Abstract
The rapid expansion of electrified transportation and renewable energy integration demands advanced lithium-ion (Li-ion) and sodium-ion (Na-ion) batteries with enhanced safety, long-term reliability, and high energy efficiency. However, conventional systems employing liquid electrolytes continue to exhibit persistent failure modes, including thermal instability, parasitic interfacial reactions, transition-metal dissolution, and electrode degradation under high-voltage or fast-charging conditions. These limitations become even more critical in solid-state configurations, where insufficient ion mobility and interfacial incompatibility can severely restrict electrochemical performance. The first part of this dissertation develops an atomic-layer-scale interfacial stabilization strategy using atomic layer deposition (ALD) coatings. ZnO-modified graphite anodes in Li-ion cells exhibited more uniform and chemically stable solid layer interface (SEI) layers, lower interfacial impedance, and improved cycling life compared to uncoated electrodes. Applying ALD coatings (ZnO, Al2O3, NiO, TiO2) to P2-type Na0.7MnO2 (NMO) cathodes for sodium ion battery effectively suppressed Jahn-Teller distortion, inhibited Mn dissolution, and reduced electrolyte decomposition, leading to stabilized cathode structures and stronger cathode layer interface (CEI) integrity under high-voltage cycling. This work demonstrates that ultrathin ALD coatings can precisely tune electrochemical reactions at buried interfaces without altering bulk material composition. The second part of this dissertation focuses on solid polymer systems (SPEs) and addresses the intrinsic limitations of polyethylene oxide (PEO), including high crystallinity and insufficient modulus at moderate temperatures. New polymer structural designs based on amorphous co polymers such as poly(propylene glycol) (PPG) and poly(ethylene glycol-ran-propylene glycol) (PEG-PPG) incorporation significantly increased the amorphous phase fraction, boosted Li+ transport, expanded electrochemical stability, and improved interfacial contact with electrodes during high-temperature operation. For Na-ion systems, ceramic-reinforced composite polymer electrolytes (CPEs), containing ceramic nanofillers, formed faster Na+ diffusion channels, reduced grain-boundary resistance, and improved electrochemical stability when paired with ALD coated cathodes. These results confirm that polymer architecture and inorganic nanostructure must be co engineered to achieve competitive solid-state performance. The third part of this dissertation investigates microstructural engineering in NASICON type Na3Zr2Si2PO12 (NZSP) ceramic electrolytes, which possess inherently high Na⁺ conductivity yet suffer from grain-boundary limitations. Comparative fabrication studies revealed that ALD assisted conventional sintering provides superior densification, greater grain-boundary continuity, and significantly reduced interfacial resistance relative to pristine or physically mixed NZSP. When integrated with coated NMO cathodes, the ALD engineered NZSP enabled improved electrochemical performance and more stable solid-solid contact. This work establishes microstructure-controlled ceramic processing as a critical requirement for scalable, high performance oxide solid-state electrolytes. Collectively, this dissertation shows that interfacial chemistry and microstructural uniformity, rather than bulk composition alone, govern the transport behavior, stability, and lifetime of both liquid-electrolyte and solid-state batteries. By integrating ALD surface engineering, polymer crystallinity control, and ceramic grain-boundary optimization, this research provides a unified pathway toward safer, longer-lasting, and higher-efficiency energy storage systems for next-generation battery technologies.
Committee Chair
Xinhua Liang
Committee Members
Chris Cooper; Peng Bai; Vijay Ramani; Xianglin Li
Degree
Doctor of Philosophy (PhD)
Author's Department
Energy, Environmental & Chemical Engineering
Document Type
Dissertation
Date of Award
2-24-2026
Language
English (en)
Recommended Citation
Helaley, Ahmad, "Interfacial Engineering of Electrodes and Solid-State Electrolytes for High-Performance Lithium-Ion and Sodium-Ion Batteries" (2026). McKelvey School of Engineering Theses & Dissertations. 1333.
The definitive version is available at https://doi.org/10.7936/k7r1-9r90