Publication Date
5-2024
Date of Final Oral Examination (Defense)
December 2023
Type of Culminating Activity
Dissertation
Degree Title
Doctor of Philosophy in Materials Science and Engineering
Department Filter
Materials Science and Engineering
Department
Materials Science and Engineering
Supervisory Committee Chair
Hui (Claire) Xiong, Ph.D.
Supervisory Committee Member
Elton Graugnard, Ph.D.
Supervisory Committee Member
Eungje Lee, Ph.D.
Supervisory Committee Member
Yuzi Liu, Ph.D.
Supervisory Committee Member
Chengjun Sun, Ph.D.
Abstract
As global demand for energy storage rises in response to the proliferation of electric vehicles and intermittent renewable energy sources, the resources associated with popular energy storage systems are increasingly strained. Lithium ion batteries (LIBs) rely heavily on elements with low abundance and unstable supply chains, while sodium ion batteries (SIBs) are a promising alternative technology based on abundant, globally available elements such as iron and sodium. However, the electrochemical performance of SIBs must be improved to enable their commercial viability. In the class of layered transition metal oxide (LTMOs) materials that are strong candidates as positive electrode materials for SIBs, the process of desodiation during charge leads to a variety of degradation mechanisms. Irreversible phase transformations and the reactivity of the surface against electrolyte are particularly pernicious, which makes tools to mitigate these processes highly valuable.
The application of structural heterogeneity is evaluated in LTMOs as a means to mitigate the degradation of these materials at high voltage. First, the role of the transition metal composition in the degradation of the O3-type Na(NiMn)1-xFexO2 system is investigated, identifying the interaction between Ni and Fe at high state of charge and Fe content that harms the reversibility of Ni redox. Next, it is shown that using Li as a dopant in NaxLiyNi0.4Fe0.2Mn0.4O2 can suppress the irreversible phase transformation observed in the undoped material by the mechanical reinforcement from the biphasic Na-O3/Li-O’3 structure. However, the Li doping increases the side reaction at the surface, which can be partially mitigated by Al2O3 coating. An O3/P3 heterostructure can be promoted in NaNi0.5Mn0.5O2 by controlled thermal processing, which can bolster the reversibility of its high voltage redox process. Finally, by manipulating the Na/Li ratio in Na0.67-xLiyNi0.33Mn0.67O2, the location of Li within the structure can be controlled with significant influence on the cycling stability. Further, Li can promote a heterogeneous interlayer ordering of transition metal ions that accelerates Na+ diffusion and yields superior high-rate capacity. Overall, it is found that the thermodynamic and kinetic control of heterogeneous LTMO structures is an effective means to influence their structural stability and other properties.
DOI
https://doi.org/10.18122/td.2166.boisestate
Recommended Citation
Gabriel, Eric, "Stabilization of Layered Transition Metal Oxide Positive Electrodes at High Potential for Sodium Ion Batteries" (2024). Boise State University Theses and Dissertations. 2166.
https://doi.org/10.18122/td.2166.boisestate