Synergistic Adsorption-Diffusion-Catalytic Effect Boosting Polysulfides Conversion by Rational Isotype Heterojunction Design for Highly Reversible Lithium–Sulfur Batteries

Sluggish reaction kinetics and ceaseless shuttle effect greatly restrict the actual performance of lithium–sulfur (Li–S) batteries. Herein, a rationally designed WO₃/SnO₂ isotype heterojunction is proposed as the surface modification on commercial separator to catalyze the redox conversion of the polysulfides. Experimental investigation, theoretical calculation, and in situ analysis cooperatively reveal that the “sesame ball”-like WO₃/SnO₂ spontaneously generates an internal electric field across the heterointerface, which offers moderate adsorption but rapid diffusion and accelerated conversion towards polysulfides. Meanwhile, the rich heterointerface acting as profitable nucleation sites guides the 3D growth of sulfide and thus impedes the inactivation of catalytic surface. As a consequence, the polysulfides shuttling is greatly restrained and highly reversible Li–S chemistry is constructed. Impressively, the unique heterojunction design endows a long-term cycling capability up to 1000 cycles at 2C, illustrating its highly efficient and long-lived catalysis capability.