Performance of Zn rechargeable cells having Polypyrrole cathodes doped with surfactant anion

Abstract

Currently there exists a very high demand for electrochemical energy storage devices such as rechargeable cells and super capacitors due to massive increase in the use of portable electronics. At the moment this demand is mainly supplied by Li based cells. However, due to high cost, rapid reactivity and issues in disposal of Li, attention has been diverted on non Li based cells. Zn has been identified as a good candidate to replace Li. Even though several Zn based rechargeable cells were reported, not much work has been carried out on cells with conducting polymer cathode based Zn cells. In this study, performance of Zn rechargeable cells fabricated with conducting polymer polypyrrole (PPy) doped with a surfactant anion is reported. PPy films were galvanostatically electro polymerized on to stainless steel disc and cells were assembled with a polyvinylidenefluoride based gel polymer electrolyte having zinc-trifluoromethanesulfonate as the salt. Cells having different cathode thicknesses were fabricated and were characterized using cyclic voltammetry, electrochemical impedance spectroscopy and continuous charge-discharge tests. Cells exhibited open circuit voltages between 0.9-1.0 V. Cycling testes showed that cycleable capacity almost follows the thickness variation of the cathode. Continuous charge-discharge tests revealed that the capacity decrease with the cycle number was higher in thinner films.