A novel hybrid manganese dioxide/activated carbon supercapacitor using lithium hydroxide electrolyte

We present here a novel hybrid nano-structured manganese dioxide/activated carbon supercapacitor with lithium hydroxide electrolyte, in which the MnO2 positive material was prepared using a solid-state reaction route. The electrochemical behaviors of MnO2 electrodes in 1 M LiOH and 1 M KOH electrolytes, respectively, were characterized by cyclic voltammetry and electrochemical impedance spectroscopy methods. The results indicated that the reaction mechanism of MnO2 electrode in LiOH electrolyte appears to be Li+ ion insertion/extraction in MnO2 solid, which is different with that electrode in KOH electrolyte. Charge/discharge experiments showed that the rate dischargeability of the MnO2/AC capacitor with 1 M LiOH electrolyte is excellent, and the cyclic stability of the MnO2/AC capacitor with 1 M LiOH electrolyte is much better than that with 1 M KOH electrolyte. (C) 2006 Elsevier B.V. All rights reserved.