Potentiodynamically Deposited Polyaniline on Stainless Steel Inexpensive, High-Performance Electrodes for Electrochemical Supercapacitors

Polyaniline ~PANI! has been studied as an active material for electrochemical capacitors. Polymerization of aniline to PANI has
been carried out potentiodynamically on a stainless steel ~SS! substrate, instead of Pt-based substrates generally employed for this
application. The PANI/SS electrodes have been evaluated by assemb领 symmetrical capacitors in NaClO4 1 HClO4 mixed
electrolyte and subjecting them to galvanostatic charge/discharge cycles between 0 and 0.75 V. The effect of substrate has been
assessed by comparing the capacitance of PANI/SS and PANI/Pt electrodes. The capacitance of PANI/SS electrode is higher than
that of PANI/Pt electrode by several times. The effect of sweep rate of potentiodynamic deposition of PANI/SS on capacitance has
been investigated. At a power density of 0.5 kW kg21, a capacitance value of 815 F g21 of PANI is obtained for the deposition
sweep rate of 200 mV s21. Increase in thickness of PANI on the SS substrate results in an increase in capacitance of PANI. This
value of capacitance is the highest ever reported for any electrochemical capacitor material. Thus, in addition to a favorable
economic aspect involved in using SS instead of Pt or Pt-based substrate, the advantage of higher capacitance of PANI has also
been achieved.