NiCo2O4 nanosheets supported on Ni foam for rechargeable nonaqueous sodium–air batteries

• In this paper, we fabricated a composite electrode of NiCo2O4 nanosheets/Ni foam by a solvothermal method.
• We examined its electrochemical behaviors in the Na–air battery.
• We observed Na2O2 nanosheets after the discharge of Na–air battery.
• We proposed NiCo2O4 nanosheets/Ni foam as a promising air electrode for rechargeable sodium–air batteries.

NiCo2O4 nanosheets supported on Ni foam were synthesized by a solvothermal method. A composite of NiCo2O4 nanosheets/Ni as a carbon-free and binder-free air cathode exhibited an initial discharge capacity of 1762 mAh g− 1 with a low polarization of 0.96 V at 20 mA g− 1 for sodium–air batteries. Na2O2 nanosheets were firstly observed as the discharged product in sodium–air battery. High electrocatalytic activity of NiCo2O4 nanosheets/Ni made it a promising air electrode for rechargeable sodium–air batteries.