2D MoWS2 Alloy As Multifunctional Electrocatalyst for High Performance Cathode in Li-S Batteries

Abstract

The lithium sulfur (Li-S) battery is an energy storage device beyond Li-ion batteries which presents unique polysulfide chemistry resulting in high theoretical capacity of 2,600 Wh/kg. However, the unwanted shuttling of soluble lithium polysulfides (LiPSs) such as Li2S8 and Li2S6, corrodes the Li anode by forming an inactive sulfide layer and limit the life cycle of the Li-S battery. In previous studies, pristine 2D materials were used as the catalyst to anchor the polysulfides in cathodes and prevent the shuttling effect. The weight loading and concentration of catalysts in cathode was too high for the practical application in Li-S battery. In our study, we synthesized novel lightweight 2D Mo0.5W0.5S2 catalyst on CNT paper as a sulfur host cathode to efficiently catalyze the polysulfide reactions. Our catalyst shows mixed 2H-1T phase resulting in enhanced polysulfide binding, conversion and electron transfer resulting in improved specific capacity of 1,228 mAh/g at 0.1 C. The accelerated transformation of the dissolved polysulfides to the insoluble LiPSs resulted in an improved cyclic stability upto 400 cycles, as compared to 100 cycles for pristine cathode. Our study shows novel approach with binder-free ultra-light weight catalytic cathodes for practical application of Li-S battery.