Single-Atom Iron and Doped Sulfur Improve the Catalysis of Polysulfide Conversion for Obtaining High-Performance Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries are regarded as promising secondary energy storage devices for their high energy density and low cost. The electrochemical performance of Li–S batteries is mainly determined by the efficient and reversible conversion of lithium-polysulfides to Li2S when discharging and to S when charging. Herein, a catalytic strategy is proposed to accelerate the reversible conversion of S and the discharge products in Li–S batteries. This reversible transformation is achieved with active sites of single-atom iron on nitrogen- and sulfur-doped porous carbon (FeNSC). We prove that the synergy between atomically dispersed iron and doped sulfur accelerates the reversible electrochemical conversion reactions in Li–S batteries. The FeNSC/S hybrid cathode exhibits superior long-term cycling stability even at a high current density of 1C, with only 0.047% capacity decay per cycle over 1000 cycles. This study demonstrates a novel method for improving the conversion of polysulfides based on electrocatalysis strategies to ultimately obtain high-performance Li–S batteries.