Strong Interfacial Adhesion between the Li₂S Cathode and a Functional Li₇P_2.9Ce_0.2S_10.9Cl_0.3 Solid-State Electrolyte...

The extrinsic cathode interface between the sulfide electrolyte and the Li₂S electrode is always ignored in all-solid-state lithium-sulfur batteries. However, the aggregation of the Li₂S cathode is still observed during cycling. The gradually lost extrinsic contact interface between the cathode and the electrolyte would result in considerable interface resistance and severe capacity decay in the cell due to the lack of efficient electron and ionic conduction at the interface. Herein, a facile dual-doping strategy demonstrates the synthesis of a functional inorganic electrolyte. The obtained Li₇P_2.9Ce_0.2S_10.9Cl_0.3 glass-ceramic electrolyte shows a higher-lithium-ionic conductivity of 3.2 mS cm^-1 at room temperature. Further, UV-vis absorption and ex situ scanning electron microscopy studies confirm robust interfacial adhesion between the functional inorganic electrolyte, Li₇P_2.9Ce_0.2S_10.9Cl_0.3, and the Li₂S cathode. Thus, a stable extrinsic cathode interface is unprecedently built. Finally, the all-solid-state lithium-sulfur battery based on the Li₇P_2.9Ce_0.2S_10.9Cl_0.3 electrolyte delivers a higher reversible initial capacity of 617 mA h g^-1, a lower interface resistance of 25 Ω cm² and much better cycling stability (with a high capacity retention of 89% after 100 cycles) than the pristine Li₇P₃S₁₁ electrolyte.