Study On The Preparation, Characterization And Performance Of Metal Nitrides For Supercapacitors

Based on detailed investigation of a great deal of related literatures, the preparation, characterization and the electrochemical performance ofγ-Mo2N and VN for supercapacitor were studied.γ-Mo₂N and VN were prepared by gas-solid reaction. The nanostructures of the materials were effectively modulated by sol-gel method and controlling heating rate, and the grain like, petal like and coral reef like nitrides electrode materials.The influences of the heating rate, reaction temperature, sorts and concentration of electrolytes on the specific capacitance were exploring analyzed. MoO₃ and V₂O₅ xerogel was prepared by sol-gel method, and then the xerogel precursor was nitrided. The specific capacitance of the product increased greatly. C/V compounded material was obtained by addion of PEG2000, the impact of temperature and dispersant on the capacitive performance of the products were both investigated, and high specific capacitance was gained.The products were characterized by X-ray diffraction, scanning electron microscopy and transition electron microscopy. And the supercapacitive performance was tested by cyclic votammetry, chronopotentiometry, and A.C.Impedance.Theγ-Mo₂N electrode prepared by gas-solid reaction showed good supercapacitive behaviors. At a scan rate of 1 mV/s, the specific capacitance reached 172 F/g, and the potential window was broadened 0.3 V. The xerogel, which was prepared from MoO₃ and H₂O₂, was nitrided then the morphology and specific capacitance of the product were improved significantly. The sample showed a petal like structure and owned a high specific capacitance of 271 F/g. The specific capacitance increased obviously with a rate of 40% after activation of HCl solution. The samples possess good electrochemical stability.The as-prepared VN electrode also had good supercapacitive behaviors. At a scan rate of 2 mV/s, the specific capacitance of the gas-solid product reached 128 F/g. The V₂O₃/C composite material prepared from addition of PEG2000 showed good supercapacitive behaviors. The sample was activated by KOH, and the specific capacitance of the sample was enlarged remarkably when activated under N2 atmosphere. The results of XRD showed that the composition of the produce changed after activation. The loss of the capacitance of all the as-prepared materials was less than 10%.