Cooling EV batteries

Name one enemy that can damage the batteries of electric vehicles: Heat.

A battery's comfort zone lies between 20°C and 35°C. If batteries are meant to have a long service life, overheating must be avoided. According to Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT in Oberhausen, Germany, operating a battery at a temperature of 45°C instead of 35°C halves its service time.

Fraunhofer researchers claimed they have developed a coolant for EV batteries that can absorb three times as much heat as water, and can prevent batteries from overheating.


Dubbed CryoSolplus, the coolant is a chemical dispersion that combines water and paraffin along with stabilizing tensides and a dash of the anti-freeze agent glycol.

As CryoSolplus absorbs heat, researchers said the solid paraffin droplets within it melt, storing the heat in the process. When the solution cools, the droplets revert to their solid form.

"The main problem we had to overcome during development was to make the dispersion stable,” stated Tobias Kappels, a scientist at UMSICHT. The individual solid droplets of paraffin had to be prevented from agglomerating or collecting on the surface of the dispersion. They had to be evenly distributed throughout the water.

Tensides serve to stabilize the dispersion, depositing themselves on the paraffin droplets and forming a type of protective coating. To identify which tensides were suitable, Kappels said they studied the dispersion in three different stress situations: How long can it be stored without deteriorating? How well does it withstand mechanical stresses such as being pumped through pipes? And how stable is it when exposed to thermal stresses, for instance when the paraffin particles freeze and then thaw again?

Research said the next step consists in carrying out field tests and trying out the coolant in an experimental vehicle.
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