▎ 摘　　要

Self-assembled manganese cobalt oxide (Mn0.5Co2.5O4) nanofibers sandwiched in graphene sheets (Mn0.5Co2.5O4@G) are successfully synthesized by a hydrothermal treatment and annealing process. Owning to the unique sandwich-like structures, rich active sites, and boosted electrical conductivity, Mn0.5Co2.5O4@G composite demonstrates superior electrochemical performance for potential supercapacitors. In a three-electrode system, it exhibits excellent cycling stability with a specific capacitance retention of 93.8% after 10 000 cycles at a current density of 10 A g(-1,) and achieves specific capacitances of 617 and 434 F g(-1) at the ultrahigh current densities of 30 and 40 A g(-1), respectively. For an asymmetric supercapacitor of Mn0.5Co2.5O4@G/AC, high energy densities of 36.8 and 13.6 W h kg(-1) are also achieved at power densities of 147.3 and 3755.8 W kg(-1), respectively. It is believed that the synthesized Mn0.5Co2.5O4@G composite can be a promising electrode material for high-performance supercapacitors, and the present synthetic strategy can be further extended for designing many other functional composites with desirable nanostructures and performance.