​Evacuating the heat that builds up inside lithium-ion batteries during operation is crucial to preventing thermal runaway. To overcome the weaknesses of the plate-based cooling systems used in some electric vehicles (only one side of the plate cools, a thermal gradient is generated, and the cells age prematurely), Liten researchers are investigating a direct diphasic-fluid cooling system.

They built a demonstrator in which all of the cells in the battery pack are immersed in an insulating fluid circulated by a pump. The concept is not new, but the properties of the fluid are. In short, the fluid has a relatively low boiling point (around 65 °C). So, when the temperature exceeds the critical threshold, the fluid is vaporized at the hotspot, promoting substantial absorption of heat and, therefore, local and efficient cooling.  The phenomenon is passive, which, in theory, would ensure that heat continues to be extracted, even if the pump stops.

The system is currently being tested against existing systems in the lab for use in electric vehicles.