Electrochemical performance of α-MnO ₂ nanorods/activated carbon hybrid supercapacitor

Hollondite type α-MnO ₂ nanorods are prepared by hydrothermal route at 160 °C for 8 h. The structural and morphological properties are examined by X-ray diffraction, BET surface area, scanning electron microscopy and high resolution transmission electron microscopy. Half-cells (Li/α-MnO ₂) are fabricated to study the Li-cycling behavior in both galvanostaic and potentiostatic modes. The α-MnO ₂ delivers a stable reversible capacity of ~80 mA h g-1 at constant current 50 mA g-1 up to 50 cycles when cycled between 1.5-3.8 V versus Li. The hybrid electrochemical capacitor is fabricated using α-MnO ₂ nanorods (as anode) and activated carbon (as cathode) in non-aqueous medium and cycled between 0-3 V. The hybrid electrochemical capacitor exhibited a stable specific discharge capacitance of 28 F g-1 at high current (60 mA g-1). Further, hybrid electrochemical capacitor displayed a maximum energy and power densities of 9 W h kg-1 and 87 W kg-1, respectively.