Stabilization of the Li3PS4’s High-Temperature Phase Achieved

Although most humans only relate room temperature with personal comfort, room temperature is significant for scientists attempting to develop specific material phases. 

Osaka Metropolitan University researchers have accomplished an unparalleled stabilization of the Li₃PS₄’s high-temperature phase—a crucial material for all-solid-state batteries—thereby achieving outstanding ionic conductivity at room temperature. This discovery gets people one step ahead in the realization of all-solid-state batteries and the implementation of this technology in a wide array of applications, along with electric vehicles.

All-solid-state batteries are predicted to be put to practical application as next-generation energy storage devices that combine high grades of safety and improved energy density, thus realizing a sustainable society. All-solid-state lithium batteries function by enabling the mobility of lithium ions via a solid electrolyte. Nevertheless, as ions could not mobilize freely within solids, developing solid electrolytes with high ion conductivity that, such as liquid electrolytes, facilitate the quick transfer of lithium ions, is imperative.

A study team headed by Professor Akitoshi Hayashi and Associate Professor Atsushi Sakuda of the Graduate School of Engineering at Osaka Metropolitan University was efficient in stabilizing the high-temperature phase of Li₃PS₄ (α-Li₃PS₄) for the first time. At room temperature, this shows high ion conductivity through quick heating to crystallize Li₃PS₄ at 400 °C min⁻¹. Because Li₃PS₄ is a potential solid electrolyte, this achievement has the potential to develop materials for all-solid-state batteries that exhibit greater performance.

Li₃PS₄ showcases varied crystal structures depending on temperature variations. The high-temperature phase is generally recognized for its superior ionic conductivity; however, the challenge has been to stabilize this phase at room temperature. We finally accomplished it by focusing on the heating rate during crystallization. This is the culmination of nearly 20 years dedicated to the development of all-solid-state battery materials.

Akitoshi Hayashi, Professor, Graduate School of Engineering, Osaka Metropolitan University

The research was published in Journal of the American Chemical Society.

Funding

This research was funded by the Japan Science and Technology Agency ALCA-SPRING project (grant number JPMJAL1301) and Japan Society for the Promotion of Science KAKENHI grants (grant numbers JP18H05255 and JP19H05816).

Journal Reference:

Kimura, T., et al. (2023). Stabilizing High-Temperature α-Li₃PS₄ by Rapidly Heating the Glass. Journal of the American Chemical Society. doi.org/10.1021/jacs.3c03827.