Abstract:
Core-hole based X-ray spectroscopies used under ex situ, in situ and operando conditions provide information vital to unraveling the mechanisms of charge transfer and structural re-organization of electrochemical materials. In this presentation, we will specifically look at how the core-hole techniques of X-ray absorption can be used in the study of electrochemically active materials such as in batteries and fuel cells, particularly by tuning to resonances in both the soft and hard x-ray regimes. First we will examine the role of oxygen in the charge compensation of LiMO2 compounds and the consequences of such for battery safety and for unprecedented changes to electrical/magnetic properties. The electronic and atomic structure local to oxygen was first examined indirectly using hard x-rays by operando resonant K-level measurements of M atoms in battery cathodes of working batteries. The results were then complemented by direct operando measurements at the K-edge of oxygen atoms in the cathode using soft x-rays. It will be demonstrated that the detailed electrochemical roadmap for the reaction mechanisms in LiMO2 cathodes could only be revealed by a combination of soft and hard x-ray based experiments. Next, we will look at the effects of dimension, strain and charge transfer on the electrochemical activity and durability of electrocatalysts for both low and high temperature fuel cells. Again, it will be demonstrated that a thorough employment of XAFS and its complementary core-hole methods at both soft and hard x-ray regimes is necessary to reveal a detailed story of the reaction mechanisms in working electrocatalysts.
Biography: Dr. Faisal M. Alamgir:
After a BA in physics and mathematics Dr. Faisal M. Alamgir received his Ph.D. in materials science and engineering at Lehigh University for his work on the use of electron microscopy and various spectroscopies to study the high glass-forming ability bulk metallic glasses from the bottom up. The work also involved the development of electron microscopy based techniques for probing sub-nanoscale structure. Following his doctorate, he held a postdoctoral position jointly between Brookhaven National Laboratory (BNL) and Hunter College of the City University of New York for two years where he did research on the development of synchrotron-based in-situ spectroscopies for the dynamic nanoscale study of secondary battery and fuel cell materials. He simultaneously held a position as adjunct professor at Hunter and taught undergraduate physics courses in that capacity. Prior to joining the Georgia Institute of Technology, he spent one and a half year as a Visiting Scientist for the National Institute of Standards and Technology (NIST) where he was one of three scientists in charge of a suite of synchrotron beamlines at BNL.
Dr. Alamgir have been working on in situ/operando methods for unraveling the fundamental mechanisms behind the functioning of Li batteries, fuel cells and other (photo-)electrochemical devices. His research activities and interests include:
• In situ/operando methods for unraveling the fundamental mechanisms behind the functioning of Li batteries, fuel cells and other (photo-) electrochemical devices.
• Development of coking and sulfur tolerant electrodes for SOFCs.