Hundred Farad-scale Supercapacitor with Monolithic Biochar Electrodes – a Feasibility Study

Supercapacitors are high power density electrochemical storage devices that are hindered from widespread adoption by prohibitive material costs, low energy densities for practical applications, and poor scalability. This thesis seeks to solve all three issues by using large-scale monolithic maple-derived biochar as an effective electrode material. Biomass-derived carbon monoliths are pyrolyzed at 800oC and treated with 0.5M nitric acid at room temperature. Two electrode pairs, measuring ~5mm x 5mm x 5mm and ~23mm x 13mm x 10mm respectively, orders of magnitude thicker than typical supercapacitor electrodes, are tested using a suite of electrochemical techniques in 4M KOH electrolyte. Additional testing is done on large electrodes in 1M and 6M KOH, as well as in 1M TEA-TFB organic electrolyte. Capacitive performance of 107 F or 38.2 F/g is observed in the large monolithic electrodes, along with an exceptional energy density of 9.12 Wh/kg.%%%%M.A.S.