Preparation of Scallion-Derived Porous Carbon with Regular Pore Structure for High-Performance Supercapacitors

Abstract

On the premise of ensuring high specific surface area, further improving the pore structure of biomass-based activated carbon is highly desired for supercapacitors applications. And the properties of many biomass-based activated carbons need to be improved by further optimizing the preparation process. Herein, the scallions were used as raw materials to prepare activated carbon electrode materials via activation with KOH or synchronous activation and graphitization with K2FeO4 for supercapacitors in this study. Based on the large specific surface area (3298.76 m2 g−1) and outstanding hierarchical porous structure, the final product presented a high capacitance of 381.51 F g−1 at a current density of 1 A g−1 and a prominent energy density of 54.3 W h kg−1 at the power density of 179.33 W kg−1. Besides, it also exhibited a low equivalent series resistance (0.27 Ω). When K2FeO4 was used as the activator, the samples exhibited a better rate performance (77.8% at a current density of 10 A g−1) and a long cycle stability (98.9% retention after 5000 cycles at 5 A g−1). Hence, the scallion-based activated carbon is a perspectives material for clean energy storage/conversion and this synchronous strategy provide a guideline for a much-simplified and green manufacture process.