Bio-Derived Nanocarbons in Electrochemical Applications

Abstract

Carbonaceous materials are well known and readily used in a broad range of applications. Owing to the well-developed porous structure and the presence of certain surface functional groups, these materials are commonly used as adsorbents for a wide range of contaminants from gaseous or liquids media. Currently, activated carbons are also widely used as the electrodes for electric double-layer capacitors because of their high surface area, chemical stability and acceptable price.This work is focused on the carbon materials obtained from biopolymers such as lignin, cellulose and chitosan as precursors. The carbonisation in nitrogen atmosphere followed by chemical activation in KOH was chosen as a synthesis method. The resulting carbon materials were characterised by well-developed surface area and microporous structure, beneficial for electric double-layer capacitors (EDLC) electrodes. In parallel, graphene-like materials obtained from graphite oxidation followed by thermal reduction were also synthesised.The main goal of performed research tasks was to compare the electrochemical properties of carbon materials applied as electrode materials in different energy storage systems - electrochemical capacitors and in hydrogen storage systems. The special example taken into the consideration were hybrid capacitors composed of a battery-type electrode and a high surface area carbon electrode. This kind of configuration allows merging the advantages and reduces the drawback of redox and capacitive based systems. Since the same electrode material can give different electrochemical response depending on the type of device in which they are employed, this work will report on the influence of the physicochemical properties of carbon-based electrodes of various origin on their electrochemical response in various energy storage systems.