Say goodbye to ‘range anxiety’: Thermal cloak for electric cars makes batteries last longer

For many EV drivers, the biggest fear on the road is the fear of running out of battery.

But the days of frantically searching for a charging station could soon be a thing of the past, thanks to a new thermal jacket that promises to make batteries last longer.

The brainchild of researchers at Shanghai Jiao Tong University, the cloak is designed to keep electric cars cool in the summer and warm in the winter.

Best of all, the mantle can do this passively, without the need for outside energy.

“The thermal cloak is like clothing for vehicles, buildings, spacecraft or even alien habitats to keep cool in summer and warm in winter,” said Dr. Kehang Cui, senior author of the study.

The brainchild of researchers at Shanghai Jiao Tong University, the cloak is designed to keep electric cars cool in the summer and warm in the winter

It is a known fact that electric vehicles (EVs) do not like colder conditions and they can limit performance.

This is because batteries work less efficiently when the temperature drops to single and minus digits.

The lithium-ion batteries in most modern EVs rely on a chemical reaction to store and release electricity, but when it’s colder, the process slows down and limits battery performance.

This results in the dramatic loss in usable range.

As explained by public charging operator Osprey, EV batteries have an optimum temperature of around 20°C to 25°C.

Charging when it is much colder or warmer than this will affect the chemical reaction and transfer of energy in the battery.

This means that the battery can take longer to charge, especially at night.

To counter this problem, the researchers designed a thermal mantle that can dampen natural temperature fluctuations.

Also called the Janus Thermal Cloak, the cloak has two main components: an outer layer that reflects sunlight and an inner layer that helps retain heat inside.

Called the Janus Thermal Cloak, the cloak has two main components: an outer layer that reflects sunlight and an inner layer that helps retain heat inside

The outer layer is made of thin fibers of silica covered with flakes of hexagonal boron nitride, a ceramic material similar to graphic. These fibers are braided and woven together into a fabric before being attached to the aluminum alloy inner layer

The outer layer is made of thin fibers of silica covered with flakes of hexagonal boron nitride, a ceramic material similar to graphic.

These fibers are braided and woven together into a fabric before being attached to the aluminum alloy inner layer.

To assess how effective the thermal cloak is, the team tested electric vehicles parked outside in Shanghai.

First, they tested the temperature of an uncovered car and found that the cabin had been reached 50.5°C in the afternoon.

However, when electric cars were covered with the thermal jacket, their interior was 22.8°C – 27.7°C lower.

Meanwhile, at midnight, the covered cars never dropped below 0°C – 6.8°C higher than the outside temperature.

“This is the first time we have been able to warm up almost 7°C above ambient temperature during winter nights,” said Dr Cui.

“This is also a bit surprising to us – there’s no energy supply or sunshine and we can still warm up.”

The team says the thermal jacket was purposely designed to make it easier to scale production in the future.

However, it remains unclear how much the cloak will cost, or when it will be available.

Speaking to MailOnline, Dr Cui said: ‘We have no estimate of how much the cloak would cost.

“We are conducting further larger-scale field testing and analysis to translate the metrics and performance of the thermal jacket we tested in our paper into real-world economic benefits, such as what percentage of battery life can we extend , or how much electricity and energy can we save annually if we apply the thermal jacket to a building.

“We hope to bring the thermal jacket to market soon.”

Why don’t electric cars like the cold?

Falling temperatures not only reduce an EV’s range, but also how fast the batteries charge – we explain why

It’s a known fact that EVs don’t like colder conditions and these can limit performance.

This is because batteries work less efficiently when the temperature drops to single and minus digits.

The lithium-ion batteries in most modern EVs rely on a chemical reaction to store and release electricity, but when it’s colder, the process slows down and limits battery performance.

Manufacturers have attempted to address this problem by equipping their latest models with auxiliary heat pumps to bring batteries up to operating temperature more quickly.

As the addition of a heat pump should reduce the impact of loss of range in winter, EV buyers are advised to purchase models that have them as standard or that can be fitted as an option.

And colder temperatures not only limit the range of batteries in electric cars, but also the speed at which they can be charged.

As explained by public charging operator Osprey, EV batteries have an optimum temperature of around 20 to 25 degrees – this is the window they operate in for ideal efficiency.

Charging when it is much colder affects the chemical reaction and energy transfer in the battery. This means that it can take longer to recharge the battery, especially at night when winter temperatures drop below zero.