Fabrication Of Three-dimentional Porous Nanostructured Metal-based Complex Film Electrodes And Their Pseudocapacitive Properties

With high power density, excellent cycle capacity and charge-discharge efficiency, supercapacitor has been regarded as a new and potential energy storage device, whose capacitive performance is strongly relied on the properties of electrode materials. Recently, the transition metal oxides such as cobalt and nickel oxide has been paid more attention on and can be used as a new type eletrode material, due to their high theoretical capacitance, low cost, environment friendliness and easy preparation.In this thesis, three-dimentional nanoporous Co/Co O and Co-Ni/Co O-Ni O film electrodes have been designed and synthesized through a combination of template method and electrochemical deposition process with the following heat treatment. The morpology,structure and composition are characterized by coresponding testing and analysis methods. The as-prepared film electrode were evaluated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance measurements. The main results are listed as following:(1) The fabricated three-dimentional Co/Co O film electrode shows the superior properties than the conventional method. At the current density of 4 m A/cm2, the capacity of Co/Co O is 0.26 F/cm2(572.8 F/g). After 60 000 continuous charge-discharge cycles, the areal capacitance retention is nearly 100%, indicating the excellent cycling stability.(2) The Co-Ni/Co O-Ni O composite film was fabricated by using the aqueous solution of Co salt and Ni salt at a certain mole ratio as the electrolyte. When nCo:nNi =(3:7), Co-Ni/Co O-Ni O composite film electrode exhibit an specific capacitance of 2.35 F/cm2(450 F/cm3)at 10 m A/cm2, and the power density and energy density are 12.7 Wh/L和 450 W/L, respectively. The electrochemical cycling stability was measured, after 5 000 continuous galvanostatic charge-discharge cycles and the capacitance retention is highly up to 89.7%. The excellent psedocapacitive performance such as superior capacitive properties, outstanding rate capability and good cycling stability of the as-prepared Co-Ni/Co O-Ni O composite film oxide integrated film electrode suggest its potential application in supercapacitors.(3) The Co-Ni/Co O-Ni O composite film with different pore structure was fabricated, and the results show that Co-Ni/Co O-Ni O composite film electrode with 3D hierarchical nanoporous structure displays more excellent electrochemical performance, compared with the single three-dimentional mesporous structure. After intensive activation through repeated charge/discharge, an ultra-large areal capacitance of 9.8 F/cm2 is achieved, along with a record high volumetric capacitance of 1960 F/cm3 and gravimetric capacitance of 817 F/g。Besides, the composite film shows outstanding rate performance and cycling stability capacity. All the results indicate that this composite film electrode is very promising for energy storage application.