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

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.