Tungsten Oxide/Zirconia As an Efficient Polysulfide Mediator for High-Performance Lithium−Sulfur Batteries

Abstract

In this study, an effective strategy is proposed to enhance the limitations associated with the use of a Li2S cathode in lithium−sulfur (Li−S) batteries. Tungsten oxide/zirconia (WO3/ZrO2) with a ratio of 3:7 is prepared and integrated into a 2D compacted Li2S−graphene matrix through pelletization. The newly developed composite material has a great potential as cathode material for Li−S batteries. In the composite cathode, presence of a metastable high-pressure Li2S phase enable the direct conversion of Li2S to S8 during the first activation process, the high electrical conductivity of graphene, and simultaneously the integrated tungsten oxide/zirconia particles act as a polysulfide mediator to obstruct the outflow of soluble polysulfide into the electrolyte solution. Hence, the composite cathode shows high interfacial stability and thus substantially extends the lifetime of the Li−S battery over 200 cycles at a high Li2S loading of 10 mg cm−2. The practical Li−S full battery fabricated by combining the composite cathode and graphite anode provides outstanding cycle retention over 1500 cycles. References Hwang, J.-Y.; Shin, S.; Yoon, C. S.; Sun, Y.-K. ACS Energy Lett., 2019, 4, 2787−2795. Lee, S.-K.; Lee, Y. J.; Sun, Y.-K. J. Power Sources, 2016, 323, 174−188. Agostini, M.; Hassoun, J.; Liu, J.; Jeong, M.; Nara, H.; Momma, T.; Osaka, T.; Sun, Y.-K.; Scrosati, B. ACS Appl. Mater. Interfaces, 2014, 6, 10924−10928.