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Immersion cooling for electric vehicles enables super-fast charging and improves range anxiety

Feature

By Mark Lashbrook, Technical Manager, M&I Materials

The electric vehicle (EV) revolution is well underway. In the UK and around Europe, deadlines are being set for last orders on internal combustion engine (ICE) vehicles, and companies with various visions are taking early steps in developing both EVs and charging infrastructure.

Yet progress is hampered by the same perennial thorns in the sector’s side, namely: charging speeds and range anxiety – the fear that the vehicle lacks sufficient charge to reach its destination.

Some argue that changing behaviour patterns is a solution, altering our relationship with cars. Yet, we shouldn’t be too quick to write off an engineering solution: As the EV sector hots up, immersion cooling can play a crucial role in reducing increasing charging speeds and improving range anxiety. Although these two are separate challenges, the solution for both could be the same.

Roadblocks to EV uptake

Buying a new car is a big purchase, normally accompanied by many questions: Which brand/model to choose? How many doors? Colour? Etc.

Today drivers have the additional option of choosing a fully electric vehicle, or a hybrid. This then further adds to the list of questions: How will I charge it? Where will I charge it? How often do I need to charge it? Some 64% of respondents to a recent JD Power survey are concerned about the lack of charging stations and 59% are concerned about range. Most respondents said they’re only willing to wait 30 minutes to charge their vehicle yet expect the charge to cover 200 miles.

In built-up urban areas, lack of off-street parking can make home-charging a bigger challenge, leaving potential buyers with no easy solution. Some might be able to charge at work; most hope a trip to a “fuel” station should do it. However, the lack of superfast charging can become a real problem. Right now, with ICE vehicles, filling up at a petrol station takes mere minutes – an experience that needs to be replicated for the EV market, too. In an ideal world, we should be able to pull up to a charging station, plug the vehicle in to charge whilst, say, we do some shopping or pick up a snack. This barrier to entry needs to be removed to ensure electric vehicles are widely adopted but are also the desired choice well before consumers are unable to purchase ICE vehicles.

So, what can be done? Unfortunately, it’s not as simple as installing more or faster charge points. Keeping batteries between 15-35°C keeps them working at optimum performance. When undertaking superfast charging, the power flows are greater, increasing heat in the batteries. To enable superfast charging, the batteries (and chargers) need to be effectively cooled to keep them within optimal range.

A chemical solution

Fortunately, it’s not all doom and gloom. Engineers have devised a solution to the range anxiety and superfast charging problem called “immersion cooling” – a thermal management method that keeps batteries and charge points cool. Batteries are kept cool by fully submerging them in liquid to disperse the heat, whereas charge points will use a cable to take away the high temperatures in a controlled loop. This has already been tried and tested in some sectors, including data centres, subsea cables and transformers.

Initially, immersion cooling was considered an early frontrunner for EVs, but since its chemical composition wasn’t right at the time and the fluid was too heavy, this approach fell behind. Keeping the weight of EVs down is crucial to their success, hence alternative cooling methods were pursued.

There are several ways to cool batteries: by air, plate or pipe, each with its own benefits and applications but none the best solution for superfast charging. Air cooling is typically used in mostly budget ranges of EVs and the vehicles are passively cooled, leading to slower charging speeds and increased battery wear.

Plate and pipe cooling offer a more sophisticated approach of extracting heat away from the battery. Refinements and efficiencies are being made in both these technologies which is why we can see faster charging and higher power output vehicles already. However, charging still typically takes between 30 and 40 minutes. The fastest charge speeds are only achieved in the first few minutes and then they are quickly reduced to protect the battery cells from overheating.

While these technologies can be developed and improved further, a step change in our thinking around cooling might be the key to solving the superfast charging challenge. That’s why immersion cooling deserves a second look. M&I Materials, which has a rich heritage in dielectric fluids, has developed a new chemical formula specifically designed for EV batteries – MIVOLT DF7. The improvement in cooling technology goes past range anxiety and superfast charging. At the most basic level, a better cooled battery is a better performing battery, meaning higher performance, increased range per single charge and longer cell life, all improving the EVs’ value proposition.

The road ahead

So, where could this technology take us? MIVOLT’s dielectric fluid in charging cables and car batteries promises fuelling cars similar to that of today, yet with a considerably reduced environmental impact. This is especially true when considering that MIVOLT is a fully biodegradable and non-toxic fluid that doesn’t hamper the recycling of batteries.

Historically, this isn’t the first mobility revolution humanity has gone through: Horses were swapped for cars and the necessary infrastructure built, with forecourts, car parks and mechanics garages to follow. Our current transition could be less revolutionary: forecourts will look very similar to those of today, with just as fast charging as fuel filling. Existing urban infrastructure can be upgraded with charge points without massive disruptions to the environment.

Tomorrow’s future could be closer to today than we think.

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