Center for Functional Nanomaterials Seminar

With rising energy consumption, there is a growing demand for portable and high-performance energy storage devices. Electrification through batteries is essential to reduce usage of fossil fuels and mitigate excessive greenhouse gas emission. While lithium (Li)-ion batteries have experienced substantial technological advancements, they are approaching their theoretical capacity limit. As a result, Li-metal batteries have emerged as promising next-generation solutions, as they can maximize energy density by replacing heavy graphite electrodes with light Li-metal. However, the development of Li-metal batteries faces critical challenges because of unstable dendritic growth which leads to capacity degradation, internal shorts, ultimately thermal runaway. This dendric growth is largely affected by the nature of solid electrolyte interphases (SEI). The SEIs layers control electron and ion pathways, controlling the overall behavior of Li metal batteries. Therefore, fundamental understanding of SEIs is imperative to manufacture stable and high performing batteries. In this talk, I will discuss how SEIs can be imaged and structurally characterized by cryogenic electron and ion microscopy. I will start by introducing the cryogenic lift-out method, which enables the preparation of electron transparency from bulk battery materials. Then, I will highlight the use of cryogenic scanning electron nanobeam diffraction (SEND) to observe order and disorder within SEIs. My finding reveals that the SEIs turned out to be largely amorphous, but they have varying degrees of order and disorder that significantly correlate with the Li metal battery performances. Finally, I will briefly discuss the characterization of amorphous solid electrolytes, bridging between my Ph.D. research on interfacial characterization and my postdoctoral work on solid-state battery materials.