Renewable energies have usually the problem that their supply is intermittent. They need energy storage systems (ESSs), that can capture energy at any time, store it and release it when it is necessary. Supercapacitors could be a good solution because of their long cycle-life, fast charging and discharging time and satisfactory values of energy and power densities. This thesis is focused on the study of a new, eco-friendly and cheap material for supercapacitor applications: biochar. It is a carbon-rich porous material obtained from pyrolysis of lignocellulosic biomass, in this case sugar maple wood. Biochar has always been used in agricultural systems to improve soil fertility.