The synergistic effect of nickel cobalt sulfide nanoflakes and sulfur-doped porous carboneous nanostructure as bifunctional electrocatalyst for enhanced rechargeable Li-O2 batteries

Abstract

Herein, NiCo2S4 supported on sulfur-doped carbon with multi-porous nanostructures are developed to achieve excellent bifunctional catalytic activities. We present a comprehensive study on the composite effect between NiCo2S4 and sulfur-doped carbon as a bifunctional catalyst for oxygen reduction reaction and oxygen evolution reactions. Further, the high catalytic activities of NiCo2S4 modified sulfur-doped carbon composite are explored as an air cathode for rechargeable Li-O2 batteries. The sulfur-doped carbon surface modification with NiCo2S4 improves the reversibility and capacity due to its high specific surface area, exposing of large active sites, and the formation of smaller sized toroidal Li2O2 discharge product on cathode, which can be decomposed at a lower potential compared to a pristine carbon electrode. The Li-O2 battery constructed with the rationally designed composite air cathode delivers ultra-high discharge capacity of 14,173 mA hg−1 at 150 mAg−1 and superior cyclability for over 1704 h without capacity fade due to the excellent surface properties.