Abstract

Lithium-ion batteries have become indispensable to modern society, driven by the increasing demand for higher energy density within limited space. Despite their success, further breakthroughs are required to meet the growing needs of electrification and portable energy storage. One promising pathway is the development of all-solid-state batteries, in which a solid electrolyte is paired with a lithium metal anode possessing a significantly higher theoretical capacity than conventional graphite. However, the use of lithium metal with liquid electrolytes is hindered by non-uniform plating and rapid dendrite penetration during recharge, leading to premature failure and safety concerns. Solid-state electrolytes offer the potential to mechanically suppress such instabilities and eliminate flammable components, yet lithium penetration through these materials has been widely observed. The variability in physical properties and electrochemical behavior associated with these failure modes has hindered the development of a unified mechanistic understanding. In the first part of this work, a scalable approach for achieving high and uniform densification of garnet-type solid electrolytes is demonstrated using conventional furnace sintering. By controlling the local lithium chemical environment through optimized crucible configurations, sacrificial pellet architectures, and lithium-rich precursor powder beds, lithium volatilization is suppressed and impurity formation is minimized. This enables the fabrication of LLZO pellets with high relative density (~96%) and improved reproducibility without the need for pressure-assisted techniques such as spark plasma sintering or rapid induction hot pressing. In the second part, the mechanisms governing dendrite initiation in ceramic solid electrolytes are investigated. Through systematic electrochemical measurements, including linear sweep voltammetry and impedance spectroscopy, transient concentration polarization is identified as a precursor to dendrite formation. These results reveal that dendrite initiation in ceramic electrolytes is governed by transport limitations analogous to those observed in liquid electrolytes. To isolate intrinsic material behavior, a one-way lithium deposition method is employed, eliminating interfacial artifacts commonly introduced during galvanostatic cycling. This approach enables the identification of a new metric, the breakthrough current density, which exhibits strong dependence on electrolyte thickness and provides a more consistent measure of electrochemical stability. Together, these findings establish a unified framework linking dendrite initiation to transport-driven instabilities in both solid and liquid electrolyte systems. In the final part, results addressing industry-relevant challenges are discussed. Overall, this dissertation demonstrates that both materials processing and failure mechanisms are fundamentally governed by electrochemically driven transport phenomena in ceramic solid electrolytes. By establishing connections between densification, microstructure, and transport-limited behavior, this work provides new insights and scalable strategies for the development of next-generation solid-state and lithium-ion batteries.

Committee Chair

Peng Bai

Committee Members

Elijah Thimsen; Katharine Flores; Rohan Mishra; Vijay Ramani

Degree

Doctor of Philosophy (PhD)

Author's Department

Energy, Environmental & Chemical Engineering

Author's School

McKelvey School of Engineering

Document Type

Dissertation

Date of Award

5-6-2026

Language

English (en)

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Available for download on Tuesday, June 15, 2027

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