Synthesis and Characterization of Manganese Molybdate for Symmetric Capacitor Applications

A simple, one-step facile approach (precipitation technique) was employed to prepare manganese molybdate (α-MnMoO4). The obtained powder was characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and scanning electron microscopy (SEM) for analyzing structural, functional group and morphological features. The formation of α phase MnMoO4 particles was identified from XRD. The SEM results showed rhombohedral morphology of the particles. The capacitive behavior was investigated by cyclic voltammetry (CV), charge-discharge (CD) cycling and electrochemical impedance spectroscopy (EIS) studies using 2 M NaOH electrolyte at ambient atmosphere. From the cyclic voltammogram it was identified that the pseudocapacitance arises through the reversible faradic reactions of Mn3+/Mn2+ ionic species. The α-MnMoO4 electrode exhibited a capacitance of 200 F/g at a constant discharge current density of 1.6 A/g. The α-MnMoO4 vs. α-MnMoO4 symmetric supercapacitor device was fabricated and it delivered a maximum specific capacitance (81 F/g) with a specific energy density of 11 Wh/kg. The cycle life tests showed stable electrochemical performance up to 200 cycles with well rated cycle life and 1000 cycles providing 91 % of specific capacitance. The obtained values showed superior electrochemical performance than oxide counterparts.