Three-dimensional graphene/amorphous porous cobalt molybdenum phosphide nanosheet structure as polysulfide transformation promoters for Li-S batteries

Abstract

The slow transformation kinetics of polysulfides (PSs) lead to the poor cyclic stability of sulfur cathode. It is necessary to select suitable electrocatalysts to achieve efficient transformation of PSs. Hindered electron transfer and limited active sites on the surface of the electrocatalyst severely degrade the catalytic performance. Herein, a unique three-dimensional graphene/amorphous porous CoMoP (3DG@CoMoP) nanosheet structure is prepared through thermochemical vapor deposition and template etching methods. The unique nanosheet structure coupled with amorphous structure builds fast channels for electron and ion transfer, providing rich adsorptive and catalytic active sites for PSs conversion, thus endowing 3DG@CoMoP with prominent electrocatalytic activity for PSs redox reactions. Resultantly, the 3DG@CoMoP cathode display an initial capacity of 794 mAh g^-1 and a reserved capacity of 564 mAh g^-1 at 1 C after 1000 cycles (the decay rate of each cycle is only 0.029%). This work exhibits a novel way to design efficient electrocatalysts with rich active sites.