Blog Post

Paraffin mix paves way for cooler electric car batteries

Electric vehicles may fast be moving from the future to the present, but there are still several elements that need to evolve before they become ubiquitous. The big one is the battery, which is thankfully attracting a lot of research. And while the development of better capacity and charging time tends to be the main focus, a new coolant called CryoSolplus looks to be a breakthrough result of a different kind.

CryoSolplus is made out of water, paraffin, surfactants and a touch of anti-freeze. It was developed by researchers at one of Germany’s Fraunhofer institutes, and it promises significant benefits over both air and water cooling.

Most importantly, the researchers say, it extends the life of electric car batteries. When these batteries can account for as much as half the cost of the vehicle, the importance of better coolants becomes obvious.

“The main problem we had to overcome during development was to make the dispersion [the coolant] stable,” said Tobias Kappels, a scientist at the Fraunhofer Institute for Environmental, Safety and Energy Technology.

At the moment, not all electric cars employ cooling, including those where the battery gets swapped out at service stations for charged replacements. But most of those that do tend to use air, which is not very good at absorbing and conducting heat, forcing engineers to leave large spaces between the battery’s cells to allow circulation. Water is better at dealing with heat, but requires a limited supply to be carried around in a tank.


According to the Fraunhofer scientists, the tank can be much smaller with CryoSolplus, as the substance is around three times better than water at absorbing heat. In other words, compared with both air and water, it’s a big space-saver.

The reason it’s better at absorbing heat is the use of paraffin: as the heat comes in, the paraffin droplets melt; as it leaves, the droplets solidify again. This is where the surfactants, or ‘stabilizing tensides’, come in — they stop the paraffin from collecting and clogging up the pipes.

CryoSolplus is still very much in development, so don’t expect it to be cooling your car’s battery just yet. The researchers are still optimizing its heat capacity, heat transfer and flow capabilities, and they’ve not actually conducted field tests in a car yet.

However, the Fraunhofer folks seem adamant that the substance will keep battery temperatures “within an acceptable range even in extreme driving situations.” As a summer drive can push today’s electric car batteries well over the 95 degree (35C) ‘comfort zone’ upper limit, that would mean much longer-lasting batteries than the ones found today.

And in turn, that may mean cheaper and greener electric cars.

One Response to “Paraffin mix paves way for cooler electric car batteries”