Automotive supplier tests immersion-cooled batteries for EVs

The two biggest challenges for electric cars—battery life and charge times—come down to battery cooling.

Now British auto parts supplier Ricardo is working with partners to come up with a new type of cooling technology that the company hopes will allow automakers to pack more energy into cars’ batteries and to charge them faster. The technology, called immersion cooling relies on coating the batteries with dielectric cooling gel, called MIVOLT, used as electrical insulation in other applications.

If it’s successful, the technology could prolong battery life in electric cars and accept higher current rates while charging without overheating them, and potentially bring charge times down closer to the time it takes to refill a gas tank. 

The i-CoBat immersion cooling project aims to reduce the size and cost of cooling systems to allow automakers to build denser battery packs without increasing the heat buildup. 

2019 Audi e-tron battery pack

2019 Audi e-tron battery pack

Today’s liquid cooling systems rely on cooling plates with pumps to circulate ethylene glycol or another coolant. If it proves effective, the immersive cooling technology could split the difference between those bulky, heavy systems and simpler air-cooled systems such as in the Nissan Leaf, which has been more prone to heat-related battery issues than other electric cars. 

Nissan, for instance, has limited the number of times the cars could fast-charge to prevent damage to the batteries, which made it difficult to take the cars on long trips that would require more than one or two DC fast charges, although the cars were equipped with CHAdeMO fast-charge ports. (Nissan has since issued a software update for the cars to allow them to use DC fast chargers more frequently.)

With simpler, cheaper cooling systems, electric cars could use bigger batteries that charge faster and last longer. The MiVOLT immersive coolant is also biodegradable, unlike ethylene glycol, which is also used as coolant in most gas engines. 

Nissan electric-car battery

Nissan electric-car battery

Ricardo is working on the project with British materials company M&I Materials and WMG, a manufacturing effort of the University of Warwick, in Britain as part of the British government’s Faraday Challenge.

The project isn’t the first to work on immersive cooling systems. A similar project launched in Taiwan in 2017.

“Power, performance, practicality such as fast charging times, and price are key determinants in persuading consumers to opt for an EV rather than a liquid-fueled vehicle when they next change their car,” said Neville Jackson, Ricardo’s Chief Technology and Innovation Officer.  “With current cell technologies, thermal management is a crucial enabler for improvements in these areas in order to reduce or eliminate range anxiety, and promote consumer acceptance of electric cars.”

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