Date: Tuesday, June 1, 2021
Time: 11:00 am
Talk Title: Nanoscale Solid-Liquid Interfaces: In-Situ and Cryo Electron Microscopy
Understanding the interfacial processes that occur at a metals’ surface requires in-situ observation and high-resolution static characterization. We have used these tools to explore electrodeposition mechanisms of Li-anode batteries for high-capacity energy storage, and separately for corrosion mechanisms in low-carbon steel. This presentation will cover the methods and insights that we have gained from investigating these two systems and the workflows that will enable a deeper understanding of similar systems. Tools include a cryogenic transfer suite to move air sensitive materials from a glovebox to a cryo-focused ion beam (FIB)/scanning electron microscope (SEM), then into a cryo- transmission electron microscopy (TEM) holder for Scanning/TEM and electron energy loss spectroscopy analysis. A femtosecond laser on the side of a plasma FIB was used to section through intact Li-metal battery coin cells to observe the Li morphology and solid electrolyte interphases’ (SEI) interaction with the polymeric separator, which identified the SEI’s role in carving electronic bridges through the separator. Liquid-cell TEM holders have been used to study the initiation mechanisms of pitting corrosion in low carbon steel, where thickness and grain orientation mapping has identified the microstructural sites most susceptible for initiation of localized corrosion. Finally, a microelectromechanical (MEMS) platform is being developed to extend the experimental capabilities of in-situ liquid-cell TEM experiments for quantitative tension testing in atmospheric gaseous or liquid environments with elevated temperature control.
Katherine Jungjohann received her doctoral degree in Materials Science and Engineering from the University of California, Davis in 2012. Her topic of study was on the imaging and growth of nanostructures in liquid using high-resolution in-situ scanning/transmission electron microscopy. She completed a Postdoctoral Fellowship at the Center for Functional Nanomaterials at Brookhaven National Laboratory, continuing on imaging the formation of bimetallic nanoparticle catalysts. Since 2013, she has been a staff member at the Center for Integrated Nanotechnologies at Sandia National Laboratories with current research interests in energy storage materials, corrosion, nanoparticle assembly, and the coupled mechanical-environmental properties of nanoscale materials. In 2016-2017 she served on the Early Career Advisory Board for Nano Letters. Currently, she serves as the co-leader of the Microscopy Society of America’s Focused Interest Group on Electron Microscopy in Liquids and Gases, which she also holds the Placement Office Chair for this society.