Effects of Biochar Electrode Structure, Dimension, and Surface Properties on Electrochemical Double-Layer Capacitor Performance by Daniel Alexander Yanchus A thesis submitted in conformity with the requirements for the degree of Master of Applied Science Department of Chemical Engineering and Applied Chemistry University of Toronto Copyright by Daniel Alexander Yanchus 2017
ii Effects of Biochar Electrode Structure, Dimension, and Surface Properties on Electrochemical Double-Layer Capacitor Performance Daniel Alexander Yanchus Master of Applied Science Department of Chemical Engineering and Applied Chemistry University of Toronto 2017 Abstract Supercapacitors, or electrochemical double-layer capacitors (EDLCs), are high power density storage devices that are able to complement or replace conventional batteries in niche energy storage situations. This thesis investigates the characterization and performance of monolithic biochar, produced from woody-biomass precursors, as an alternative supercapacitor electrode material in three parts. First, the electron deceleration scanning electron microscope technique is applied to biochar specimens, enabling the clear resolution of nanoscale surface features and their locations within the biomass precursor. Second, monolithic biochar electrodes are compared to their powder thin film structured counterparts, demonstrating equivalent device specific capacitance performances while electrode thickness increases up to 5 mm. Third, the influence of pyrolysis conditions on electrochemical performance is explored, revealing that while increasing the temperature improves conductivity and microporosity development, capacitive storage is hindered. Although capacitive performance appears relatively low, monolithic biochar’s unique structure and associated capabilities afford future opportunities as an electrode material.