Doctor of Philosophy (PhD)
Materials Science and Engineering
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Materials Science and Engineering
Date of Defense
Hybridization of lithium-ion batteries (LIBs) and electrochemical capacitors (ECs) at electrode level can potentially provide high-performance capacitive energy storage having a good combination of high energy density, high power density, and moderate cycling longevity. Lithium-ion hybrid capacitor (LIHC) system consisting of a battery-type anode and a capacitor-type cathode represents an attractive hybridization approach aimed at bridging the performance gap between the two energy storage systems. The application of such energy storage system may extend the functionalities of many electronic devices.
In this dissertation, different LIHC configurations were designed and evaluated. An LIHC device comprising electrostatically sprayed reduced graphene oxide (rGO)-based material as both electrodes were fabricated and studied in organic liquid electrolyte media. Both electrochemical and direct lithium contact pre-lithiation approaches were explored to achieve high electrochemical performance. Moreover, in contrast to the widely used battery-type anode, an LIHC with battery-type cathode and rGO-based anode was assembled and evaluated. The LIHCs show high electrochemical performance output intermediate between LIBs and ECs.
The second part of the dissertation focused on the fast cycling of lithium titanate anode in ionic liquid-based electrolyte for LIHC. It was shown that porous binder-free LTO electrode prepared by electrostatic spray deposition (ESD) delivered better fast-cycling capability than conventional electrode preparation method comprising polymer binder.
In the last part of the dissertation, on-chip LIHC with three dimensional (3D) interdigital carbon microelectrode platform derived carbon microelectromechanical systems (C-MEMS) technique by was fabricated and examined. The 3D carbon structures played the dual role of the current collector and capacitor electrode, while LiFePO4 was employed as the battery electrode. The on-chip LIHC generated a maximum footprint area normalized energy density of about 5.03 μWcm-2, which was about five times more than symmetric ECs of the same footprint area.
Previously Published In
Some parts of the dissertation have previously been published:
- Adelowo, E., Baboukani, A. R., Chen C., and Wang, C., Electrostatically sprayed reduced graphene oxide-carbon nanotubes electrodes for lithium-ion capacitors, C-Journal of Carbon Research, 2018, 4,31.
- Adelowo, E., Baboukani, A. R., Agrawal, R., and Wang, C., Electrochemical Performance of Lithium-Ion Capacitor Using Reduced Graphene Oxide–Carbon Nanotube Pre-Lithiated by Direct Contact Method ECS Trans. 2018 85,13, 469-474.
Adelowo, Ebenezer Dotun, "Lithium-Ion Hybrid Capacitor Devices: Towards High-Performance Electrochemical Capacitive Energy Storage" (2019). FIU Electronic Theses and Dissertations. 4363.
Available for download on Sunday, August 15, 2021
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