Porous graphitic activated carbon sheets upcycled from starch-based packing peanuts for applications in ultracapacitors

Porous graphitic activated carbon made from biodegradable starch-based packing peanuts contain metallic impurities, such as sodium and potassium impurities. The metallic impurities are not only eliminated in the activation process and revelation. These carbon sheets appear to form an ultrathin graphitic layer on the surface of the disordered carbon framework of the packed peanut-derived activated carbon. The shell-like graphitic structure can be explained by potassium penetration into the carbon structure during chemical activation and subsequent catalytic graphitization by the metallic impurities. These graphitic structures produce high-power density properties. As sodium impurities are present in the depth of the PP-C, it is possible to synergize the effects of potassium. The combination of these structural properties enables the carbon sheets to provide a harmonious electrochemical environment for the full realization of fast ion transport and high capacitance. (C) 2019 Elsevier B.V. All rights reserved.