Electrocatalysis in Lithium Sulfur Batteries under Lean Electrolyte Conditions

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.