Preparation and optimization of nitrogen-doped porous carbon derived from bio-oil distillation residue for high-performance supercapacitors

A novel technique for the high-value utilization of bio-oil distillation residue (BDR) was proposed to prepare nitrogen-doped carbon materials for supercapacitors. BDR was activated with KOH as the activator and mel-amine as the nitrogen source by the orthogonal experimental method. The effects of KOH-to-BDR (K/B) ratio, melamine-to-BDR (M/B) ratio, and activation temperature (Tat) on the physicochemical and electrochemical characteristics of activated BDR (BAC) were systematically examined. The results showed that all the three factors had great impacts on the capacitance performance of BAC, in the order of K/B ratio > M/B ratio > Tat. The highest specific capacitance of BAC was 442.0 F/g at 1 A/g in a three-electrode system, and the corre-sponding preparation conditions were K/B ratio of 6.0, M/B ratio of 1.0 and Tat of 600 degrees C. Meanwhile, its energy density could reach 14.8 Wh/kg at 48.5 W/kg in a two-electrode configuration. The addition of melamine could optimize the composition and structure of BAC by increasing the nitrogen content and enlarging the pore size appropriately, which was instrumental in increasing the wettability and decreasing the transfer resistance of electrolyte into BAC.