Dual-Atoms Iron Sites Boost the Kinetics of Reversible Conversion of Polysulfide for High-Performance Lithium-Sulfur Batteries

Abstract Atomically dispersed metal catalysts have offered significant potential for accelerating sluggish kinetics of transformation of lithium polysulfide(LiPS) and inhibiting the shuttle effect to achieve the long-life cycling and high rate of lithium sulfur batteries. However, the end-on adsorption structure between single metal site and polysulfide limits the adsorption capacity and catalytic activity of single atom catalysts. Here, we construct dual-atoms iron sites on nitrogen doped graphene to serve as highly efficient catalyst for lithium sulfur batteries. As expected, the dual-atoms sites can firmly bound polysulfides by forming double Fe-S bonds between polysulfides and the two adjacent iron atoms. Such double-bond adsorption structure is also favorable for the electron transfer and polysulfides activation, so as to reduce the energy barrier and accelerate the reaction kinetics. As a result, the as-obtained dual-atoms iron catalyst can effectively alleviate the shuttle effect and improve the utilization of active sulfur, thus the batteries present high initial capacity of 1615 mAh g-1 at 0.05 C and long-cycle life with a decay rate per cycle as low as 0.015% at 2C over 1000 cycles.