Preparation and Electrochemical Properties of Modified Biochar

High-performance biochar-based supercapacitors extremely depend on the reasonable microstructure of electrode materials, so optimizing pore structure and surface properties is an important research topic. In this paper, HNO3 and H2O2 were used to modify wood chip biochar, which enhanced the oxygen-containing functional groups of biochar and optimized the pore size distribution. NPCBC-45 and HPCBC-20 micropore sizes were concentrated at 0.92 nm and 0.90 nm, respectively, and the mesoporosity was 33 % and 65 %, respectively. The supercapacitors using NPCBC-45 and HPCBC-20 as electrodes exhibited excellent specific capacitance, reaching 338.88 F center dot g- 1 and 165 F center dot g- 1, respectively, which were increased by 137.39 % and 15.59 %, respectively. The prepared double-layer capacitor showed good cycle stability, and the cycle efficiency was 94 % after 2000 cycles. Therefore, the results of this study show that HNO3 and H2O2 have application value in optimizing the microstructure of carbon material electrodes.