Electrochemical Performance Of Nitrogen-Riched Carbon Material

Supercapacitors have attracted considerable attention because of their pulse power supply, long cycle life, and fast charge-discharge speed. In this paper, the Polyaniline/Graphene oxide composite was synthesized using in situ polymerization. Asymmetric supercapacitor was designed which P1G1C8composite was used as positive electrode material and activated carbon was used as negative electrode material. In order to enhance the gravimetric capacitance of the hybrid supercapacitor, the mass matching ratio of two electrodes was adjusted. And at different mass matching ratio, the relationship between the operating voltage range and the comprehensive electrochemical performance of the hybrid supercapacitor was studied.After1000cycles of charge-discharge process, the polyaniline electrode showed poor cycle stability, only maintaining30%of its initial capacitance, while the capacitance retention of P1G1C8of92%was found over1000cycles at the constant current of5mA. When the mass matching ratio of two electrodes (negative/positive) was1.5, the gravimetric specific capacitance of the asymmetric supercapacitor system reached the highest value (22.9mAh/g), with the increasing of the mass matching ratio, the value of the cell gravimetric specific capacitance decrease.The nitrogen-riched mesoporous carbons were synthesized via a facile method combined the advantages of templating and sol-gel processing using phenol (P), formaldehyde (F) and melamine (M) as carbon precursors while collidal silica as hard template. The relationship between electrochemical performance of PMF series samples and M/P molar ratio were investigated in three electrolytes. The total nitrogen content could be tuned in a wide range of0-12wt.%by changing the initial molar ratio of melamine to phenol (M/P) in the precursors.Nitrogen functional groups exhibited asymmetric capacitance behaviors in KOH, H2SO4and organic electrolytes. Nitrogen functional groups had much higher contribution to the capacitance of the negative electrode than the positive one in KOH electrolyte. The nitrogen content (mainly pyridinic N, pyrrolic N) decreased when the pyrolysis temperatures increased from700℃to1000℃while the opposite trend for the graphitic N was observed. The M/P ratio only changed the total nitrogen content, while the increasing of pyrolysis temperature had a significant effect on the nitrogen species in PMF samples and caused the decrease of gravimetric capacitance of samples in three electrolyte systems.