Doctor of Philosophy
Mechanical and Materials Engineering
All-solid-state lithium metal batteries offer a potential solution to conventional lithium-ion battery limitations, encompassing safety concerns, restricted voltage windows, cycling performance instability, and suboptimal energy density. Utilizing lithium metal anodes and high-capacity cathode materials, these batteries can attain energy densities surpassing 500 Wh/kg, rendering them a promising candidate for electric vehicles necessitating extended driving ranges. Notwithstanding recent advancements, the realization of long-term cycling stability in all-solid-state lithium metal batteries continues to pose challenges, primarily due to the persistent difficulty in mitigating lithium dendrite growth at elevated areal capacities (>3 mAh/cm2) and high cycling rates (>4 C). This thesis seeks to tackle persisting obstacles and foster progress in all-solid-state lithium metal batteries through: a) the innovation of lithium-stable nitride solid-state electrolytes tailored for all-solid-state lithium metal batteries; b) the realization of practical all-solid-state lithium metal battery applications; and c) the utilization of synchrotron X-ray analytical techniques for in-depth characterization of solid-state electrolyte-lithium metal interfaces, thereby augmenting fundamental comprehension. This research develops a series of nitride-based SSEs and processing methodologies aimed at mitigating lithium dendrite growth, while maintaining high stability at increased current densities and areal capacities. Ultimately, by leveraging tailored interface engineering strategies, this work demonstrates practical all-solid-state lithium metal batteries exhibiting high areal capacity (>4 mAh/cm2), rapid charging capabilities (4 C), extended cycling life (5000 cycles), and feasible pouch cell implementations. Utilizing advanced X-ray and electron imaging analytical techniques, this thesis elucidates the interphases' compositions, crystal and local structures, and corresponding distribution parallel and perpendicular to interfaces, as well as the stability of SSE-lithium metal interfaces during electrochemical cycling. In summary, this thesis serves as a critical contribution to advancing all-solid-state lithium metal batteries towards achieving high energy density, thereby addressing the rapidly evolving demands of the electric vehicle market.
Summary for Lay Audience
All-solid-state lithium metal batteries have the potential to overcome the limitations of traditional lithium-ion batteries, which include safety concerns, narrow voltage ranges, unstable performance over time, and lower energy storage. By using lithium metal anodes and cathode materials that can store more energy, these new batteries can hold over 500 Wh/kg of energy, making them a great option for electric vehicles that need to go far on a single charge. However, there are still some challenges to overcome, like the growth of harmful lithium dendrites when the battery is working hard or holding a lot of energy. This thesis aims to tackle these challenges by using advanced X-ray techniques to study how the battery materials interact with each other, creating new materials that work well with lithium metal batteries, and finding practical ways to make these batteries work better in real-life situations. The research has led to a better understanding of the battery materials, developed new methods to reduce the growth of harmful dendrites, and created batteries with high energy capacity, fast charging, long-lasting performance, and suitability for everyday use. In conclusion, this thesis plays a crucial role in pushing all-solid-state lithium metal batteries forward, helping them to achieve higher energy storage and meet the growing needs of the electric vehicle market.
Li, Weihan, "Synthesis and Characterization of Nitride Solid-State Electrolytes for All-Solid-State Lithium Metal Batteries" (2023). Electronic Thesis and Dissertation Repository. 9427.
Available for download on Sunday, August 10, 2025