Metal oxide/hydroxide and their composite materials for supercapacitor application
Date of Issue2015
School of Materials Science and Engineering
Supercapacitors are a kind of electrochemical energy storage devices, which can provide high power transient energy supply. They have moderate energy density ~ 10 Wh kg-1 and high power density up to 10 kW kg-1. The enhancement of energy density of supercapacitor will be benefit for various applications, such as consumer device, energy backup, industrial heavy duty machine and so on. This thesis focuses on the strategies to enhance the electrochemical energy storage performance of pesudocapacitive metal oxide/hydroxide materials. The corresponding strategies are: 1) constructing one dimensional electrode nanostructure of active material (NixCo4-xO4 polycrystalline nanowire, Ni-Co layered double hydroxide-Zn2SnO4 hybrid material); 2) hybridization of active material with conducting additives (NixCo4-xO4 reduced graphene oxide composite material); 3) enhancing the electric conductivity of pristine active material (Ni-Co-Al layered hydroxides); 4) creating facile mass transfer by novel device configuration (fabrication of interdigitated finger electrode based micro supercapacitor using MnOx-polyaniline). Based on these strategies, several physical/electrochemical factors are found to be crucial in achieving high electrochemical performance, such as high aspect ratio nanowire structure, the effective electrochemical active area, fast surface faradic reaction, and high aspect ratio design of interdigitated electrodes. The rational design of electrochemically active materials, as well as the micro electrode device, lead to enhanced supercapacitor properties with higher energy densities and higher power densities. Overall, this thesis contributes to the rational design, synthesis, and insightful understanding to the electrochemical behavior of metal oxides/hydroxides and their composite materials.