A high charging-discharging efficiency was obtained for Li/LiClO4-PC (propylene carbonate)/PPy (polypyrrole) battery, when a PPy film formed in LiPF6/PC by electropolymerization was used in a LiClO4 electrolyte after PF6- anion undoping. The anion doping-undoping process for the PPy film electrodes was examined with the usual electrochemical techniques. A Li/LiClO4/PPy cell was also tested with a constant current charging-discharging performance. The relationship between sweep rate and anodic peak current shown in the cyclic voltammograms obtained for the PPy film formed in the LiClO4 electrolyte indicates a typical diffusion-controlled process, while a reaction-controlled process was found to be involved in the PPy film electrode formed in the LiPF6 electrolyte. The relationship between undoping level and elapsed time indicated that the diffusion rate of the ClO4- doped in the PPy film formed in LiPF« has a higher value than that of the ClO4- doped in the PPy film formed in LiClO4. SEM observations showed that the PPy films formed in LiPF6 were rougher than those formed in LiClO4. Infrared (IR) spectral measurements confirmed that there are no essential differences in the manner of bonding of the PPy films formed in LiPF6 (PPy+PF6-) and LiClO4 (PPy+ClO4-). Consequently, a morphology of the PPy films was suggested to be a very important factor in determining the kinetics of the anion doping-undoping process and, therefore, charging-discharging properties of Li/LiClO4-PC/PPy battery.
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