Investigation of asymmetric hybrid supercapacitor based on morphology of zinc oxide electrode materials for high energy supercapacitors

Official URL: https://risc01.sabanciuniv.edu/record=b2486384 _(Table of contents)

Supercapacitors are highly attractive for large number of emerging mobile devices for energy storage and harvesting issues. In this thesis, we present a summary of the recent developments in supercapacitor research and technology, including all kinds of supercapacitor design techniques using various electrode materials and production methods. It also covers the current progress achieved in novel materials for supercapacitor electrodes. The latest produced EDLC, Hybrid, Pseudo supercapacitors have also been described. Metal oxides, specifically ZnO, used as electrode materials with different morphologies are in focus here. The ZnO nanostructures were synthesized in the form of nanoparticles, nanoflowers and nanourchins. Structural, electronic and optical characterization of the samples were done via standard techniques such as XRD, SEM, Photoluminescence, Raman and UV-Vis spectroscopy. The point defect structures which are specific to each morphology has been investigated in terms of their concentration and location via state of art EPR spectroscopy. According to core-shell model the samples all revealed core defects however the defects on the surface smeared out. Finally, all three morphology has been tested as electrode material in a real supercapacitor device and the performance of the device, particularly the specific capacitance and the storage mechanism has been mediated by the point defects. Morphology dependent defective ZnO electrode enable to monitor the working principle of supercapacitor device from EDLC to pseudosupercapacitor