Overcoming Challenges in Solid-State Sodium Battery Production

A novel process enables mass synthesis, resulting in a solid sulfide electrolyte with the world's highest reported sodium ion conductivity and a glass electrolyte with high formability.

Image Credit: Tridsanu Thopet/Shutterstock.com

Efficiency in rechargeable batteries is also necessary in the quest for greener energy storage. Since sodium is far more abundant than lithium, all-solid-state sodium batteries are gaining attention, even though lithium-ion batteries are currently the most widely used type of battery. The aim is to reduce the cost of sodium batteries, and while solid-state batteries are considered safer, challenges in processing have hindered mass production.

A research team led by Professor Akitoshi Hayashi of the Graduate School of Engineering and Associate Professor Atsushi Sakuda of Osaka Metropolitan University developed a process for the mass synthesis of sodium-containing sulfides.

The team produced a solid sulfide electrolyte with the highest reported sodium ion conductivity in the world—approximately ten times higher than needed for practical use—and a glass electrolyte with high reduction resistance. They used sodium polysulfides, or sulfides with two or more sulfur atoms, as the material and the flux, which encourages fusion.

Developing high-conductivity, formable electrolytes in large quantities is essential for successfully applying 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. 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.

Atsushi Sakuda, Associate Professor, Osaka Metropolitan University

Funding

Energy Storage Materials

The study was funded by JSPS KAKENHI.

Inorganic Chemistry

The research was funded by JSPS KAKENHI and the 2023 Osaka Metropolitan University (OMU) Strategic Research Promotion Project (Priority Research).

Advantages and Challenges in Solid-State Sodium Battery Production

Journal References:

Nasu, A., et al. (2024). Utilizing reactive polysulfides flux Na2S for the synthesis of sulfide solid electrolytes for all-solid-state sodium batteries. Energy Storage Materials. doi.org/10.1016/j.ensm.2024.103307.

Otono, T., et al. (2024). High-Sodium-Concentration Sodium Oxythioborosilicate Glass Synthesized via Ambient Pressure Method with Sodium Polysulfides. Inorganic Chemistry. doi.org/10.1021/acs.inorgchem.3c04101.