▎ 摘　　要

Large over-potentials during battery operation remain a big obstacle for aprotic Li-O-2 batteries. Herein, a nanocomposite of about 4 nm cobalt monoxide nanocrystals grown. in situ on reduced graphene oxide substrates (CoO/RGO) has been synthesized via a thermal decomposition method. The CoO/RGO cathode delivers a high initial capacity of 14 450 mAh g(-1) at a current density of 200 mA g(-1). Simultaneously it displays little capacity fading after 32 cycles with a capacity restriction of 1000 mAh g(-1). Additionally, compared with Ketjenblack and general CoO nanoparticles, ultrathin CoO nanoparticle-decorated RGO electrode materials with a delaminated structure display an observable reduction of over-potential in Li-O-2 batteries. These results demonstrate that the introduction of RGO improves the performance of CoO, which is a promising strategy for optimizing the design of electrocatalysts for aprotic rechargeable Li-O-2 batteries.