Study On Preparation And Electrochemical Performance Of V Based Electrode Materials For Supercapacitor

Supercapacitor?also called electrochemical capacitor?,which are considered as a promising candidate to power the next generation of energy storage device,havebeen widely investigated to meet the increasing requirements owing to their high power density,long cyclic stability and rapid charge/discharge rate.Undoubtedly,the properties of the electrode materials are the key factors to determine the performance of the supercapacitors.This means that the electrode should not only have the features of simple synthesis and environmental friendly character,but also possess high electrochemical capability.Supercapacitor electrode materials mainly include carbon materials,metal compounds,and polymer conductive polymers.However,single material cannot meet the requirements of practical application due to the intrinsic defects.Therefore,the design of composite electrode materials has become a hot spot in the research field of supercapacitors.The synergistic effect of different materials can effectively improve the electrochemical performance of electrode materials.Therefore in this thesis,two kinds of transition metal compounds?V₂O₃,VC?electrode materials were synthesized.In order to improve the capacitance performance of the material,the two kinds of compound particles were further loaded onto the mesoporous carbon?MC?carrier,and the composite electrode material of mesoporous carbon supported vanadium oxide?V₂O₃@MC?and mesoporous carbon supported vanadium carbide?VC@MC?were synthesized.The microstructure and morphologies were investigated by X-ray diffraction spectroscopy?XRD?,scanning electron microscopy?SEM?,transmission electron microscopy?TEM?,N₂ sorption isotherm and so on.In addition,the electrochemical performances of the as-prepared materials have been examined by cyclic voltammetry?CV?,galvanostatic charge-discharge?GCD?and electrochemical impedance spectra?EIS?.Electrochemical performance of vanadium oxide embedded in mesoporous carbon?V₂O₃@MC?composite electrode material.In the 1M Na₂SO₄ electrolyte,it turns out that V₂O₃@MC displays a higher specific capacity than the pure V₂O₃,reaching 354.9 F g^-11 and301.5 F g^-11 at current densities of 0.25 A g^-11 and 1.00 A g^-1,respectively.V₂O₃@MC has a retention rate of 97.6%after 1000 cycles,while the V₂O₃ capacity retention rate is only 26.5%.In the 1M H₂SO₄ electrolyte,the as-prepared V₂O₃@MC electrode shows a high specific capacitance of 189.2 F g^-1,which is about 59.2 F g^-11 higher than V₂O₃.After 1000 cycles,V₂O₃@MC exhibits a high capacitance retention rate?89.3%?,while V₂O₃ retention is only7.0%.Such desirable properties signify that the V₂O₃@MC composites can be a promising electrode material in the application of the supercapacitor.Electrochemical performance of vanadium carbide embedded in mesoporous carbon?VC@MC?composite electrode material.In the electrolyte solutions of 1M H₂SO_4,1M Na₂SO₄,1M KOH,the specific capacitance of the VC electrode material reaches 95.6,111.0and 74.4 F g^-11 respectively,at a current density of 1.00 A g^-1.VC@MC composite possesses large surface area with mesoporous structure,which can effectively accommodate the electrolyte ions migration and accelerate efficient electron transport.The specific capacity of the VC@MC electrode in the three electrolytes is as high as 191.2,169.8 and 150.4 F g^-1,respectively,and the capacity retention is 91.4%,87.4%and 87.5%after the cycle performance test.Therefore,the VC@MC composites are an ideal electrode material with excellent specific capacitance,rate capability and cyclic stability compared to single component.In conclusion,the prepared composite electrode material in this study exhibits better electrochemical performance than the single electrode material,enriching the research content of the supercapacitor electrode material,which shows that the synthetic supported composite material is an effective way to improve the electrochemical performance of the electrode.