Study On The Preparation Of High Specific Capacity Nb,Sb,V Metal Oxides And Their Supercapacitor Performance

The disadvantage of supercapacitors is low energy density.In application,supercapacitors are often used in series with each other,which leads to the problem of occupying too much space.Therefore,only by increasing its energy density can its expand the application market.The pseudocapacitor has begun to came into people's view,it has higher energy density than the electric double layer capacitors,and has high power density and long cycle life and broad application prespects.Metal oxide is the main electrode material of pseudocapacitor,which is the research content of this work.In this work,the metal oxides of Nb,Sb and V have been studied,porous spherical Nb₂O₅,air filter-like structure Nb₂O₅,flower-like structure Sb₂O₃and high capacity VO₂was prepared by solution method,hydrothermal method and calcaination method.The morphologies and microstructures were investigated by X-ray diffractometer,scanning electron microscopy and transmission electron microscopy.The electrochemical properties of the materials were obtained by electrochemical test.The relationship between the structural morphology and electrochemical properties of the materials was analyzed and discussed.Then the experimental scheme was improved to further improve the performance of the super capacitor.The results show that all the four materials have excellent supercapacitor performance,among which porous spherical Nb₂O₅,air filter-like structure Nb₂O₅,flower-like structure Sb₂O₃have unique microstructure characteristics.After calcination,spherical Nb₂O₅is transformed into porous spherical Nb₂O₅,which shows abundant holes and channels in the interior,and its electrochemical performance is further improved.The porous spherical Nb₂O₅deliver the specific capacitance of 351 F g^-1at a current density of 0.5 A g^-1,and good cyclic stability of 92%capacitance retention after 3000 cycles.The surface of air filter-like structure Nb₂O₅has crisscross"fence",control experiment shows that urea is the key factor to form the structure.The air filter-like structure Nb₂O₅with 205 m²g^-1high specific surface area,deliver the specific capacitance of 258 F g^-1at a current density of 0.5 A g^-1,and good cyclic stability of 90.5%capacitance retention after 5000 cycles.There are many"flowers"on the surface of flower-like structure Sb₂O₃,and the water bath temperature is the decisive factor for the formation of the morphology.The flower-like structure Sb₂O₃at 30?water bath temperature deliver the specific capacitance of 580 F g^-1at a current density of 0.5 A g^-1,and good cyclic stability of 91.6%capacitance retention after 2000 cycles.In the process of preparing high capacity VO₂,the effects of the molar ratio of vanadium to carbon,calcination temperature and calcination time on the experiment were investigated systematically.Under the optimal experimental conditions,VO₂has excellent supercapacitor performance,it deliver the specific capacitance of 388 F g^-1at a current density of 2 A g^-1,and good cyclic stability of87.1%capacitance retention after 3000 cycles.