The Synergistic Effect of Nickel Cobalt Sulfide Nanoflakes and Sulfur-doped Porous Carboneous Nanostructure as Bifunctional Electrocatalyst for Enhanced Rechargeable Li-O2 Batteries

•The NiCo2S4 sulfur-doped carbon nanostructure catalyst is developed by the one-step method.•The composite catalyst shows an excellent bifunctional activity for ORR and OER reactions.•The effects of NiCo2S4 and sulfur loading on the carbon surface are investigated.•A Li-O2 battery with NCS/S-3DPG cathode operates over 1704 h with low overpotential.