Electrochemical performance of supercapacitors based on carbon nanofoam composite and microporous poly(3, 4-ethylenedioxythiophene) thin film asymmetric electrodes

Abstract

Electrochemical performance of supercapacitors configured using carbon nanofoam enfolded by conformal thin poly(3,4-ethylenedioxythiophene) (PEDOT) film in nanofibrous structure and electrodeposited microporous PEDOT film/graphite as two asymmetric electrodes is described. Cyclic voltammetry data at 20 mV s−1 scan rate show specific capacitance of carbon nanofoam-PEDOT composite electrode operating in the −0.8 to +0.2 V, and microporous PEDOT in the 0 to +0.8 V voltage range are 72 and 159 F g−1, respectively. Paired in an asymmetric supercapacitor, in the balanced charge state, highly symmetrical cyclic voltammetry plots at high scan rates of 100 mV s−1 in −0.8 to +1.2 V voltage range testify highly capacitive behavior with high degree of charge reversibility. This is attributed to unimpeded pore-filling and alignment of ionic charges over vast interiors of carbon nanofoam and a highly pervasive access to electrolyte ions within interconnected void network of microporous PEDOT. Linear charge-discharge characteristic of the supercapacitor at 1.0 to 3.5 A g−1 current density show high rate capability and yield energy density of 13.6 Wh kg−1 at the power density of 19.0 kW kg−1. The long term charge-discharge tests at 1 A g−1 show minimal ∼14% loss of specific capacitance of asymmetric supercapacitor for 10,000 cycles.