A new asymmetric supercapacitor based on λ-MnO2 and activated carbon electrodes

Lithium-ion intercalated compound lambda-MnO2 was used as positive electrode in asymmetric supercapacitor with activated carbon used as negative electrode in 1 mol L-1 Li2SO4 aqueous electrolyte solution. Phase composition, morphology and particle sizes of lambda-MnO2 were studied by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). Electrochemical capacitive performance of the asymmetric supercapacitor was tested by cyclic voltarnmetry and galvanostatic charge-discharge tests. The results show that the asymmetric supercapacitor has electrochemical capacitance performance within wide potential range of 0-2.2 V. The specific capacitance is 53 F g(-1) at a constant current density of 10 mA cm(-2). The energy density is 36 W h kg(-1) with a power density of 314 W kg(-1) is obvious that X-MnC is a potential electrode material for asymmetric supercapacitor. (C) 2008 Elsevier B.V. All rights reserved.