Fabrication of Binder-free TiO2 Nanoparticle Electrodes for Supercapacitor in Low-Power Electronic Applications

In the present work, supercapacitor performance of binder-free TiO2 nanoparticles electrodes, fabricated via a facile, cost effective electrophoretic deposition (EPD) technique has been analyzed. To enhance the electrical conductivity and adhesion of coated TiO2 nanoparticles thin film over the graphite substrate, an optimized amount (2 wt. %) of multiwalled carbon nanotubes (MWCNTs) is added into the dispersion of TiO2 nanoparticles. Uniform and smooth surface morphology of fabricated electrodes has been analyzed using field emission scanning electron microscope (FESEM). The electrochemical analysis of the electrodes is done in a three-electrode configuration cell with 2M KOH electrolyte through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). Electrochemical analysis reveals that the best optimized TiO2 nanoparticles electrode having 2 wt.% MWCNTs displays an enhanced specific capacitance of $320 \pm 5$ Fg−1 at 1 Ag−1 current density. The fabricated electrode displays a higher diffusion coefficient $\sim 1.45\times 10^{-10}\text{cm}^{2}\mathrm{s}^{-1}$ and a small relaxation time constant $(\tau_{\mathrm{o}}=89\ \text{ms})$ in 2M KOH. Moreover, fabricated TiO2 nanoparticles electrode maintains 87 % capacity retention after 1000 charge/discharge cycles. We believe this study would be helpful in the designing of practical supercapacitor devices for low-power electronic applications.