Excoriation-Type Catalyst-Solvent Interface with Dual Active Sites to Enhance Polysulfide Desolvation Kinetics for Lean-Electrolyte Lithium-Sulfur Batteries.

Humdrum catalyst-polysulfide interactions in sulfur cathodes of lithium-sulfur (Li-S) batteries show limited effectiveness to further accelerate the sluggish conversion reaction kinetics under lean electrolyte conditions. Herein, we design an electrode/electrolyte interface coupled with W2N nanoparticles and single-atom W (SA-W) on ultrathin carbon nanosheets for improving the conversion reaction kinetics of Li-S batteries from the perspective of accelerating the desolvation of lithium polysulfides (LiPSs). The desolvation kinetics near the electrode/electrolyte interface are enhanced by the excoriation-type effect of SA-W, first exfoliating the solvation sheath of LiPSs through d-2p hybridization, and then by W2N nanoparticles adsorbing LiPSs and catalyzing their reduction reaction. Structurally, these carbon nanosheets are self-assembled into hollow microspheres, which reinforce the spatial confinement effect and accommodate the volume change during lithiation/delithiation under high sulfur loading. Such optimized catalyst-reactant/-solvent interactions have elicited superb rate capability (with reversible capability of 702 mAh/g at 5C) and remarkable cycling stability (with capacity degradation rate as small as 0.05% per cycle at 1C over 600 cycles). Benefiting from the rapid desolvation process of LiPSs, a high areal capacity of 13.5 mAh/cm2 can be achieved even under high sulfur loading (11.4 mg/cm2) and low electrolyte/sulfur ratio (5 µL/mg). The proposed catalyst/solvent interface engineering has the potential to inspire sustainable liquid-solid interconversion electrochemical energy storage.