Yan Yao and Ye Zhang work with all-solid-state sodium batteries. (Image: uh.edu)

Currently the preferred technology to power electric vehicles, lithium-ion (Li-ion) batteries, has become too expensive for long-duration grid-scale energy storage systems — not to mention that lithium itself is becoming more and more elusive.

Li-ion batteries are preferred technology for a reason — high energy density and capacity to be combined with renewable energy sources to support grid-level energy storage — but lithium carbonate prices are at an all-time high. Supply-chain issues, the Russia-Ukraine war, and increased demand are all to blame for the high price.

New research published in Nature Communications and conducted at the University of Houston may have nipped the problem in the bud. The work eyes ambient-temperature, solid-state sodium-sulfur battery technology as a viable alternative to lithium-based battery technology for grid-level energy storage systems.

Cullen Professor of Electrical and Computer Engineering Yan Yao and his colleagues developed a homogeneous glassy electrolyte that enables reversible sodium plating and stripping at a greater current density than previously possible.

“The quest for new solid electrolytes for all-solid sodium batteries must concurrently be low cost, easily fabricated, and have incredible mechanical and chemical stability,” said Yao — also principal investigator of the Texas Center for Superconductivity at the University of Houston. “To date, no single sodium solid electrolyte has been able to achieve all four of these requirements at the same time.”

A novel form of oxysulfide glass electrolyte has the potential to satisfy all these requirements at the same time, the research shows. A high-energy ball milling process was used to create the electrolytes at room temperature.

“The oxysulfide glass has a distinct microstructure, resulting in a completely homogeneous glass structure,” said Ye Zhang, Yao’s research associate. “At the interface between sodium metal and the electrolyte, the solid electrolyte forms a self-passivating interphase that is essential for reversible plating and stripping of sodium.”

“Our study overturned this perception by establishing not only the highest critical current density among all Na-ion conducting sulfide-based solid electrolytes, but also enabling high-performance ambient-temperature sodium-sulfur batteries,” Yao said.

“The new structural and compositional design strategies presented in this work provide a new paradigm in the development of safe, low-cost, energy-dense, and long-lifetime solid-state sodium batteries,” Zhang said.



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This article first appeared in the September, 2022 issue of Battery & Electrification Technology Magazine.

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