Abstract
This communication discusses the criteria for appointing the highest acceptable cell voltage of asymmetric supercapacitors. An electrochemical capacitor (EC) consisting of graphene anode and activated Mn 3 O 4 cathode is employed as the model system. The capacitive performances of this asymmetric EC are evaluated by cyclic voltammetric, charge/discharge and electrochemical impedance spectroscopic (EIS) analyses. The criteria for appointing the highest appropriate cell voltage of asymmetric ECs with excellent reversibility and capacitor-like behaviour are proposed. © 2012 Elsevier B.V. All rights reserved.