Study of electrochemical properties and the charge/discharge mechanism for Li4Mn5O12/MnO2-AC hybrid supercapacitor

Spinel Li 4 Mn 5 O 12 was prepared by a sol–gel method. The manganese oxide and activated carbon composite ( MnO 2 -AC) were prepared by a method in which KMnO 4 was reduced by activated carbon (AC). The products were characterized by XRD and FTIR. The hybrid supercapacitor was fabricated with Li 4 Mn 5 O 12 and MnO 2 -AC, which were used as materials of the two electrodes. The pseudocapacitance performance of the Li 4 Mn 5 O 12 /MnO 2 -AC hybrid supercapacitor was studied in various aqueous electrolytes. Electrochemical properties of the Li 4 Mn 5 O 12 /MnO 2 -AC hybrid supercapacitor were studied by using cyclic voltammetry, electrochemical impedance measurement, and galvanostatic charge/discharge tests. The results show that the hybrid supercapacitor has electrochemical capacitance performance. The charge/discharge test showed that the specific capacitance of 51.3 F g −1 was obtained within potential range of 0–1.3 V at a charge/discharge current density of 100 mA g −1 in 1 mol L −1 Li 2 SO 4 solution. The charge/discharge mechanism of Li 4 Mn 5 O 12 and MnO 2 -AC was discussed.