Fluorine-Doped Fe2O3 as High Energy Density Electroactive Material for Hybrid Supercapacitor Applications

Nanostructured -Fe2O3 with and without fluorine substitution were successfully obtained by a green route, that is, microwave irradiation. The hematite phase materials were evaluated as a high-performance electrode material in a hybrid supercapacitor configuration along with activated carbon (AC). The presence of fluorine was confirmed through X-ray photoelectron spectroscopy and transmission electron microscopy. Fluorine-doped Fe2O3 (F-Fe2O3) exhibits an enhanced pseudocapacitive performance compared to that of the bare hematite phase. The F-Fe2O3/AC cell delivered a specific capacitance of 71Fg(-1) at a current density of 2.25Ag(-1) and retained approximately 90% of its initial capacitance after 15000cycles. Furthermore, the F-Fe2O3/AC cell showed a very high energy density of about 28Whkg(-1) compared to bare hematite phase (approximate to 9Whkg(-1)). These data clearly reveal that the electrochemical performance of Fe2O3 can be improved by fluorine doping, thereby dramatically improving the energy density of the system.