TECHNOLOGY

Blanket for electric cars helps preserve battery performance

             The lithium-ion batteries found in electric cars work best when kept within a certain temperature range, so researchers have created a blanket to keep your car cool in the sun and warm in the cold. 

             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.

          In the past five years, a revolution has gathered pace in the transport sector. Electric cars, once the sole preserve of those with deep pockets, have hit the mainstream.

              The latest figures released on 26 April by the International Energy Agency (IEA) suggest almost one-in-five new cars sold worldwide this year will be either full battery electric or plug-in hybrid models. In total, 14 million of these kind of vehicles are expected to be sold this year, up from around a million in 2017.  

            This explosive growth is testament to industry innovation and government interventions. Falling battery costs have delivered longer-range cars, boosting their consumer appeal. Meanwhile, government policies, including looming bans on the sale of new petrol and diesel cars in some countries, have nudged people to embrace zero-emission driving.  

          The result is a transformation in the car industry that will reshape the world’s energy use. Global oil demand for road transport will peak in 2025, the IEA predicts. “The internal combustion engine has gone unrivalled for over a century, but electric vehicles are changing the status quo,” said Fatih Birol at the IEA in a statement. 

             But although electrification of the global vehicle fleet brings climate benefits, there is also cause for concern. SUVs have been growing in popularity in recent years, accounting for 42 per cent of all car sales in 2020. In tandem, electric SUVs have also gained ground, representing roughly 35 per cent of electric passenger car sales in 2022. 

           Christian Brand at the University of Oxford dubs this trend towards larger cars a “mobesity” epidemic. Electric SUVs are still greener than their petrol and diesel counterparts, but their size and weight erases some of the climate gains from moving to electric vehicles (EVs). Their larger batteries also require more raw minerals, like cobalt and lithium, putting extra pressure on already stretched global supplies. “The trend towards larger cars is definitely not desirable at all,” says Brand.

             He suggests new policies to encourage people to opt for smaller EVs may be needed, such as hiking taxes for electric SUVs. “Of course, that’s unpopular with policy-makers because they would fear losing votes. But we could save hundreds of millions of tons of carbon over time, cumulatively, to 2050, if we did something like this in the UK,” he says. 

            Air pollution is another worry. In poorer countries like India, electric scooters and tuk-tuks are replacing diesel-powered vehicles in their droves, the IEA reports, which will lead to significant improvements in urban air quality. But in richer countries, where petrol and diesel cars tend to be cleaner, the situation isn’t so clear, says Frank Kelly at Imperial College London.

          “The benefit of moving to an electric vehicle, from an exhaust emission point of view, is actually pretty small,” says Kelly. And since electric vehicles still produce pollution from their tyres, brakes and road wear, air pollution won’t fully go away. “We’re still going to have a pretty big problem in our cities,” says Kelly. 

           As such, governments must do more to reduce car dependency, particularly in urban areas, says Kelly. “Clean public transport is the solution to our air pollution problem in urban areas,” he says. “And really, we should be minimising all private vehicles as much as possible, not celebrating the increased numbers.”