Preparation And Capacitance Performance Of Mn/V Composite Oxide

Manganese-based composite oxide has attracted extensive attention,which is because it not only has natural abundance,low cost and environmentally friendly, but also has ideal pseudocapacitance behavior.Preparation methods, molar ratio and temperature ,which have affect on the properties of composite oxide,were discussed in this paper.The physical and chemical properties of samples were characterized by X-ray diffraction (XRD),X-ray photoelectron spectroscopy (XPS),scanning electron microscopy (SEM) etc.When the initial molar ratio of KMnO4 to MnSO₄ was 2:3,the electrochemical properties of composite oxide was researched with the different molar of MnO₂ to V₂O₅.The experimental results show that in 0.5 mol·L-1Na2SO4 aqueous electrolyte Mn/V composite oxide whose inner and outer specific capacitance reached 292.40 F·g^-1 and 136.33 F·g^-1 exhibited the excellent electrochemical properties within the range of -0.1 0.9V(vs.SCE).In addition,the specific capacitance of composite oxide is up to 210 F·g^-1 at the discharge current density of 1 A·g^-1 ,which is larger than that of MnO₂ electrode to 170 F·g^-1.The results of cycle life showed the specific capacitance of Mn/V composite oxide electrode faded quickly with cycle numbers,but the specific capacitance of MnO₂ electrode was almost unchanged and showed good stability.When the initial molar ratio of KMnO4 to MnSO₄ was 4:3,the electrochemical properties of composite oxide was discussed by the different molar of MnO₂ to V₂O₅. MnO₂ and V₂O₅ with the molar ratios of 10:1,the inner and outer specific capacitance of Mn/V composite electrode was 240.00 F·g^-1and 147.66 F·g^-1; at the discharge current density of 1 A·g^-1, the specific capacitance of composite oxide reached 205 F·g^-1, which is larger than the capacity of MnO₂ electrode.Cycle life test showed that the specific capacitance of composite oxide Mn/V reduced with the rapid decay of cycles.On the contrary, the specific capacitance of MnO₂ decayed slowly with the cycle numbers.When the initial molar ratio of KMnO4 to MnSO₄ was 4:1,the electrochemical properties of composite oxide was studied with the different molar of MnO₂ to V₂O₅.MnO₂ and V₂O₅ with the molar ratios of 25:1,the inner and outer specific capacitance of Mn/V composite electrode was 231.48 F·g^-1 and 164.74 F·g^-1.At the discharge current density of 1 A·g^-1, the specific capacitance of composite oxide is up to 208 F·g^-1, which is larger than the capacity of MnO₂ electrode.The composite oxide was prepared by sodium metavanadate,the electrochemical properties of composite oxide was studied with the different molar of MnO₂ to V₂O₅.MnO₂ and V₂O₅ with the molar ratios of 15:1,the inner and outer specific capacitance of Mn / V composite electrode was 218.41 F·g^-1and 141.78 F·g^-1.At the discharge current density of 1 A·g^-1, the specific capacitance of composite oxide got to 207 F·g^-1, which is larger than the capacity of MnO₂ electrode.Mn/V composite oxide was prepared by liquid phase precipitation method at room temperature with potassium permanganate, manganese sulfate and ammonium metavanadate.The electrochemical properties of composite oxide was discussed by pre-treatment temperature.MnO₂ and V5O12 with the molar ratios of 20:1 and the pre-treatment temperature 200℃,the inner and outer specific capacitance of Mn / V composite electrode was up to 223.21 F·g^-1,161.54 F·g^-1.At the discharge current density of 1 A·g^-1, the specific capacitance of composite oxide got to 196 F·g^-1.