Polyaniline-based Nitrogen-containing Carbon Electrode Materials For Supercapacitor

Polyaniline was synthesized by solution polymerization, then the activated nitrogen-containing carbon(ANC) was prepared by the pyrolysis and activation of polyaniline as the electrode materials for supercapacitors. The influence of pyrolysis conditions, activation conditions and activation methods on specific capacitance performance of ANC was studied. Activated nitrogen-containing carbon/carbon aerogel composite(ANC/ACA) with different composite ratios was prepared via in-situ polymerization and mechanical mixing methods. The prepared materials were characterized by SEM, nitrogen adsorption and elemental analysis methods and their electrochemical properties were investigated by cyclic voltammetry, galvanostatic charge-discharge and impedance spectroscopy methods.The results showed that the optimal pyrolysis condition of polyaniline was stabilization at 250℃for 4h and pyrolysis at 650℃for 2h. KOH chemical activation had better effect than CO2 physical activation and KOH-CO2 combined activation. ANC had more pore, larger surface area and better specific capacitance owing to the effect of KOH activation. Meanwhile, the nitrogen atoms in ANC interacted with the ions of electrolytes and pseudocapacitance was formed which contributed to the improvement of specific capacitance. Compared with ANC and ANC/ACA, the optimal activated nitrogen-containing carbon (y-ANC) and the optimal activated nitrogen-containing carbon(y-ANC/ACA) prepared in the optimal pyrolysis condition showed better performance due to higher nitrogen contents in y-ANC and y-ANC/ACA. The y-ANC/ACA prepared via in-situ polymerization and mechanical mixing methods showed high specific capacitance due to the introduction of carbon aerogels with high conductivity. Asymmetrical supercapacitors assembled by ANC/ACA as cathode and Ni(OH)2 as anode showed both the double layer capacitance and paeudocapacitance and their specific capacitances were obviously better than those of symmetrical supercapacitors. The prepared ANC/ACA was suitable cathode materials of asymmetrical supercapacitors.