A Study of Chemically Synthesized Polypyrrole as Electrode Material for Battery Applications

We have studied the behavior of a chemically synthesized polypyrrole as electrode material. The different electrochemical methods that we have used for this characterization, namely, cyclic voltammetry, ac impedance measurements, and cyclic chronopotentiometry, have evidenced the role of the low frequency capacitance characteristic of the doped state of polypyrrole. This capacitance seems independent of the synthesis conditions of the polymer, and we show that it partially explains the large value of the total charge stored in this polypyrrole. Analyzing the effect of residual water in the polymer, we show that a water content of about 3% (w/w) increases the total charge and lowers the redox potential . A quasi linear relationship has been found between and , the massic capacity: increases when decreases. This relation can be also attributed to the charging of the capacitance , where is the degradation potential. We discuss the origin of this capacitance .