Blanket for electric cars helps preserve battery performance

Draping an electric car with a temperature-regulating blanket while it is parked could help keep its battery in prime condition.

When an electric vehicle is parked outside, or in an unheated garage, its temperature can vary dramatically from day to night and from season to season, from well below freezing to well above 40°C (104°F), depending on where it is in the world.

But to stay in optimum condition, the lithium-ion batteries that power electric cars should be stored between 15°C (59°F) and 35°C (95°F). This range is also optimum for charging and discharging.

Most batteries have built in thermoregulation capabilities to keep them within a safe temperature range when in use, but this drains power that could otherwise be used for driving, and does nothing for stationary cars. So Kehang Cui at Shanghai Jiao Tong University, China, and his colleagues have developed a blanket that aims to regulate an electric car’s temperature, keeping its batteries at peak performance.

The blanket features an outer layer made from silica and boron nitride, which reflects heat and sunlight, while an inner layer made from aluminium traps heat to keep the car’s temperature constant. In tests, the team found it could cool an electric vehicle by 8°C (14°F) on a hot day, compared to the outside temperature, and warm it by 7°C (13°F) at night.

Cui says the blanket could be scaled up into commercial production to improve the performance and longevity of battery vehicles. But he says more research is needed to quantify the improvements it offers to battery performance, and the payback period for the technology, before drivers are likely to invest. “I think it’s a material that would benefit our daily life. But there’s lots of work to do,” he says.

It could also find use with domestic battery storage systems, energy storage power plants and even buildings, says Cui. “A sustainable energy system relies on energy storage, and energy storage requires thermal management – and then the blanket will be useful,” he says.