Synthesis and characterization of nanostructured ternary zinc manganese oxide as novel supercapacitor material

Nanostructured ZnMn2O4 is prepared by easy and cost effective urea combustion method, and characterized by X-ray diffraction, field-emission scanning electron microscope, transmission electron microscope and surface area analyzer. The prepared ZnMn2O4 (ZMO) is found to be crystalline and mesoporous in nature with homogenously distributed pores. The supercapacitive properties of the synthesized materials are studied using cyclic voltammetry, galvanostatic charge discharge cycling and electrochemical impedance spectroscopy in 2 M KOH solution employing three-electrode system. The FESEM analysis reveals nearly spherical morphology of ZMO which is found to be beneficial for improved supercapacitive performance. Cyclic voltammetry shows unsymmetrical charge discharge curves with the capacitance value of 160 (+/- 5) Fg(-1). The galvanostatic charge discharge cycles exhibit good electrochemical stability of ZMO. The coulombic efficiency of ZMO is found to be almost 100% till 500 charge discharge cycles. The electrochemical impedance spectroscopy studies confirm the structural stability and further complement the findings of cyclic voltammetry and galvanostatic cycling. The improved supercapacitive behavior of nano ZMO is ascribed to the unique morphology that consists of interlinked almost spherical nano particles. This interlinked assembly of ZMO nano particles with porous structure (homogeneous pores 10-30 nm) probably facilitates the ion kinetics at electrode-electrolyte interface. (C) 2014 Elsevier B.V. All rights reserved.