Facile electrochemical oxidation of activated carbon at low voltage for supercapacitors

摘要

The rehmannia glutionosa activated carbon prepared by carbonization and activation exhibits a porous structure with a specific surface area of 1722.84 m(2) g(-1). Furthermore, a low voltage electrochemical oxidation method is employed to modify this active carbon. By this way, the capacitance and energy density of the modified rehmannia glutionosa activated carbon is increased by 20.5% (from 161F g(-1) to 194F g(-1)) and 24.9% (from 3.78 Wh kg(-1) to 4.72 Wh kg(-1)), respectively. The capacity retention rate keeps 88.3% even cycling 5000 times at 5A g(-1). The result shows that the rehmannia glutionosa activated carbon is more appropriate as negative electrode while the electro-oxidized rehmannia glutionosa activated carbon can be used as either positive electrode or negative electrode. This paper proposes a practical idea of the electrochemical oxidation for the materials that are not resistant to high voltage. (C) 2021 Published by Elsevier B.V.