Date of Final Oral Examination (Defense)
Type of Culminating Activity
Doctor of Philosophy in Materials Science and Engineering
Materials Science and Engineering
Michael F. Hurley, Ph.D.
Eric J. Dufek, Ph.D.
Hui (Claire) Xiong, Ph.D.
Paul H. Davis, Ph.D.
Nuclear energy and electrochemical energy storage, such as batteries, are key parts to the clean energy transition of critical infrastructure. This work aims to define, monitor, and modify interfacial layers that would improve the utility of materials in harsh environments seen in nuclear and energy storage applications. First, the studying of zirconium alloys, which is used as nuclear cladding, was done to better understand the degradation mechanisms within an extreme environment. High-resolution characterization techniques were used to correlate corrosion mechanisms to equivalent circuit models from novel in-pile electrochemical impedance spectroscopy sensors. Advancement in this sensor technology could provide further insight and monitoring of the complex degradation mechanisms in a harsh nuclear core environment. A novel method was developed to spatially map Raman spectral features throughout the oxide cross-section, revealing a direct correlation between tetragonal zirconia phase and compressive stress, thus supporting the theory of a stress-induced breakaway phenomenon. Additionally, a comparison of interface- and relaxed-tetragonal phase revealed a difference in stabilization mechanisms, where relaxed-tetragonal phase is stabilized solely from sub-stoichiometric contributions. Coupling Raman mapping with elemental analysis via energy dispersive X-ray spectroscopy and scanning Kelvin probe force microscopy led to a distinction of secondary-phase particles and their nobility relative to surrounding zirconium oxide and metal. Lastly, a p-n junction at the tetragonal/monoclinic zirconia interface was observed, supporting the theory that the tetragonal layer at the metal/oxide interface provides an additional barrier to an otherwise diffusion-limited oxidation mechanism.
Other interfacial studies were conducted on next-generation battery anodes. High-capacity lithium, deemed the “Holy Grail” of battery materials, undergoes unstable interactions in most, if not all, environments. In a cell, this causes poor cycle life and/or possible safety concerns via dendritic-driven short circuiting. Novel development of lithium-metal batteries was accomplished firstly with a facile design of a closed-host, porous/dense bi-layer interfacial structure formed on lithium through a two-step ex situ/in situ process, only made possible with an electrolyte additive included in the cell. This design prevented dendrite growth, improved interfacial flexibility and ionic conduction when compared to a traditional LiF coating, reduced volume fluctuations, and prevented extensive parasitic reactions. In summary, the works presented here were done in effort to better understand and control interfacial mechanisms in both nuclear energy and energy storage fields.
Efaw, Corey Michael, "How to Recognize and Control Interfacial Phenomena That Hinder the Advancement of Clean Energy Technologies" (2021). Boise State University Theses and Dissertations. 1912.