Y2S3-Doped Li2S Active Cathode Materials for All-Solid-State Li-S Batteries

All-solid-state Li-S batterieswith sulfur-basedcathodeshave attracted attention, because of their high theoretical energydensity. However, it is difficult to transfer electrons and ions andactivate redox reaction of Li2S because Li(2)Sand S are insulators. In this study, the Y2S3 doping of Li2S active cathode materials was performedto enhance their properties while minimizing the dopant amount. Asa result, the 99Li(2)S-1Y(2)S(3) (mol %) active cathode material exhibited the highest reversiblecapacities of 953 mAh g(-1) that exceeded those ofintrinsic Li2S, although its Y2S3 content (1 mol % = 5.7 wt %) was lower than that reported in a previouswork. Transmission electron microscopy observations indicated thatY atoms aggregated on the Li2S surface in the form of P-dopedLiYS(2) species, and their morphology did not change afterthe charge-discharge process. This result indicated that theP-doped LiYS2 at the Li2S surface served asa catalyst. In addition, the full cell of the 99Li(2)S-1Y(2)S(3) (mol %) with Si anode shows high capacity of605 mAh g(-1). These findings of this study enablethe material design of Li2S-based cathode active materialsfor use in high-energy-density Li-S batteries.