Energy storage is an essential enabler for future sustainable technologies by linking renewable resources with the power grid. Following the great success of rechargeable lithium-ion batteries in the commercial consumer electronics market, the increasing demand for improved energy density, lifetime, and safety in large-scale and power-intensive device applications calls for new materials with novel structures. The fundamental understanding of the structure-property relationship of these materials is critically needed, but barely available on the atomic to nanoscale. Transmission electron microscopy (TEM) is an indispensable technique to offer the spatiotemporal characterization of materials transformation, especially when coupled with advanced in situ and analytical methods, which can address the challenge in correlating the atomic-level structures to the device-level properties. In this seminar, I will focus on our recent development of in situ TEM and its application in energy storage materials. We have demonstrated how to implement multiple imaging modalities of TEM to visualize the dynamic structural evolution during electrochemical reactions in electrode materials with variable crystal structures. Using these methodologies, we further investigated the kinetics and stress effects in two-dimensional materials and then leveraged the obtained findings as guiding principles to develop new materials and architectures for future lithium-ion and beyond-lithium batteries.
Dr. Kai He is an Assistant Professor of the Department of Materials Science and Engineering at Clemson University. He received his Ph.D. from Arizona State University. Prior to joining Clemson in 2018, he was a Research Assistant Professor of the Materials Science and Engineering Department at Northwestern University after postdoctoral training at the University of Maryland and Brookhaven National Laboratory. His research is focused on advanced electron microscopy methodologies and their applications in multifunctional nanomaterials for sustainable energy and quantum information technologies, funded by National Science Foundation, Department of Energy, U.S. Army, and American Chemical Society. He has published more than 80 peer-reviewed papers in high-impact journals. He was the recipient of DOE Early Career Award, NSF EPSCoR Fellowship, American Chemical Society PRF New Doctoral Investigator Award, Microscopy Society of America Presidential Scholar Award, Clemson University Research, Scholarship and Artistic Achievement Award, Clemson University Junior Researcher of the Year, among other recognitions from the academic community.