Regulating Electronic Structure of Fe–N4 Single Atomic Catalyst via Neighboring Sulfur Doping for High Performance Lithium–Sulfur Batteries

Abstract

AbstractConstructing high performance electrocatalysts for lithium polysulfides (LiPSs) adsorption and fast conversion is the effective way to boost practical energy density and cycle life of rechargeable lithium–sulfur (Li–S) batteries, which have been regarded as the most promising next generation high energy density battery but still suffering from LiPSs shuttle effect and slow sulfur redox kinetics. Herein, a single atomic catalyst of Fe–N4 moiety doping periphery with S (Fe–NSC) is theoretically and experimentally demonstrated to enhance LiPSs adsorption and facilitated sulfur conversion, due to more charge density accumulated around Fe–NSC configuration relative to bare Fe–N4 moiety. Thereafter, the graphene oxide supported Fe–NSC catalyst (Fe–NSC@GO) is modified to the commercial separator through a simple slurry casting method. Thus, Li–S cells with Fe–NSC@GO modified separators display high discharge capacity and excellent cyclability, showing 1156 mAh g−1 at 1 C rate and a low capacity decay of only 0.022% per cycle over 1000 cycles. Even with a high sulfur loading of 5.1 mg cm−2, the cell still delivers excellent cycling stability. This work provides a fresh insight into electrocatalyst structural tuning to improve the electrochemical performance of Li–S batteries.