Microwave-assisted Preparation In Liquid Phase And Electrochemical Properties Of Copper Oxide Nanomaterials

Supercapacitors play a vital role in energy storage and conversion.However,low energy density greatly limits their application in industrial areas and daily life.CuO,a transition metal oxide,is a good electrode material for supercapacitors owing to a high theoretical specific capacitance and good chemical stability,and it is cheap and environmentally friendly.But the actual capacitance of CuO is much lower than theoretical capacitance due to poor conductivity and structural problem,which seriously hinder its practical application.In order to improve the electrochemical performance of CuO,CuO with two kinds of morphologies of were prepared by simple and time-saving microwave-assisted method in liquid phase,and the composite CuO/MnO₂ was synthesized to further improve the electrochemical performance of CuO.The main work is as follows:Microspherical CuO?W-CuO?and nanosheet-like CuO?P-CuO?were prepared by microwave-assisted method in liquid phase,and the composition,morphology and structure of W-CuO and P-CuO were characterized by X-ray diffractometer?XRD?,X-ray photoelectron spectroscopy?XPS?and scanning electron microscopy?SEM?,respectively.In addition,W-CuO and P-CuO were madeintoW-CuO/nickelfoam?W-CuO/NF?andP-CuO/nickel foam?P-CuO/NF?as working electrodes,and cyclic voltammetry?CV?,galvanostatic charge and discharge?GCD?and electrochemical impedance spectroscopy?EIS?were used to explore the electrochemical properties of W-CuO/NF and P-CuO/NF.The results show that W-CuO/NF?W-CuO/nickel foam?and P-CuO/NF have higher specific capacitance.At the current density of0.5A/g,the former and the latter have capacitance values of 205.4 and 333.2F/g,respectively.The rate capability of both is also good,but P-CuO/NF is more prominent than W-CuO/NF in terms of capacitance and rate capability.In order to further improve the electrochemical performance of CuO,W-CuO/MnO₂ and P-CuO/MnO₂ binary composites were synthesized by microwave-assisted method in liquid phase on the basis of W-CuO and P-CuO,respectively,and the composition,morphology and structure of W-CuO/MnO₂and P-CuO/MnO₂ were tested through XRD,XPS and SEM.Besides,the electrochemical properties of W-CuO/MnO₂/NF and P-CuO/MnO₂/NF were also characterized.The results show that the specific capacitance of W-CuO/MnO₂/NF and P-CuO/MnO₂/NF is obviously improved compared to CuO/NF.At the current density of 0.5A/g,the capacitance values of the former and the latter are up to 326.3 and 470.1F/g,respectively.The rate capability of the two is also good,but P-CuO/MnO₂/NF is better than W-CuO/MnO₂/NF whether capacitance value or rate capability.The button asymmetric supercapacitor,P-CuO/MnO₂/NF//AC,was assembled with better P-CuO/MnO₂ to examine the practicability of CuO/MnO₂binary composite.The supercapacitor displays a specific capacitance of 40.9F/g at 0.1A/g,and a good energy density of 6.9Wh/kg.Moreover,a LED lamp can be smoothly illuminated by P-CuO/MnO₂/NF//AC.