Construction of Hierarchical FeCoO@MnO Core-shell Nanostructures on Carbon Fibers for High-performance Asymmetric Supercapacitor

In this work, the novel hierarchical FeCoO@MnO core-shell nanosheet arrays have been synthesized by a facile hydrothermal method, which are grown directly on a flexible carbon fiber (CF) as an integrated electrode for supercapacitors. Scanning electron microscopy and high-resolution transmission electron microscopy measurements illustrate that MnO nanoflakes uniformly wrap around the surface of two-dimensional FeCoO nanosheets. The electrode exhibits high areal capacitance of 4.8Fcm at a current density of 1mAcm. Moreover, an asymmetric FeCoO@MnO//active carbon (AC) cell is successfully fabricated. The asymmetric supercapacitor (ASC) displays high energy density/power density (22.68Whkg at 406.01Wkg and 7.06Whkg at 1802.5Wkg), as well as excellent cycling stability with 90.1% of the initial capacitance after 5000 continuous cycles. Moreover, two ASCs connected in series can light a LED. These performances demonstrate great potential of the designed ASC in the field of energy storage due to their remarkable electrochemical properties.