In-situ engineered polycrystalline phases in polyaniline-multiwalled carbon nanotubes composite exhibiting unique mechanism of charge storage

Abstract

We report on a template/surfactant free, simple chemical synthesis, material properties, electrochemical behavior, and device performance of semi-polycrystalline polyaniline- multiwalled carbon nanotube (SPani-MWNT) composite as supercapacitor electrode. The specific capacitances (Csp) exhibit a unique, yet interesting pattern attributable to the presence of crystalline phases in the material. The electrode delivers a Csp of 359 F g−1 at a current density (CD) of 1 A/g, which declines to a lower value of 257 F g−1 at 5 A/g and gains a higher value of 444 F g−1 at 10 A/g in a 3-electrode cell configuration using 1 M aq.Na2SO4 as an electrolyte. Similar pattern of results is observed during performance of SPani-MWNT∥SPani-MWNT in a 2-electrode symmetrical device configuration with polymer gel electrolyte (xanthan gum in 1 M aq.Na2SO4). The device delivers a Csp of 56 F g−1, energy density of 5 Wh Kg−1, and a power density of 365 W kg−1 at an applied CD of 0.5 A/g. At a higher CD of 10 A/g, the device delivers energy density of ∼4 Wh kg−1 and power density of 6.7 kW kg−1. In addition, the device exhibits good electrochemical reversibility with cycling stability, retention of ∼80 % of its initial capacitance and 99 % of initial coulombic efficiency over 10,000 continuous GCD cycles at an applied CD of 0.5 A/g. The results indicate excellent rate capability and power management.