The Synthesis And Electrochemical Performance Of Porous Trimanganese Tetraoxide Electrode Materials

Due to its higher capacitance, low-costs, and environmental-friendly, trimanganese tetraoxide（Mn₃O₄） electrode materials have attracted signicant attention. In this paper,Mn₃O₄ with porous structure has been successfully prepared by a solvothermal approach.Effects of surfactant on microstructure and electrochemical performances of Mn₃O₄ electrode materials have been investigated using X-ray diffraction（XRD）, scanning electron microscopy（SEM）, electrochemical impedance spectroscopy（EIS） and cyclic voltammetry（CV） measurements.The microstructure of Mn₃O₄ electrode materials were examined. The results show that the Mn₃O₄ electrode materials using hexadecyltrimethylammonium bromide（CTAB）as a surfactant have the crystal structure of tetragonal crystal system spinel structure with space group of I41/amd. The Mn₃O₄ presents a three dimensional structure of cauliflower morphology, which is self-assembled by two-dimensional lamella structure with a thickness of approximately 100 nm. The result of BET test reveals that the manganese oxide electrode materials has typical mesoporous material characteristics with a specific surfactant area of 138.5 m2 g-1 and the pore-size around 10 nm. The electrochemical tests indicates that the specific capacitance of the Mn₃O₄ electrode materials is 302 F g-1 at the current density of 0.5 A g-1, and the capacitance rention is 90 % after 5000 cycles at the current of 5 A g-1. The results of electrochemical impedance spectroscopy test show that the charge transfer resistance is 0.52 Ω.The Mn₃O₄ electrode materials with spongy porous nano-structure（50 nm） were prepared by using CTAB and sodium dodecyl sulfate（SDS） as the co-surfactant（1:1）.Electrochemical tests indicate that the specific capacitance of the Mn₃O₄ electrode materials with the spongy porous structure is as high as 451 F g-1 at the current density of0.5 A g-1 in 1 M sodium sulfate electrolyte. The specific capacitance is increased by about49 % than that of the trimanganese tetraoxide electrode material（302 F g-1） at the current of 0.5 A g-1. And the capacitance retention is 91.9 % after 10000 cycles at a current density of 5 A g-1. The result of electrochemical impedance spectroscopy test shows thatthe charge transfer resistance is 0.21 Ω, and the charge transfer resistance is decreased by59.7 % than that of the cauliflower trimanganese tetraoxide（0.52 Ω）.