Synthesis and electrochemical properties of nickel oxide coated ZnMn2O4 nanocomposites

Abstract

Nickel oxide coated ZnMn2O4 nanocomposites were successfully synthesized by two-step method combined hydrothermal reaction and calcination process. The microstructure, morphology and the color mapping of the as-prepared samples were characterized by means of X-ray diffraction, high resolution electronic microscope microstructure, field emission scanning electron microscopy and energy-dispersive X-ray spectrum. The electrochemical performance of the samples were investigated by cyclic volt-ampere (CV), constant-current chargedischarge and electrochemical impedance spectroscopy. The experimental results show that nickel oxide coated ZnMn2O4 nanocomposites exhibit weak Ni2O3 hexagonal phase besides obvious ZnMn2O4 spinel tetragonal structure, the morphologies are uniform polyhedron structure with obvious cladding layer. CV curves exhibit rectangular shape without obvious redox peaks. Nickel oxide coated ZnMn2O4 nanocomposites shows better specific capacitance and excellent cyclic stability, and maintains 98.8% of its initial capacitance after 1200 cycles. Nyquist plots of nickel oxide coated ZnMn2O4 nanocomposites proving the samples possess lower resistance and ideal electron conductivity.