Boosting Redox Kinetics of Sulfur Electrochemistry by Manipulating Interfacial Charge Redistribution and Multiple Spatial Confinement in Mott-Schottky Electrocatalysts

The serious shuttle effect and sluggish reaction kinetics intrinsically handicap the practical application of Li-S batteries. Herein, a unique 3D hierarchically porous Mott-Schottky electrocatalyst composed of W2C quantum dots (QD) spatially confined in nitrogen-doped graphene microspheres (NGM) is proposed for regulating the kinetics of sulfur electrochemistry. Experimental and theoretical results disclose a spontaneous charge rearrangement and induce built-in electric field across the W2C QD/NGM heterojunction interface, contributing to reduced energy barrier for both polysulfides reduction and Li2S oxidation during entitle discharge/charge processes. Furthermore, the ultrasmall W2C QD with high electrocatalytic activity and superior conductivity can promote the conversion of S species, while the hierarchically porous microspheres assembled from wrinkled graphene nanosheets not only can efficiently inhibit the polysulfides shuttling via multiple spatial confinement, but also provide abundant inner space for stable reservation of active S, highly conductive networks, and maintain the structural integrity of cathode during consecutive cycling. Consequently, Li-S batteries employed with the designed W2C QD/NGM-based cathode exhibit outstanding electrochemical properties even at a high sulfur loading. The superior performance combined with the simplicity of the synthesis process represents a promising strategy for the rational design of advanced electrocatalyst for energy applications.