摘要

A novel two-step approach, electrochemical deposition in a cobalt sulfate solution followed by hydro-thermal treatment in a nickel sulfate solution, is used to fabricate nanofibrous NiCo2O4 on carbon fibers for binder-free supercapacitor electrodes. The obtained NiCo2O4 consists of nanofibers and nanoflakes which are connected with each other to form open nanopores in the active material. The material exhibits excellent pseudocapacitive performance with a specific capacitance as high as 1807 F g(-1) at a current density of 1 Ag-1 and a rate capability of 75% at 40Ag(-1). The remarkable electrochemical properties are attributed to the porous structure created by the hydrothermal reaction between oxyhydroxide and Ni2+ ions. Compared to the conventional method based on hydrothermal decomposition of cobalt and nickel nitrates, this approach is more environment-friendly, and when used for preparation of binder-free electrode, it is more effective in confining nanostructred NiCo2O4 growth to a conductive substrate and ensuring good contact between the active material and the substrate.