A novel hydrothermal synthesis and characterisation of porous Mn3O4 for supercapacitors with high rate capability

Abstract

Porous nanostructured Mn₃O₄ particles were successfully synthesized by a novel hydrothermal method via adding the surfactant hexadecyltrimethylammonium bromide (CTAB). They were characterized by the techniques of thermogravimetric and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N₂-adsorption. The electrochemical performance of the sample was studied by galvanostatic charge–discharge, cyclic voltammetry and electrochemical impedance spectroscopy in 1 M Na₂SO₄ aqueous solution electrolyte. It exhibits a high specific capacitance (232.5 F g⁻¹ at 0.5 A g⁻¹) and good rate capability (190 F g⁻¹ at 5 A g⁻¹), which can be attributed to its porous structure, the defects and vacancies on the surface. The capacitance retention reaches 78% after 5000 cycles at a current density of 5 A g⁻¹. The results show that Mn₃O₄ has the potential to be used as the electrode material for a supercapacitor with high performance.