Conductive Fe2N/N-rGO composite boosts electrochemical redox reactions in wide temperature accommodating lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries suffer from shuttle effect and slow redox kinetics during cycling, leading to poor performance. Especially, these problems are magnified in wide temperatures, which limit the practical application of Li-S batteries. The application of transition metal with chemisorption and catalysis is an effective strategy to capture the polysulfides and accelerate the conversion rate. Herein, a novel separator modified by iron nitride nanoparticles that evenly dispersed on N-doped graphene (Fe2N/N-rGO) is presented. Fe2N as active catalytic sites reduce the decomposition barrier of lithium sulfide and facilitate the conversion kinetics between lithium polysulfide and lithium sulfide, which improves electrochemical performance. Fe2N still plays a role in speeding up the reaction kinetics at low temperatures, and inhibiting the shuttle of polysulfides at high temperatures. Accordingly, the assembled cells containing Fe2N/N-rGO achieve a long cycle life (average fading of 0.05% per cycle at 1C for 700 cycles) and high rate performance (688 mAh g−1 at 5C). More importantly, the cells deliver high capacity with 1043 mA h g−1 and 778 mA h g−1 at 50 °C and 0 °C, respectively. The work provides a broader idea for the practical application of lithium-sulfur batteries in the future.