EV battery coolant offers better temperature buffering

By using solid paraffin droplets, the team at the Fraunhofer Institute created a phase change material (PCM) that should last the life of the battery without the need to be changed.

‘The battery is the most expensive part of an electric vehicle, and so you do not want to be changing the battery so often. But to have a long life, it has be cooled effectively,’ said project lead Tobias Kappels of the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT in Oberhausen.

Indeed, for a typical lithium-ion battery, the optimum range lies between 20°C and 35°C — which can be exceeded in summer heat even with modest driving.

Current EV batteries are generally air-cooled; however, air is a poor conductor of heat and also requires large spaces between the battery’s cells to allow sufficient circulation.

Water-cooling systems are still in their infancy. Although their thermal capacity exceeds that of air-cooling systems, the downside is the limited supply of water in the system compared with the essentially limitless amount of air that can flow through a battery.