Better batteries for better electric vehicles

Electric vehicles promise to revolutionize transportation but they need safer, better-performing batteries. Now, a Faculty of Science researcher at the University of Calgary, and colleagues at the University of Maryland (UMD), College Park in the United States have made major inroads toward developing a next-generation, all solid-state lithium battery.

Venkataraman Thangadurai, professor in the Chemistry Department at the University of Calgary, worked with project leader Eric Wachsman, professor of engineering at UMD, and other scientists at UMD to build the advanced battery. They published their recent findings, “Negating interfacial impedance in garnet-based solid-state Li metal batteries,” in  Nature Materials.

Current lithium-ion batteries have several issues. They include leakage, poor chemical stability, flammability, and limited operating voltage or energy density. But the UCalgary-UMD research team’s new button-sized lithium battery is chemically stable, non-flammable and can operate safely at a higher voltage than existing batteries. “The technology we have developed would enable absolutely stable, robust, safe, high-powered, all solid-state lithium batteries for future energy storage,” Thangadurai says.

Existing lithium-ion batteries like those used in electric and plug-in hybrid vehicles, as well as in portable electronics, use membranes of organic polymer compounds and lithium salts as the electrolyte. The electrolyte in a battery separates the two electrodes (the positive cathode and the negative anode), and conducts the lithium ions between the electrodes during charging and discharging cycles. Currently used organic polymer-based electrolytes are flammable, so fire is a safety issue.

Wachsman and co-principle investigators Thangadurai and Liangbing Hu, along with other UMD scientists, instead used a solid ceramic electrolyte, which doesn’t burn. The research team also used, for the first time, a technique called atomic layer deposition to place a thin film of aluminum oxide on top of a garnet structure coating the ceramic electrolyte.

They showed there was “negligible interface resistance” between the lithium metal anode and the ceramic electrolyte interface, resulting in fast transport of charges and higher performance overall. Their newly developed interface chemistry also enabled the team to use a lithium metal anode and a high-voltage cathode, which will significantly boost their battery’s energy storage capacity and operating voltage compared with existing lithium-ion batteries.

Thangadurai pioneered the use of garnet-type ceramics in solid-state lithium batteries several years ago, while working as a post-doctoral researcher at the University of Kiel in Germany. About three years ago, he took a sabbatical research leave from the University of Calgary and pursued the technology with Wachsman and his team at the University of Maryland.

“That collaboration enabled us to invent the needed breakthrough in solid-state batteries that not only overcomes the inherent flammability issues with today’s batteries, but is resulting in the development of a truly revolutionary smaller, lighter, and lower-cost battery to meet the rapidly growing need for energy storage,” says Wachsman, director of UMD’s Energy Research Center.

Thangadurai expects it will take about five years to develop a commercial-scale, solid-state lithium battery incorporating their technology. The team’s international collaboration was supported by a contract with the U.S. Department of Energy.

This article was adapted with permission from  The University of Calgary.

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