Synthesis of ruthenium oxide coated ordered mesoporous carbon nanofiber arrays as a catalyst for lithium oxygen battery

Li-O2 batteries with super-high theoretical energy density are attracting extensive attention. However, the sluggish oxygen reduction/evolution reaction, the huge volume change from O2/Li2O2 conversion and the undesired electrolyte decomposition in cathode limit their performance. Herein we show design and synthesis of RuO2-coated ordered mesoporous carbon nanofiber arrays by using a natural crab shell template as a catalyst for Li-O2 battery, exhibiting several advantage features. First, the ordered mesopores in nanofibers facilitate electrolyte penetration and electron/ion transfer. In addition, the macro-sized voids between the nanofibers provide efficient buffer space for O2/Li2O2 accommodation and improve O2 diffusion. Furthermore, the uniform RuO2-coating layer alleviates undesired electrolyte decomposition and enhances the surface electronic conductivity. As a result, the battery displays high performance, including high capacity (20600 mAh g−1 at a current density of 100 mA g−1), high rate (9750 mAh g−1 at a current density of 1000 mA g−1) and long-life (300 cycles at a fixed capacity of 1000 mAh g−1).