Atomically Dispersed and O, N-Coordinated Mn-Based Catalyst for Promoting the Conversion of Polysulfides in Li2S-Based Li-S Battery.

Nowadays, Li-S batteries are facing many thorny challenges like volume expansion and lithium dendrites on the road to commercialization. Due to the peculiarity of complete lithiation and the capability to match non-lithium anodes, Li2S-based Li-S batteries have attracted more and more attention. Nevertheless, the same notorious shuttle effect of polysulfides as in traditional Li-S batteries and the poor conductivity of Li2S lead to sluggish conversion reaction kinetics, poor Coulombic efficiency, and cycling performance. Herein, we propose the interconnected porous carbon skeleton as the host, which is modified by an atomically dispersed Mn catalyst as well as O, N atoms (named as ON-MnPC) via the melt salt method, and introduce the Li2S nanosheet into the carbon host with poly(vinyl pyrrolidone) ethanol solution. It has been found that the introduction of O, N to bind with Mn atoms can endow the nonpolar carbon surface with ample unsaturated coordination active sites, restrain the shuttle effect, and enhance the diffusion of Li+ and accelerate the conversion reaction kinetics. Besides, due to the ultra-high catalyst activity of atomically dispersed Mn catalysts, the Li2S/ON-MnPC cathode shows good electrochemical performance, e.g., an initial capacity of 534 mAh g-1, a capacity of 514.18 mAh g-1 after 100 cycles, a high retention rate of 96.23%, and a decay rate of 0.04% per cycle. Hence, use of atomically dispersed Mn catalysts to catalyze the chemical conversion reactions of polysulfides from multiple dimensions is a significant exploration, and it can provide a brand-new train of thought for the development and commercialization of the economical, high-performance Li2S-based Li-S batteries.