▎ 摘　　要

Although possessing extremely high energy density, lithium-oxygen (Li-O-2) battery suffered from large charge overpotential, low round-trip efficiency and poor cycling life, which limited the practical application of this smart system. Ru particles functionalized graphene aerogels (Ru-GAs) were designed and directly used as a free-standing cathode for Li-O-2 battery. The Ru-GAs showed hierarchical pores, which had the pore volumes of 2.8 and 14.1 cm(3) g(-1) below and above critical pore diameter of 100 nm. The Ru-GA cathode in Li-O-2 battery delivered a high capacity of more than 12 000 mAh g(-1) and excellent cycling retention, which was mainly attributed to the three-dimensional porosity, abundant active sites with Ru particles and chemical stability arising from the character of binder-free cathode. Based on the results of in situ gas chromatography-mass spectrometry analysis, the reaction mechanism during charge process in aprotic electrolyte was proposed by the theory of three oxidation stages.