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 8 V vs. Li+/Li.