudenberg group, Freudenberg Sealing Technologies, has developed an innovative heat shield that can be used to make batteries safer and thus makes electrified vehicles more viable in the long run. This heat shield can be used in prismatic and pouch cells with negligible impact when it comes to the space needed for installation. It comprises a silicone based elastomer that has a high heat resistance. When this is combined with the high insulating properties of air, the heat from a damaged cell remains insulated until it can be drained away.

As an outcome of this innovation, Freudenberg is now working on the achievement of greater range without increasing the size or weight of the battery. Greater energy output calls for higher safety requirements, and the shield is highly useful for the protection of the battery pack, especially in the event of thermal runaway where the temperatures in a cell could soar to 600 degree Celsius. In case the battery’s cooling system does not drain the heat away, this could lead to increase in temperature of neighboring healthy cells and trigger a chain reaction, ultimately causing an explosion.

The heat shield has three main characteristics. The shield itself is made of a heat-resistant material, a silicone-based elastomer. It has a waffle-like structure that slows the heat transfer between the cellsand comprises tiny pockets of air for outstanding heat insulation. The shield is also very thin, with the maximum thickness being just 1 mm. The loss of the existing energy density due to the shield’s use is hardly noticeable.

Freudenberg conducted a series of tests which showed a considerable reduction in temperature on the surface of the battery where the heat shields were placed. Freudenberg expert Peter Kritzer said, “This will adequately protect a neighboring cell against the destruction of cathode material or the separator.”

Freudenberg has also given great thought to the mounting of the heat shield. As the air pockets adhere well to the smooth metallic surface of a prismatic cell due to their suction effect, an individual shield can be positioned precisely.

If these flexible formations were extended over the top of the cell, it could enclose and seal the rupture disc located there. In case of overpressure in the battery cell, the ruptured disc would ensure that the resulting partially toxic gases escape in a controlled way. “Even more than energy density, safety is the most important characteristic of future battery generations in terms of quality,” Kritzer said.