Polymers and copolymers of pyrrole and thiophene as electrodes in lithium cells

M. I. SÁNCHEZ DE PINTO,; H. T. MISHIMA,; B. A. LÓPEZ DE MISHIMA

JOURNAL OF APPLIED ELECTROCHEMISTRY

SPRINGER

Lugar: Berlin; Año: 1997 vol. 27 p. 831 - 838

0021-891X

The performance of pyrrole and thiophene polymer electrodes in lithium cells has been examined inthe lithium perchlorate-propylene carbonate electrolyte by cyclic voltammetry. Polypyrrole filmswere synthesized in 'wet' and 'dry' conditions; pyrrole and thiophene copolymers were prepared atdifferent potentials and bilayers were prepared by sequential deposition of polythiophene (PTh) and polypyrrole (PPy) films. The polymers were cycled between 2.0 V and 4.0 V in the lithium cells. The effects of disconnecting the electrodes from the cell on the behaviour of the polymers regarding doping and coulombic efficiency were also studied. The cycling performance of the 'wet' PPy is better than 'dry' PPy, bilayer PTh/PPy and copolymers. No mixed behaviour was observed for a bilayer where the inner layer was polythiophene and the outer layer was polypyrrol with a thickness PPy/Pth ratio equal to ten. The copolymer prepared at 3.9V vs Li/Li+ showed the higher energy capácity in Vhkg~1 calculated from the anodic charge.