All-Solid-State Sodium Batteries Near Practical Use

Osaka Metropolitan University

The pursuit of greener energy also requires efficient rechargeable batteries to store that energy. While lithium-ion batteries are currently the most widely used, all-solid-state sodium batteries are attracting attention as sodium is far more plentiful than lithium. This should make sodium batteries less expensive, and solid-state batteries are thought to be safer, but processing issues mean mass production has been difficult.

Osaka Metropolitan University Associate Professor Atsushi Sakuda and Professor Akitoshi Hayashi, both of the Graduate School of Engineering, led a research team in developing a process that can lead to mass synthesis for sodium-containing sulfides.

Using sodium polysulfides (sulfides with two or more atoms of sulfur) as both the material and the flux, which promotes fusion, the team created a solid sulfide electrolyte with the world's highest reported sodium ion conductivity—about 10 times higher than required for practical use—and a glass electrolyte with high reduction resistance.

Mass synthesis of such electrolytes with high conductivity and formability is key to the practical use of all-solid-state sodium batteries.

"This newly developed process is useful for the production of almost all sodium-containing sulfide materials, including solid electrolytes and electrode active materials," Professor Sakuda said. "Also, compared to conventional methods, this process makes it easier to obtain materials that display higher performance, so we believe it will become a mainstream process for the future development of materials for all-solid-state sodium batteries."

The results were published in Energy Storage Materials and Inorganic Chemistry.

About OMU

Established in Osaka as one of the largest public universities in Japan, Osaka Metropolitan University is committed to shaping the future of society through "Convergence of Knowledge" and the promotion of world-class research. For more research news, visit https://www.omu.ac.jp/en/

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