Preparation And Electrochemical Application Of Transition Metal Compound Composites

In recent years,because of the environmental pollution problem caused by the development of fossil fuels,and new energy storage devicese are urgently needed.As an important part of green and sustainable energy system,attracting more and more attention of scientists.Transition metal compounds are good candidates for preparing supercapacitors because of their advantages such as abundant reserves,low price,good stability and high energy density in nature.Introducing transition metal compounds into other carbon materials or other electrode materials with better electrical conductivity is expected to improve the electrical storage performance of transition metals.In this dissertation,Mn²⁺-doped nickel molybdate/mesoporous carbon composites were prepared,of which the component ratio was adjusted to show a better electrochemical performance as electrode material for supercapacitor.Then Ni-MOF/CNT_X composite materials were prepared by a hydrothermal method to combine Ni-MOF and CNT.Besides,MOF-derived Ni_xCo_1-x（OH）₂ material was also obtained via a hydrothermal method.The materials were analyzed by characterizations including X-ray diffraction,X-ray photoelectron spectroscopy,scanning electron microscopy and transmission electron microscopy.The electrochemical properties of the composites were studied by cyclic voltammetry and galvanostatic charge-discharge measurements.Results show that when the mass ratio of mesoporous carbon to nickel molybdate is 1:5 during the preparation process,the resulted composite shows an optimal rate performance and stability.When the CNT mass is 0.5%of the Ni-MOF mass,the internal resistance of the composite is the lowest,the discharge time is relatively longer,and the electrical storage performance is the best among the investigated ratios.Moreover,the MOF-derived Nix Co_1-x（OH）₂ material obtained under a 10 h of hydrothermal reaction period exhibits the best electrochemical performance.When the applied current density is 0.3 A g^-1,the power density of the MOF-derived material is97.8 W kg^-1,and corresponding energy density is 43.6 Wh kg^-1,indicating that Ni_xCo_1-x（OH）₂material possesses good application prospect in the field of energy storage.