Supercapacitor performance of corn stover-derived biocarbon produced from the solid co-products of a hydrothermal liquefaction process

Abstract Biocarbon is obtained by the graphitization of biochar, a co-product in a novel integrated biorefinery concept that simultaneously produces C1–C3 acids, phenol, bio-oil, and biochar. The unhydrolyzed solids from the IBR are hydrothermally liquefied to obtain bio-oil and biochar coproducts. The biochar samples obtained from the HTL of UHS at different process conditions were low temperature thermally treated to remove volatile compounds, followed by a facile high temperature graphitization to biocarbon. Physical analyses showed the degree of graphitization directly effects pore volume. The UHS-SDC9 biochar produced at 275 °C, 40 psig, and 1 h of hydrothermal treatment exhibited the biocarbon with the best electrochemical performance having specific capacitance of 242 F g−1 at a scan rate of 5 mV s−1 and an energy density of 9.9 W h kg−1. Statistical analysis was performed to correlate the IBR processing parameters to physical and electrochemical characteristics of the biocarbon obtained.