CAREER: Nano Electro-chemo-mechanics and Interfacial Stability in All-solid-state Lithium Battery

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This Faculty Early Career Development (CAREER) grant will focus on understanding the fundamental reaction mechanisms in all-solid-state lithium batteries to identify the root causes of the failures. All-solid-state battery is one of the promising candidates as the next generation energy storage technology beyond Li-ion batteries. It uses solid electrolytes eliminating the use of the flammable liquid electrolyte and is expected to improve safety as well as the energy density. However, the solid nature of the electrolyte causes several issues such as slow ionic conductance and mechanical fractures leading to the premature failure of the device, in particular at the electrochemical interfaces where complex interactions between chemical reactions and mechanical deformations take place. The fundamental insights obtained in this study can be strategically utilized to design the solid electrolyte composition and the interfacial structure to significantly improve the ionic conduction and the mechanical stability for enhancing the performance and the cycle lifetime. It will contribute to develop advanced energy storage devices beyond current Li-ion battery technologies leading to a more sustainable society and economy in the country and the world overall. The research will also incorporate educational and outreach programs to train undergraduate/graduate students and attract K-12 students to STEM fields. In addition, the project organizes an exchange program with an international automobile company contributing to the development of the industry and produce next generation scientists/engineers who have both industrial and academic experience. This project aims to discover the underlying science and the unit processes of the failures in all-solid-state lithium batteries at the electrochemical interfaces. To achieve the goal, an in-situ transmission electron microscopy technique developed by the PI will be employed. It enables precise evaluation of the interplay between the strain/stress evolutions and the changes in the microstructure/chemistry at the interface during electrochemical reactions in atomic- and nano-scales. This method is systematically incorporated in the research to address the important questions for understanding failures in all-solid-state lithium batteries: 1) How does the microstructure of the electrolyte/electrode change during charging/discharging? 2) How does the lithium metal penetrate through the solid electrolyte? and 3) What causes the solid electrolyte to fracture? Atomistic simulations will be performed to construct a theoretical framework on the reaction kinetics and the mechanical properties at the interfaces. This, in combination with the experimental observations and measurements, further promotes the understanding of the reaction/degradation mechanisms.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.