Carbon-Free CoO Mesoporous Nanowire Array Cathode for High-Performance Aprotic Li–O<sub>2</sub> Batteries

Although various kinds of catalysts have been developed for aprotic Li–O<sub>2</sub> battery application, the carbon-based cathodes are still vulnerable to attacks from the discharge intermediates or products, as well as the accompanying electrolyte decomposition. To ameliorate this problem, the free-standing and carbon-free CoO nanowire array cathode was purposely designed for Li–O<sub>2</sub> batteries. The single CoO nanowire formed as a special mesoporous structure, owing even comparable specific surface area and pore volume to the typical Super-P carbon particles. In addition to the highly selective oxygen reduction/evolution reactions catalytic activity of CoO cathodes, both excellent discharge specific capacity and cycling efficiency of Li–O<sub>2</sub> batteries were obtained, with 4888 mAh g<sub>CoO</sub><sup>–1</sup> and 50 cycles during 500 h period. Owing to the synergistic effect between elaborate porous structure and selective intermediate absorption on CoO crystal, a unique bimodal growth phenomenon of discharge products was occasionally observed, which further offers a novel mechanism to control the formation/decomposition morphology of discharge products in nanoscale. This research work is believed to shed light on the future development of high-performance aprotic Li–O<sub>2</sub> batteries.