A new asymmetric supercapacitor based on λ-MnO 2 and activated carbon electrodes

Abstract

Lithium-ion intercalated compound λ-MnO 2 was used as positive electrode in asymmetric supercapacitor with activated carbon used as negative electrode in 1 mol L − 1 Li 2SO 4 aqueous electrolyte solution. Phase composition, morphology and particle sizes of λ-MnO 2 were studied by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). Electrochemical capacitive performance of the asymmetric supercapacitor was tested by cyclic voltammetry 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 . It is obvious that λ-MnO 2 is a potential electrode material for asymmetric supercapacitor.