Bi-functional material SnSSe/rGO with anionic vacancies serves as a polysulfide shuttling blocker and lithium dendrite inhibitor

Abstract

The notorious polysulfide shutting and the irregular lithium dendrites are the leading causes for hindering lithium-sulfur batteries’ marketization. Herein, a bi-functional material consisting of an anionic vacancy-rich SnSSe layer stacked with graphene (SnSSe/rGO) composite is proposed, which possesses the characteristics of simultaneously immobilizing polysulfides and suppressing dendritic growth. The enhanced sulfiphilicity enables SnSSe/rGO as a separator modification layer (SnSSe/rGO@PP) to effectively adsorb polysulfides and catalyze their rapid conversion. The Li-S half-cell containing SnSSe/rGO@PP exhibits long cycling stability and outstanding rate capacity. Moreover, SnSSe/rGO can regulate lithium deposition behavior due to its strong lithiophilicity and interaction with lithiated products. The lithium anode employing SnSSe/rGO electrode (SnSSe/rGO@Cu-Li) demonstrates low nucleation overpotential and stable plating/stripping cycling. Consequently, the prepared Li-S full cells demonstrate a remarkable area capacity of about 8.0 mAh cm−2, even when subjected to lean electrolyte (9.0 µL mg−1) and low N/P ratio (about 1.3) with high sulfur loading (11.2 mg). This study reveals a fresh perspective for designing efficient bi-functional materials to solve both the shuttle effect and lithium dendrites in high-energy-density Li-S batteries.