Size control of sulfide-based solid electrolyte particles through liquid-phase synthesis

All-solid-state lithium-ion batteries (ASS-LiB) have garnered attention as the next-generation secondary batteries owing to their high safety and energy densities. The ASS-LiBs are composed of inorganic solid electrolytes, instead of an organic liquid electrolyte. Therefore, interstitial voids deteriorate the battery capacity, which is a serious problem with ASS-LiBs. A straightforward solution to this problem is to fill the voids using smaller particles. However, the particle size control is yet to be established, and there are insufficient studies on particle size control. In this study, nano-sized solid electrolyte particles of Li3PS4 (LPS), which is a typical sulfide solid electrolyte, was synthesized using a liquid-phase shaking method. The nucleation rate of LPS was improved using the submicron-sized Li2S as raw material, which was prepared through wet milling and dissolution-precipitation processes. Consequently, the liquid-phase shaking method with fine Li2S powder was successfully used to synthesize the nano-sized LPS particles with high ionic conductivity.