Manganese oxide/MWNTs composite electrodes for supercapacitors

Manganese oxide/multiwalled carbon nanotubes (MWNTs) composite was prepared by mixing manganese oxide and MWNTs through a means of ultrasonic vibration in ethanol solution. A nonaqueous hybrid supercapacitor using manganese oxide/MWNTs (M/M) composite and MWNTs as positive and negative electrodes, respectively, has been designed and investigated by constant current charge/discharge tests. The asymmetric hybrid capacitor has better capacitance and energy characteristics than those of the symmetric ones based on individual M/M composite and MWNTs electrodes. The energy density of the hybrid capacitor can reach 32.91 W h/kg even at a current density of 10 mA/cm2 in 1.0 M LiClO4 electrolyte, which is comparable to that of a manganese oxide/activated carbon hybrid capacitor.