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Keeping EV batteries happy: A liquid solution

By 2040 the World Economic Forum expects the number of cars on the road to reach 2 billion – just under double the number in 2015. Electric vehicles will be critical in ensuring carbon targets are met in the face of this rising demand. Yet, while there are over 5 million electric vehicles on the road globally, the industry, still in its infancy, is yet to fully accomplish the challenge of addressing the key barriers to uptake: range anxiety and charging speeds.

Batteries Everywhere

Batteries are a bit like people, they like to be kept within a very narrow temperature range to be happy. Keeping batteries between 15-35°C keeps them working at optimum performance. When undertaking superfast charging the power flows are greater which increases heat in the batteries. In addition cold batteries cannot be charged quickly, so must be pre-heated.

To enable superfast charging, the batteries need to be effectively cooled, or heated, to keep them within the optimal range; there are a few methods already in use for thermal management – air cooling, plate cooling and pipe cooling. All come with their different benefits and applications, but none offer a sufficient solution to reach the higher charge rates desired by many would-be electric vehicle owners.

In a recent JD Power survey 59% of respondents said they are concerned about range, with more than 75% expecting electric vehicles to have a driving range of 300 miles or more. At present the average range in the UK is 202 miles.

Improving cooling technology goes past range anxiety and superfast charging. At the most basic level, a battery with good thermal management is a better performing battery. This means higher performance, more range on a single charge and a longer cell life, all increasing the value proposition for electric vehicles.

Thankfully, our engineers here at MIVOLT have devised a new solution to both the range anxiety and superfast charging problem – immersion cooling with ester liquids.

A Liquid Solution

Immersion cooling is a method of thermal management that can keep batteries and charging stations within their optimum temperature range. The former involves batteries being fully submerged in a special liquid which does not conduct electricity, also known as a dielectric, to control the temperature. The latter comprises the same liquid flowing from a charge point cable to a connector to keep it cool. This has already been tried and tested in other sectors, including data centres, subsea cables and transformers.

Immersion cooling was considered an early frontrunner for EVs. However, at the time the composition wasn’t right and the proposed fluid too heavy. Keeping the weight of EVs down is crucial to their success, so alternative cooling methods were pursued.

Yet with our rich heritage in dielectric fluids dating back some 40 years, we knew immersion cooling deserved a second look. Leveraging our in-depth expertise in developing innovative materials for the likes of Siemens, ABB and Boeing, we have developed a new chemical formula specifically designed for EV batteries – MIVOLT DF7.

The use of MIVOLT’s dielectric fluid in charging cables and car batteries will enable a future where the user experience of fuelling cars remains similar to today, but the environmental impact is considerably reduced. This is especially true when it’s considered that MIVOLT is a fully biodegradable and non-toxic fluid that doesn’t hamper the recycling of batteries, unlike the thermal pastes and other contact materials in plate or pipe cooling systems.

This isn’t the first mobility revolution we have gone through. Previously horses were swapped for cars and the necessary infrastructure delivered – forecourts built, car parks created and mechanics trained. This transition could be less revolutionary. The forecourts of the future could look very similar to the forecourts of today and car designs could remain virtually unchanged. With this innovation, tomorrow’s future could be closer to today than we think.

By Mark Lashbrook, Technical Manager