Bio-Based Carbon Materials from Potato Waste as Electrode Materials in Supercapacitors

This study investigates the production of biobased carbon materials from potato waste and its application in energy storage systems such as supercapacitors. Three different categories of carbons were produced: hydrochar (HC) from hydrothermal carbonization (HTC) at three different temperatures (200 degrees C, 220 degrees C, 240 degrees C) and two different duration times (two hours and five hours), pyrolyzed hydrochar (PHC) obtained via pyrolysis of the HTC chars at 600 degrees C and 900 degrees C for two hours and pyrochar from the pyrolysis of biomass at 600 degrees C and 900 degrees C for two hours. The carbon samples were analysed regarding their physico-chemical properties such as elemental composition, specific surface area, bulk density and surface functionalities as well as their electrochemical characteristics such as electric conductivity and specific capacity via cyclic voltammetry. N- and O-enriched carbon materials with promising specific surface areas of up to 330 m(2) g(-1) containing high shares of microporosity were produced. Electric conductivities of up to 203 S m(-1) and specific capacities of up to 134 F g(-1) were obtained. The presence of high contents of oxygen (4.9-13.5 wt.%) and nitrogen (3.4-4.0 wt.%) of PHCs is assumed to lead to considerable pseudocapacitive effects and favor the high specific capacities measured. These results lead to the conclusion that the potential of agricultural biomass can be exploited by using hydrothermal and thermochemical conversion technologies to create N- and O-rich carbon materials with tailored properties for the application in supercapacitors.