Mixed valence nanostructured Mn3O4 for supercapacitor applications

Abstract

Nanostructured Mn3O4 with an average crystallite size of ∼19 nm was synthesized through a microwave-assisted chemical route. Structural characterization was carried out using X-ray diffraction analysis and transmission electron microscopy. Observed change in the ratio of lattice constants, c/a for the sample compared with single-crystalline Mn3O4 points to the presence of Mn4+ ions at the octahedral sites. This is attributed to the presence of cation vacancies. X-ray photoelectron spectroscopic studies confirm the presence of Mn4+ ions. Specific capacitance value of 665.08 F g-1 was obtained for symmetric supercapacitor with Mn3O4 active material at slow scan rate. Reasonably high power and energy density values, viz., 4.27 kW kg-1 and 4.36 × 10-2 Wh kg-1, respectively, were obtained for charge-discharge cycles at a constant current of 12.74 mA cm-2.