In-Situ Assembled VS 4 as a Polysulfide Mediator for High-Loading Lithium–Sulfur Batteries

A unique three-dimensional (3D) hybrid architecture configured with vanadium tetrasulfide (VS 4 ) nanomediators uniformly anchored in a reduced graphene oxide scaffold (VS 4 @RGO) is fabricated as a sulfur host via a facile in-situ assembly route. In the hybrid structure, the conductive, porous RGO skeleton functions as 3D electron channels and polysulfide reservoirs, effectively localizing the diffusing polysulfides. Meanwhile, the sulfiphilic VS 4 nanoparticles grown in situ in the 3D matrix act as a polysulfide mediator to offer sufficient polysulfide-anchoring and catalytic sites. The polysulfide adsorptivity and redox-conversion reversibility are substantially improved, as validated by first-principles calculations and in-situ XRD analysis. As a result, the Li–S cells achieve a low capacity-fading rate of 0.07% per cycle after 500 cycles. Furthermore, the assembled Li–S pouch cells with 200 mg of sulfur mass also deliver a high reversible discharge capacity of 730 mA h g –1 (146 mA h) after 50 cycles.