E. grandis as a Biocarbons Precursor for Supercapacitor Electrode Application

Abstract

Wood residues are ordinary wastes in the forestry industry and their valorization is an important issue. Eucalyptus grandis wood dust was chosen as a model wood residue and biocarbons (BCs) and activated BCs were prepared from it and studied as active materials for supercapacitor electrodes. Several ordinary activation methods were used and microporous activated BCs with specific surface areas up to 900 m2 g−1, and different content of oxygenated surface groups were obtained. The preparation or activation temperature is the parameter that mainly affects the electrical conductivity. For temperatures above 700 °C, the samples reach an electrical conductivity as high as 1 S cm−1. The specific capacitance of the activated BCs reaches values up to 203 F g−1 in acidic electrolyte. The highest specific capacitance is obtained when chemical activation with ZnCl2 at 900 °C followed by chemical oxidation with nitric acid is used. BCs activated with ZnCl2 at 900 °C and CO2 at 800 °C displayed good rate capability and the maximum power density. Activation with ZnCl2 at 900 °C also leads to BCs with the maximum energy density. These results show that E. grandis wood dust is a promising low cost and environmental friendly precursor for biocarbon electrodes.