Expediting redox kinetics of sulfur species by atomic-scale electrocatalysts in lithium-sulfur batteries

Lithium-sulfur (Li-S) batteries have extremely high theoretical energy density that make them as promising systems toward vast practical applications. Expediting redox kinetics of sulfur species is a decisive task to break the kinetic limitation of insulating lithium sulfide/disulfide precipitation/dissolution. Herein, we proposed a porphyrin-derived atomic electrocatalyst to exert atomic-efficient electrocatalytic effects on polysulfide intermediates. Quantifying electrocatalytic efficiency of liquid/solid conversion through a potentiostatic intermittent titration technique measurement presents a kinetic understanding of specific phase evolutions imparted by the atomic electrocatalyst. Benefiting from atomically dispersed "lithiophilic" and "sulfiphilic" sites on conductive substrates, the finely designed atomic electrocatalyst endows Li-S cells with remarkable cycling stablity (cyclic decay rate of 0.10% in 300cycles), excellent rate capability (1035 mAh g(-1) at 2 C), and impressive areal capacity (10.9 mAh cm(-2) at a sulfur loading of 11.3 mgcm(-2)). The present work expands atomic electrocatalysts to the Li-S chemistry, deepens kinetic understanding of sulfur species evolution, and encourages application of emerging electrocatalysis in other multielectron/multiphase reaction energy systems.