A boost in battery chemistry could enable electric vehicles to run longer and charge faster, even in extremely cold temperatures. That improvement may prevent long lines at charging stations during the winter.
Both hot and very cold conditions can impact the performance of an electric vehicle鈥檚 lithium-ion battery, especially when the vehicle鈥檚 heating or air-conditioning system kicks in. This limits its driving range at extreme temperatures. A 2019 by the American Automobile Association found the average electric vehicle range dropped by 41 per cent at -7掳C (20掳F).
To improve lithium-ion battery performance, at Zhejiang University in China and his colleagues identified a promising new electrolyte 鈥� the battery component through which charged particles flow back and forth between the positive and negative electrodes.
Advertisement
鈥淓lectrolyte is probably the most important component inside a battery for enabling low temperature [operations] and fast charging,鈥� says at Virginia Tech.
Computer simulations and initial experiments suggest lithium ions might be able to flow faster through an electrolyte made from a solvent called fluoroacetonitrile (FAN). The new electrolyte enables greater battery capacity and faster charging, even at sub-zero temperatures. At a frigid -70掳C (-94掳F), a mere 24掳C above the coldest temperature on Earth, its conductivity was 10,000 times that of a standard battery electrolyte.
The researchers ran additional experiments to demonstrate how battery cells using the FAN-based electrolyte retained much of their room temperature capacity under extreme cold conditions. At -35掳C (-31掳F), the low end of the temperature range for an Alaskan winter, it held onto 76 per cent capacity; even at an Antarctic winter temperature of -80掳C (-112掳F), it maintained 51 per cent capacity.
Most commercial vehicles can experience freezing problems in extreme cold conditions regardless of whether they run on electric batteries or gas combustion engines, says at the University of California, Davis. But when it comes to electric vehicle batteries, 鈥渁ny new chemistry or technology has a much better chance to be adopted if it works in [a] wider temperature range鈥�, he says.
The experiments so far suggest a lithium-ion battery based on the new electrolyte could operate within a temperature range between a glacial -80掳C and a scorching 60掳C (140掳F), says Fan. In comparison, current commercial batteries typically work between -20掳C (-4掳F) and 55掳C (131掳F).
Despite the 鈥渆xtremely promising鈥� study, new batteries based on this improved chemistry will not be arriving any time soon, says at the Massachusetts Institute of Technology. He observed how changing out the electrolyte chemistry for batteries is 鈥渁 big commercial commitment鈥�. He also pointed to the need for additional testing to ensure any battery built around the new electrolyte would be safe and function well under real-world conditions.
The cost of fluoroacetonitrile compared to the common battery electrolyte is also steep: about $40 versus $0.05 per gram, says G贸mez-Bombarelli.
Fan and his colleagues also described the high cost of the new electrolyte as 鈥渢he major limiting factor鈥� for commercialisation. They plan to work on improving the electrolyte synthesis process to bring down its price while developing additives to further boost its performance.
Nature
