A researcher inspects a piece of lithium metal in the Phoenix Memorial Laboratory building at the University of Michigan. Source: University of MichiganA researcher inspects a piece of lithium metal in the Phoenix Memorial Laboratory building at the University of Michigan. Source: University of MichiganThere are numerous research projects involved in finding a more stable battery that can be used to replace ubiquitous lithium-ion batteries in consumer and appliance applications as well as in energy storage and electric vehicles.

Currently in development are paper-based, biodegradable batteries, organic flow batteries, quantum batteries that could help power small electronic devices, high-voltage liquid metal flow batteries that could be used in wind or solar power generation, salt-based batteries for electric cars and solar cells, self-assembling 3D batteries for consumer devices and many more.

Now, the University of Michigan is working on a rechargeable battery technology that could double the output of lithium-ion cells extending the range of electric vehicles or the time between smartphone charges. These batteries would be as small as current batteries, meaning the technology could be used in current form factors.

Current lithium-ion batteries consist of graphite anodes, which absorb the lithium and prevent dendrites from forming, resulting in more stable batteries. But this comes at the cost of performance and still has the potential to heat to unsafe levels for humans and devices.

University of Michigan researchers created a battery with a ceramic layer that stabilizes the surface, keeping dendrites from forming and preventing fires. This allows batteries to harness the benefits of lithium metal without the danger of fires or degradation over time.

"What we've come up with is a different approach — physically stabilizing the lithium metal surface with a ceramic," said Jeff Sakamoto, a U-M associate professor of mechanical engineering. "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."

In previous solid-state electrolyte tests, lithium metal grew through the ceramic electrolyte at low charging rates, causing short circuits much like in liquid cells. Researchers found a way around this problem with chemical and mechanical treatments that provide a pristine surface for lithium to plate evenly, like suppressing the formation of dendrites or filaments. This improves safety but enables dramatic improvements in charging rates, Sakamoto said.

"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 3 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."

The full research will be published in the Aug. 31 issue of Journal of Power Sources.

To contact the author of this article, email pbrown@globalspec.com