Modulating Electronic Structure with Copper Doping to Promote the Electrocatalytic Performance of Cobalt Disulfide in Li-O Batteries.

Introducing heteroatom into catalyst lattice to modulate its intrinsic electronic structure is an efficient strategy to improve the electrocatalytic performance in Li-O batteries. Herein, Cu-doped CoS (Cu-CoS ) nanoparticles are fabricated by a solvothermal method and evaluated as promising cathode catalysts for Li-O batteries. Based on physicochemical analysis as well as density functional theory calculations, it is revealed that doping Cu heteroatom in CoS lattice can increase the covalency of the CoS bond with more electron transfer from Co 3d to S 3p orbitals, thereby resulting in less electron transfer from Co 3d to O 2p orbitals of Li-O species, which can weaken the adsorption strength toward Li-O intermediates, decrease the reaction barrier, and thus improve the catalytic performance in Li-O batteries. As a result, the battery using Cu-CoS nanoparticles in the cathode exhibits superior kinetics, reversibility, capacity, and cycling performance, as compared to the battery based on CoS catalyst. This work provides an atomic-level insight into the rational design of transition-metal dichalcogenide catalysts via regulating the electronic structure for high-performance Li-O batteries.