Corn Stover-Derived Biocarbon from Hydrothermal Liquefaction for Supercapacitor Applications

Biocarbon for supercapacitor anodes has become a frontrunner for renewable energy storage materials. Its unique physical characteristics allow for enhanced rate capabilities, increased ion transport, all leading to sustainable scale-up. Current work focuses on the use carbon-rich residue from the corn stover refining. Value added chemicals were first extracted by enzymatic hydrolysis, and the resultant lignin-rich unhydrolyzed solids (UHS) derived from preprocessing of corn stover were subjected to hydrothermal liquefaction (HTL). Bio-char samples derived from investigating the HTL reaction kinetics at various temperatures, initial purge, reaction time, and biomass loading, were subjected to thermal treatment at 400 °C under nitrogen for 2 h and followed by the activation at 850 °C under Ar for 3 h to obtain the biocarbon material. Electrochemical results show that select samples reach capacitances above 200 F g^-1 at 5 mV s^-1. Physical and electrochemical characterizations such as BET, XRD, SEM, and ATR-FTIR, Raman, cyclic voltammetry, and chronopotentiometry were carried out to fundamentally probe the biocarbon. This work provides an insight into how pretreatment conditions affects the performance of biocarbon for supercapacitor applications.