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.