Engineering single-atom catalysts as multifunctional polysulfide and lithium regulators toward kinetically accelerated and durable lithium-sulfur batteries.

• Single atom catalyst with Co-N 4 coordination has been precisely synthesized. • The interconnected 2D network can alleviate the formation of Li-dendrites. • Co-N 4 center suppress the shuttle effect and reduce the reaction energy barrier. • The correlation between the Co-N 4 sites and catalytic activity is deciphered. • The batteries exhibit superior electrochemical performance. Developing electrocatalyst to ameliorate the shuttling effect of lithium polysulfides (LiPSs), sluggish sulfur redox reaction kinetics and the rampant dendrite growth is of paramount importance for lithium-sulfur (Li-S) batteries. Yet still, the utilization of the most mainstream traditional metal electrocatalytic nanoparticles is far below expectation. Herein, we engineer an exclusive single-atom catalyst with planar Co-N 4 coupling of nitrogen-doped graphene mesh (SA-Co/NGM) to achieve exceptional atom utilization efficiency for catalytic conversion of LiPSs. High surface area and ultra-thin two-dimensional texture can not only accommodate high concentration monodispersed lithiophilic atomic Co sites, but also guarantee homogenize high-flux Li ion transport, alleviating the formation of Li-dendrites. Critically, the maximized exposure of Co-N 4 as a regulator in sulfur electrochemistry can conspicuously suppress the shuttle effect and accelerate bidirectional sulfur redox kinetics via electron delocalization, as demonstrated by a judicious combination of electro-kinetic analysis, in situ spectroscopy and density functional theory (DFT) computations. As expected, the batteries based on a SA-Co/NGM modified separator achieve an ultrahigh rate capability, exceptionally long cycle life and a distinguished favorable areal capacity under high sulfur loading. This work provides a rational design of single-atom catalysts for kinetics-boosted electrocatalysis towards long-lasting Li-S batteries. [ABSTRACT FROM AUTHOR]