Electrocatalysis in Lithium Sulfur Batteries under Lean Electrolyte Conditions

Abstract

The presence of electrocatalysis in lithium-sulfur batteries has been proposed but not yet sufficiently verified. In this study, molybdenum phosphide (MoP) nanoparticles are shown to play a definitive electrocatalytic role for the sulfur cathode working under lean electrolyte conditions featuring a low electrolyte/active material ratio: the overpotentials for the charging and discharging reactions are greatly decreased. As a result, sulfur electrodes containing MoP nanoparticles show faster kinetics and more reversible conversion of sulfur species, leading to improvements in charging/discharging voltage profiles, capacity, rate performance, and cycling stability. Taking advantage of the electrocatalytic properties of MoP, high-performance sulfur electrodes were successfully realized that are steadily cyclable at a high areal capacity of 5.0 mAh cm^-2 with a challenging electrolyte/sulfur (E/S) ratio of 4 μL_E mg^-1 _S .