Atomic Tungsten on Graphene with Unique Coordination Enabling Kinetically Boosted Lithium-sulfur Batteries.

The employment of catalytic materials is regarded as the most desirable strategy to cope with sluggish kinetics of lithium polysulfides (LiPSs) transformation and severe shuttle effect within lithium-sulfur batteries (LSBs). Single-atom catalysts (SACs) with 100% atom-utilization possess competitive advantages to serve as both anchoring and electrocatalytic centers for LiPSs. However, it's still a great challenge due to the insufficiency of facile synthetic strategy and ambiguity of the structure-property relationships. Herein, a novel kind of tungsten (W) SAC immobilized on nitrogen-doped graphene (W/NG) with a unique W-O2N2-C coordination configuration and a high W loading of 8.6 wt% is first proposed via a self-template and self-reduction strategy. The special local coordination environment of W atom endows the W/NG with elevated LiPSs adsorption ability and catalytic activity evidenced by combination of experimental and theoretical studies. Impressively, LSBs equipped with W/NG modified separator manifest greatly improved electrochemical performances with high cycling stability over 1000 cycles and ultrahigh rate capability. Moreover, it indicates high areal capacity of 6.24 mAh cm-2 with robust cycling life at a high sulfur mass loading of 8.3 mg cm-2 .