Toward a high specific power and high stability polypyrrole supercapacitors

Polypyrrole (PPy) films doped by p-toluenesulfonic (PTS) are prepared by pulse current polymerization (PCP PPy) in aqueous solutions. Cations (H+, Li+, Na+, and K+ ions) in working electrolyte solutions have a great influence on the electrochemical properties of PCP PPy films for supercapacitors. In 3 M aqueous chloride solutions, the smaller cations lead to the better electrochemical properties of PCP PPy films. PCP PPy films show ideally capacitive characteristics with a very high specific power of 110.9 kW kg(-1) in 3M HCI when its specific energy reaches 18.4 Wh kg(-1). PCP PPy films are very stable in 3M HCI, showing less than 4% decay over 160,000 and 20,000 charge/discharge cycles at current density of 40 A g(-1) within voltage range of 0-0.4 V and 0-0.8 V, respectively. The results of SEM show that many pits and grooves appear on the surface of PPy anode in 3M KCI after 30,000 cycles, which should be main reason of rapid decay of PPy capacitance in 3M KCI. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.