Synthesis And Properties Of Manganese Base Electrode Materials For Supercapacitors

Supercapacitors have attracted more attentions for the superior power density,good cycle stability,and environmental friendliness.As ordered porous materials,metal-organic frameworks?MOF?have many applications due to their high specific surface area,permanent porosity and tunable pore sizes.and many kinds of carbon materials,metal oxides materials,and carbon/metal oxides materials ave been prepared by using MOFs as precursors.In this paper,Mn-MOF?Mn-MIL-100?was prepared by solvothermal method,as a result,manganese oxides and MnO@C materials were prepared.The microstructure and morphology of the cathode materials were characterized by X-ray diffraction,transmission electron microscopy,scanning electron microscope,X-ray photoelectron spectroscopy.Electrochemical properties were tested by galvanostatic charge/discharge,cyclic voltammetry and electrochemical impedance spectroscopy.Mn-MIL-100 prepared by solvothermal method presents regular octahedron with a side length of about 800 nm.The Mn-MIL-100 presents a typical pore structure with a high specific surface area of about 507 m² g^-1 and a high pore volume of 0.531 cm³ g^-1with pore size distributed in 0.5-20 nm.The Mn-MIL-100 was used as precursor to prepare high-valence manganese oxides in a muffle furnace at 400?,500?and 600?.Mn₃O₄ havre been prepared by calcining at 600?,which shows high specific capacity(180F g^-1)and excellent cycling stability of 89%after 5000 cycles.MnO@C materials have been prepared by calcining under nitrogen protection indicating a regular octahedron with a side length of about 500 nm,which was far more smaller than that of Mn-MIL-100 precursor?800 nm?.The MnO@C materials prepared present a high specific surface area of about 256 m² g^-1 with a high pore volume of 0.233cm³ g^-1.MnO@C materials combines the characteristics of double layer capacitors and tantalum capacitors,which greatly improves the specific capacity,and cycle stability.The high specific capacity can reach 421?359?324 and 270 F g^-1 at the current density at0.5,1.0,2.0 and 5.0 A g^-1 with superior cycle stability of 91%after 5,000 cycles at a current density of 5A g^-1.