Microwave-assisted synthesis of novel 3D flower-like NiMnO3 nanoballs as electrode material for high-performance supercapacitors

Abstract

In order to improve the electrochemical performance of supercapacitors, a novel 3D flower-like NiMnO3 nanoballs electrode material were prepared by microwave-assisted hydrothermal methods at different deposition temperature. The crystal phase, chemical valence states and function groups of the as-prepared material were analyzed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Bruker transform infrared spectra (FT-IR). The Field-emission scanning electron microscopy (SEM), transmission electron microscope (TEM) and Brunauer-Emmett-Teller (BET) were reveals sample's morphology and the surface area. Its electrochemical performance was evaluated by traditional three-electrode system in 6 mol/L KOH solution. The results indicated that the morphology of NiMnO3 electrode material changed from nanobulks to flower-like nanoballs with temperature increasing. The optimal temperature was 160 °C. At this point, the specific capacitance reached 345.8 F g−1 at 1 A g−1. The specific capacitance retention maintained about 92% after 1000 cycles at 3 A g−1. Owing to flower-like structure, which not only increased the surface area but also added the electrolyte ion transfer channels, that contributed to increasing the electrochemical properties. The good cycle stability and the high specific capacity, lead to NiMnO3 become a promising candidate for the next generation supercapacitor electrode material.