A new solid-state ceramic electrolyte could double the capacity of lithium batteries.
Researchers at the University of Michigan developed the technology to tackle issues with durability and short-circuiting in traditional lithium-ion batteries.
Battery technology for our smartphones and electric vehicles has remained largely unchanged since the 1990s, when lithium was combined with cobalt oxide to create electrodes that were safer, but less energy dense, than pure lithium-metal electrodes that had been trialled in the preceding decades.
The new solid-state electrolyte could enable a return to lithium-metal electrodes, and increase the capacity of batteries from around 600 watt-hours per litre to as high as 1,200 Wh/L.
"This could be a game-changer – a paradigm shift in how a battery operates," said Jeff Sakamoto, an associate professor of mechanical engineering at the university.
The ceramic layer sits on the surface of the electrode, preventing dendrites from forming and causing short-circuits and fires. "What we've come up with is a different approach – physically stabilising the lithium-metal surface with a ceramic," Sakamoto said. "It's not combustible. We make it at over 1,800 degrees Fahrenheit in air. And there's no liquid, which is what typically fuels the battery fires you see. You get rid of that fuel, you get rid of the combustion."
The breakthrough could also enable faster charging. Researchers used chemical and mechanical treatments to provide a pristine surface for lithium to plate evenly, suppressing dendrite formation.
“Up until now, the rates at which you could plate lithium would mean you'd have to charge a lithium-metal car battery over 20 to 50 hours (for full power),” Sakamoto said. “With this breakthrough, we demonstrated we can charge the battery in three hours or less. We're talking a factor of 10 increase in charging speed compared to previous reports for solid-state lithium-metal batteries. We're now on par with lithium-ion cells in terms of charging rates, but with additional benefits.”
Nathan Taylor, a postdoctoral fellow in mechanical engineering at the University of Michigan, said there was no visible degradation observed in the battery even after 22 days of testing. “The battery was just the same at the start as it was at the end. We didn't see any degradation. We aren't aware of any other bulk solid-state electrolyte performing this well for this long,” he said.
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