Electrochemical Study on Charge-Discharge Performance of Lithium/Polyazulene Battery

Electrodeposited polyazulene (PAz) films show high electroactivity and fast redox switching behavior when polymerized under suitable conditions. Such PAz films are more electroactive than electrodeposited polypyrrole or polyaniline and were successfully applied in a rechargeable lithium battery. We determined suitable polymerization conditions so as to obtain an electroactive PAz film possessing the highest charge-storing ability and fastest electrode processes. Specifically, the electrochemical kinetics (anion doping-undoping process) of PAz films was investigated by varying the polymerizing current density and formation charge. Charge capacity showed a maximum value when polymerized at 1.4 mA cm⁻² by passage of 5C cm⁻². Cyclic voltammograms coupled with scanning electrons microscope observation of PAz films evidenced that a highly electroactive PAz film can be prepared at 1.4 mA cm⁻². The charge-discharge property and cyclability of Li/LiClO₄/PAz batteries were studied. Li/LiClO₄/PAz batteries showed fairly high and flat discharge voltage (ca. 3.2V), while maintaining 100% coulombic efficiency when charging by ca. 45% of doping level (per unit cathode weight). The Li/LiClO₄/PAz battery performed best when PAz film was formed at 1.4 mA cm⁻² by passage of 5C cm⁻².