Battery Breakthrough for Electric Cars

Long-lasting, quick-charging batteries are essential to the expansion of the electric vehicle market, but today's lithium-ion batteries fall short of what's needed - they're too heavy, too expensive and take too long to charge. "A lithium-metal battery is considered the holy grail for battery chemistry because of its high capacity and energy density," said Xin Li, associate professor of materials science at the Harvard John A. Paulson School of Engineering and Applied Science. This battery technology could increase the lifetime of electric vehicles to that of the gasoline cars - 10 to 15 years - without the need to replace the battery. "Our research shows that the solid-state battery could be fundamentally different from the commercial liquid electrolyte lithium-ion battery," said Li. "By studying their fundamental thermodynamics, we can unlock superior performance and harness their abundant opportunities." Lithium batteries move lithium ions from the cathode to the anode during charging. "Our strategy of incorporating instability in order to stabilize the battery feels counterintuitive but just like an anchor can guide and control a screw going into a wall, so too can our multilayer design guide and control the growth of dendrites," said Luhan Ye, co-author of the paper and graduate student at SEAS. "The difference is that our anchor quickly becomes too tight for the dendrite to drill through, so the dendrite growth is stopped," Li added. "This proof-of-concept design shows that lithium-metal solid-state batteries could be competitive with commercial lithium-ion batteries," said Li. "And the flexibility and versatility of our multilayer design makes it potentially compatible with mass production procedures in the battery industry. Scaling it up to the commercial battery won't be easy and there are still some practical challenges, but we believe they will be overcome."