Nb2O5/reduced Graphene Oxide Nanocomposite Anode for High Power Hybrid Supercapacitor Applications.

Hybridizing faradaic and non‐faradaic charge storage mechanisms permits hybrid supercapacitors to achieve desirable high energy‐power characteristics. Although the hybridization approach increases the energy density, discrepancies in the reaction kinetics, especially sluggish charge‐transfer reactions in Faradaic battery‐type electrodes, curtails the power density. To increase the power density of battery‐type electrodes, an orthorhombic phase of niobium pentoxide (Nb2O5) is one of the most prominent contenders because the orthorhombic crystal structure provides two‐dimensional transport channels for fast Li‐ion diffusion. However, such ultrafast Li‐ion diffusion cannot be realized due to its electrical‐insulating nature. Herein, we synthesized a composite of the orthorhombic phase of niobium pentoxide (Nb2O5) interconnected with reduced graphene oxide nanosheets via facile microwave assisted methods. Such a dual‐conductive composite anode exhibits excellent rate performance to match that of the cathode which operates conventional adsorption‐desorption charge storage mechanism. By combining the composite anode with a nitrogen doped reduced graphene oxide (N‐rGO) cathode, the device delivers maximum energy density of 89 Wh kg−1 (at 125 W kg−1), and the energy density of 20 Wh kg−1 is retained even at 3500 W kg−1, which is one of the highest energy density reported for Nb2O5 based HSC to the best of our knowledge. Niobium pentaoxide bridging the gap between Li‐ion batteries and Supercapacitors: A high power hybrid supercapacitor comprising of reduced graphene oxide/Nb2O5 nanocomposite cathode and nitrogen doped reduced graphene oxide cathode delivers high energy and power densities. [ABSTRACT FROM AUTHOR]