Preparation And Supercapacitor Properties Of Structural Transition Metal Oxide/hydroxide Composites

In this thesis,some structural transition metal oxide and/or hydroxide composite materials were designed and fabricated for using as supercapacitor electrodes.We obtained some kinds of electrode materials with different microtopography.By the design of structure of nanomaterials,not only can we improve the specific surface area of the electrodes to add the mass-loading of active components,but also shorten the diffusion pathway of electrolyte ions to get a high-efficiency transformation between electrolyte-ion and electron.Due to these factors,these electrode materials may be of excellent supercapacitor performances.Our main researches are as follow:(1)Fabricating the hollow tubular Ni-Co hydroxide/Cu(OH)2/CF by chemical oxidation and electrochemical synthesis process.We study the microtopography of this electrode material by SEM,TEM,HRTEM,XPS and the electrochemical performance by electrochemical workstation.The result shows that this electrode material is of excellent supercapacitor property(5 mA cm-2,849.6 C g-1,2095 F g-1).However,we try to undertake a scale-up synthesis experiment by this method.Amazingly,we find the supercapacitor property of the product is comparable to the former.(2)Following by the hydrothermal synthesis and in-suit oxidation process,we fabricate the ultrathin CoOOH nanosheet array on Nickle foam.Also,we study the microtopography of this electrode material by SEM,TEM,HRTEM,XPS,AFM and the electrochemical performance by electrochemical workstation.The result shows that this electrode material is of excellent supercapacitor property(1.25 A g-1,2550 F g-1),due to its ultrathin nanosheet structure(less than 3 nm),which is good for utilizing the active sites effectively.Meanwhile,we evaluate the performance of asymmetric supercapacitor(ASC)by using the CoOOH/NF as positive electrode and RGO as negative.When the power density is 435 W Kg ',its energy density can be up to 49.8 Wh Kg-1.(3)Last few decades,the limitation of application of supercapacitor is mainly due to its low energy density.Improving the energy density as much as possible,will be the most significant effort for supercapacitor researches.Obtaining an ideal negative electrode material,property is comparable to positive electrode,may be the key to solve this problem.On the other hand,inspired by our former work(the fabrication of Ni-Co hydroxide/Cu(OH)2/CF),we decide to try to design and fabricate the hollow tubular Fe304@C/Cu0/CF material as negative electrode.At the same time,we test the electrochemical performance of this energy storage device(Fe3O4@C/CuO/CF as negative electrode and Ni-Co hydroxide/Cu(OH)2/CF as positive electrode),which shows an outstanding electrochemical property:when the power density is 184 W Kg-1,the energy density is about 94.8 Wh Kg-1.