Improved supercapacitive charge storage in electrospun niobium doped titania nanowires
Baiju Vidyadharan, Panikar Sathyaseelan Archana, Jamil Ismail, Rajan Jose
Supercapacitors are developing as a desired energy storage medium because of their order of magnitude better power density than batteries and energy density than electronic capacitors. One of the significant challenges in developing a suitable electrode material for supercapacitors is the scarcity of materials with high specific capacitance. In this study, we show that electrospun niobium doped titanium dioxide (Nb: TiO2) nanowires have an order of magnitude greater capacitance (280 F g1) than pristine TiO2 (40 F g1) or zirconium doped TiO2 (30 F g1). The cyclic voltammetry and charge-discharge cycling measurements reveal that the Nb: TiO2 nanowires have 100 per cent coulombic efficiency and can be operated for over 5000 cycles without significant capacitance deterioration. The increased electrical conductivity of Nb: TiO2 is attributed to its higher charge storage capabilities, as shown by electrochemical impedance spectroscopy. An asymmetric functional supercapacitor with an anode of Nb: TiO2 and a cathode of activated carbon is constructed. The device achieved energy densities of 16.3, 11.4, and 5.6 W h kg1 at power densities of 770, 1310, and 1900 W kg1. These results outperform a control device built using activated carbon as both electrodes.
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