Pulse polymerized polypyrrole electrodes for high energy density electrochemical supercapacitor

A novel method of pulsed polymerization for pyrrole exhibiting highest capacitance and very high energy density polypyrrole supercapacitor is reported. Stable polypyrrole films with good electrochemical reversibility and high doping degree were obtained by applying ultra short on time current pulse for polymerization. Pulse on time plays an important role in controlling chain size and chain defects whereas pulse off time contributes in polymer conjugation and orientation. A regime of pulse on time is identified to yield highly capacitive and stable films for supercapacitor application. Very high specific capacitance of 400 F/g and an unexpectedly high energy density of 250 Wh/kg were obtained form pulsed polymerized ordered polypyrrole structures in acidic electrolyte. Stability tests performed on pulsed polymerized pPy electrode yield long cycling life up to 10,000 cycles at charge/discharge current density of 5 mA/cm2.