Direct synthesis of ACo₂O₄ (A = Ni, Cu, Fe, Zn) nanowires on carbon cloth as an oxygen electrode catalyst for rechargeable lithium-oxygen batteries

Developing a low-cost, stable and efficient oxygen electrode catalyst for use in lithium-oxygen batteries with a long cycling stability and a high discharge/charge capacity is very important for solving the energy crisis and reducing environmental pollution. In this study, ACo₂O₄ (A = Ni, Cu, Fe, Zn) nanowires grown on carbon cloth (CC) were readily synthesized via a hydrothermal method with a subsequent heat treatment. NiCo₂O₄ nanowires grew and crossed each other to randomly form many hedges with a three-dimensional network structure. The NiCo₂O₄/CC electrode has the higher specific surface area and more mesopores than the other ACo₂O₄/CC (A = Cu, Fe, Zn) electrodes. The NiCo₂O₄/CC electrode can cycle over 200 times under a limited capacity of 0.3 mA h cm⁻² (500 mA h g⁻¹) at 0.2 mA cm⁻² (340 mA g⁻¹) and show a discharge capacity of up to 6.2 mA h cm⁻² (10541 mA h g⁻¹) at 0.12 mA cm⁻² and 4.75 mA h cm⁻² (8076 mA h g⁻¹) at 0.24 mA cm⁻², reaching 2861.8 and 2674.5 Wh kg⁻¹ at 0.12 and 0.24 mA cm⁻², respectively.