Improved supercapacitive performance in electrospun TiO2 nanofibers through Ta-doping for electrochemical capacitor applications

Abstract

Here, we report a facile, cost effective, and potentially scalable electrospinning technique to synthesize TiO2 nanofibers and Ta-doped TiO2 nanofibers. The nanofibers were characterized through various characterization techniques such as FESEM, TEM, XRD, FTIR, Raman spectroscopy, BET surface area analysis and XPS. The specific capacitance values for TiO2 nanofibers, 2% Ta doped TiO2 nanofibers and 5% Ta doped TiO2 nanofibers at scan rate of 5 mV s−1 were found to be 111 F g−1, 199 F g−1 and 146 F g−1, respectively in 1 M H2SO4 aqueous electrolyte. TiO2 nanofibers and Ta doped TiO2 nanofibers exhibit excellent cycling stability (100% retention in specific capacitance up to 3000 cycles). The superior charge storage performance of 2% Ta doped TiO2 nanofibers was found due to enhanced electrical conductivity of material, and facile charge transport. The 2% Ta doped TiO2 nanofibers based symmetric supercapacitor device was fabricated and showed specific capacitance of 81 F g−1 at current density of 0.1 A g−1 which remained 46 F g−1 when current density increased to 5 A g−1 in 1 M H2SO4 aqueous electrolyte. The energy density of symmetric supercapacitor was found to be 11.25 W h kg−1 at power density of 100.49 W kg−1, which remained as 6.32 W h kg−1 at higher power density of 6504.3 W kg−1. Further, 2% Ta doped TiO2 nanofibers based symmetric supercapacitor also showed an excellent cycling stability up to 5000 charge-discharge cycles. This study indicates the potential of Ta doping in achieving high energy density symmetric supercapacitor device.