Enhanced ionic conductivity of sulfide-based solid electrolyte by incorporating lanthanum sulfide

Solid electrolyte is the key point for developing all-solid-state lithium-ion battery with good recyclability and no safety problem. Here, a crystalline phase of lanthanum sulfide (La2S3) was incorporated into glassy sulfide-based solid electrolytes (Li2S–SiS2 or Li2S–P2S5) to form two composite systems Li2S–SiS2–xLa2S3 and Li2S–P2S5–yLa2S3. The results demonstrated that La2S3 has the ability to suppress the crystallization of Li2S–SiS2 or Li2S–P2S5 during the synthetic process. The lithium-ion conductivities of the designed composites can be improved by more than one order of magnitude in comparison with the pristine samples. And both of these two composites have a wide electrochemical window of more than 8V vs. Li+/Li.