Preparation And Storage Behavior Of Manganese-Cobalt-Based Metallic Oxides And Their Nanocomposites

Supercapacitor has higher power density than battery,and higher energy storage density than traditional capacitor.It can filter or store electric energy generated by solar energy,wind energy and other means into convenient energy,and can also be used in military fields such as electromagnetic ejection,electromagnetic gun and so on.Therefore,it is desirable to study the electrode materials of supercapacitors with more application value.In this paper,the electrochemical properties of MnCo₂O₄ were improved by changing the morphology structure and composite materials.The structure and micro morphology of MnCo₂O₄ were analyzed by XRD,SEM and TEM.The capacitance properties of MnCo₂O₄ were analyzed by Cyclic Voltammetry,Galvanostatic Charge–Discharge and other tests under the three-electrode system.The main research contents are as follows:1.The filiform MnCo₂O₄ was prepared by electrospinning,the granular MnCo₂O₄and urchin-like MnCo₂O₄ were prepared by hydrothermal method,and the structure and morphology information were determined by XRD and SEM.Through the test of electrochemical workstation,it is found that when the current density is 1Ag^-1,the specific capacitance of filiform MnCo₂O₄ is 161Fg^-1,that of urchin-like MnCo₂O₄ is206Fg^-1,and that of granular MnCo₂O₄ is 131Fg^-1.Urchin-like MnCo₂O₄ has better capacitance performance because its complex nano structure provides more active sites.After 1000 cycles of filiform MnCo₂O₄,the capacity retention rate is 93%,while that of urchin-like MnCo₂O₄ is 87%.The capacity retention rate of filamentous MnCo₂O₄benefits from the structural advantages of filaments.Filaments MnCo₂O₄ could collude with each other,which is conducive to electronic transport and mutual support to improve the cycle performance.2.The urchin-like MnCo₂O₄ was compounded with g-C₃N₄ in different proportion by hydrothermal method,and samples C1,C2,C3 were obtained.XRD and SEM analysis show that the composite is in good condition.When the current density is 1Ag^-1,the specific capacitance of sample C1 is 229Fg^-1,sample C2 is 350Fg^-1,sample C3is 342Fg^-1.Experiments show that g-C₃N₄ can effectively disperse and improve the conductivity of urchin-like MnCo₂O₄,and the composite of sufficient g-C₃N₄ can give full play to the performance of urchin-like MnCo₂O₄,provide faster electronic transport channels,effectively improve the ion migration rate,and make urchin-like MnCo₂O₄increase the rate performance under high charge and discharge rate.3.MnCo₂O₄/Co₂V₂O₇ composite was obtained by hydrothermal method.Its crystal structure,microstructure and composite were confirmed by XRD,SEM and TEM.The specific capacitance of MnCo₂O₄/Co₂V₂O₇ is 375Fg^-1 at the current density of 1Ag^-1,while that of granular MnCo₂O₄ and Co₂V₂O₇ are 131Fg^-1 and 157Fg^-1 at the current density of 1Ag^-1.MnCo₂O₄/Co₂V₂O₇ composite with the batter performance is due to the mutual cooperation of the storage mechanism that the Co₂V₂O₇ with intercalation reaction energy storage behavior and the MnCo₂O₄ with battery-like energy storage behavior.Herein,based on the preparation of electrode materials with different micro morphology,and focusing on some challenges to improve the electrochemical performance of transition metal oxide electrode materials,it is proposed to form composite materials by combining MnCo₂O₄ with g-C₃N₄ and Co₂V₂O₇,and to explore the influencing factors in practical application,which provides a feasible strategy for the synthesis of supercapacitors.