Wave-like free-standing NiCo2O4 cathode for lithium-oxygen battery with high discharge capacity

A novel free-standing air electrode for Li-O2 battery with a wave-like microstructure is designed and synthesized through a facile electrochemical deposition process. Interconnected NiCo2O4 nanosheets with planes grown almost parallel to the surface of Ni foam build up continues porous catalytic surface with open space for the growth of Li2O2 discharge product. Li-O2 battery with the synthesized cathode delivers a high discharge capacity of 7004 mAh g−1 at 40 mA g−1 with a charge potential lower than 3.6 V (vs. Li/Li+), and significantly lower impedance compared to conventional electrode. Flower-like Li2O2 particles with a large size are observed as discharge products, consisting with the high discharge capacity. The unique wave-like microstructure and DMSO-based electrolyte with a high-doner-number are proposed to be responsible for the high discharge capacity, and the formation of large size Li2O2 discharge products. In addition, the electrode also exhibits stable cycle performance up to 100 cycles at the current density of 100 mA g−1 due to the robust composition and microstructure of the free-standing design.