Electropolymerized 1,10-phenanthroline as the electrode material for aqueous supercapacitors

Research on novel conducting polymer material is essential in designing high-performance electrodes for the electrochemical energy storage systems. 1,10-phenanthroline is, for the first time, electropolymerized in aqueous solutions on carbon paper, and the resulting electrodes (PPhen/CP) are utilized to store energy electrochemically. The influence of the electropolymerization time and intercalated anions to the morphology and charge storage performance is investigated, and the results show that PPhen/CP with 20 min electropolymerization time and intercalated sulfate ions (PPhen/CP-20) exhibits the best performance, with the specific capacities estimated by galvanostatic charge–discharge of 111.5 mAh g−1 at 1 A g−1 in 1 M H2SO4, and of 97.1 mAh g−1 at 1 A g−1 in 1 M KOH. The solid-state supercapacitor assembled using two PPhen/CP-20 and the H2SO4/PVA gel electrolyte can deliver the energy density of 19.44 Wh kg−1 at the power density of 899.5 W kg−1, and can retain 80.76% of the initial capacity after cycling at 5 A g−1 for 4000 cycles. The charge storage mechanism involves dihydroxyl/diketone groups redox process and double layer charging, and the charge storage performance is affected by the electrochemically active surface area and diffusion processes which are related to the morphology of the electropolymerized film. This study shows that the electropolymerized 1,10-phenanthroline film is a promising candidate as the electrode material for aqueous supercapacitors.