A novel hybrid supercapacitor with a carbon nanotube cathode and an iron oxide/carbon nanotube composite anode

Abstract

A scalable spray deposition technique has been adopted to the fabrication of a flexible nanostructured hybrid supercapacitor based on thin film multi-walled carbon nanotube (MWNT) cathodes and hematite (α-Fe₂O₃)/MWNT composite anodes. On the basis of the total weight of the binder-free MWNT and α-Fe₂O₃/MWNT thin film composite electrodes, the hybrid supercapacitor provided a very high specific energy density of 50 Wh kg⁻¹ at a specific power density of 1000 W kg⁻¹ over the potential range 0–2.8 V, which was an energy density 8 times that of identically prepared symmetric supercapacitors with MWNT only electrodes under the same conditions. The superior electrochemical performance of the hybrid supercapacitor arrangement can be attributed to the incorporation of MWNTs into the α-Fe₂O₃ anodes, which leads to a decrease of internal resistance and an improvement in both the ion diffusion behaviour and the integrity of the α-Fe₂O₃ containing films.