Electrochemical cycling stability of nickel (II) coordinated polyaniline

The nickel (II) coordinated polyaniline (PANI-Ni) was designed as active electrode material to improve electrochemical cycling stability of conductive polymer-based supercapacitors. The conductive coordination polymer of PANI-Ni was formed to grow on the substrate of carbon paper through the hydrothermal coordination reaction between Ni(Ac)2 and PANI. PANI-Ni with intrachain and interchain coordination structure could reinforce the polymer molecule chain strength to overcome volumetric swelling and shrinking during charge/discharge process. The specific capacitance was obviously improved from 234.5 F g−1 for bare PANI to 417 F g−1 for PANI-Ni in 1 M H2SO4 electrolyte at a current density of 1 A g−1 and a potential window of 0.8 V. PANI-Ni electrode shows the cycling capacitance retention of 93% after 1000 cycles at 5 A g−1. It also showed low capacitance loss of only 12% when the current density increased from 1 to 5 A g−1, presenting high rate capability. The symmetric PANI-Ni supercapacitor was constructed using PANI-Ni electrode and H2SO4 involved polyvinyl alcohol gel electrolyte. PANI-Ni supercapacitor showed the cycling capacitance retention of 83% after 1000 cycles at an output voltage of 1.7 V and a current density of 5 A g−1. PANI-Ni conductive coordination polymer presents the promising application prospect of supercapacitor.