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A new lithium-based electrolyte invented by Stanford University scientists could pave the way for the next generation of battery-powered electric vehicles.

In a study published June 22 in Nature Energy, Stanford researchers demonstrate how their novel electrolyte design boosts the performance of lithium metal batteries, a promising technology for powering electric vehicles, laptops and other devices. "Most electric cars run on lithium-ion batteries, which are rapidly approaching their theoretical limit on energy density," said study co-author Yi Cui, professor of materials science and engineering and of photon science at the SLAC National Accelerator Laboratory. "Our study focused on lithium metal batteries, which are lighter than lithium-ion batteries and can potentially deliver more energy per unit weight and volume."

Lithium-ion batteries, used in everything from smartphones to electric cars, have two electrodes—a positively charged cathode containing lithium and a negatively charged anode usually made of graphite. An electrolyte solution allows lithium ions to shuttle back and forth between the anode and the cathode when the battery is used and when it recharges. A lithium metal battery can hold about twice as much electricity per kilogram as today's conventional lithium-ion battery. Lithium metal batteries do this by replacing the graphite anode with lithium metal, which can store significantly more energy.

"Lithium metal batteries are very promising for electric vehicles, where weight and volume are a big concern," said study co-author Zhenan Bao, the K.K. Lee Professor in the School of Engineering. "But during operation, the lithium metal anode reacts with the liquid electrolyte. This causes the growth of lithium microstructures called dendrites on the surface of the anode, which can cause the battery to catch fire and fail." Researchers have spent decades trying to address the dendrite problem.