Woodruff School of Mechanical Engineering
Mechanical Engineering Seminar
Exploring ionic dynamics and nanoscale eletrochemistry in solids by advanced SPM
Dr. Evgheni Strelcov
National Institute of Standards and Technology and Visiting Assistant Research Scientist at University of Maryland, College Park
Wednesday, March 9, 2016 at 3:00:00 PM
MRDC Building, Room 4211
Dr. Peter Hesketh
Ion transport enables operation of numerous electrochemical devices including fuel cells, batteries, gas- and biosensors, smart windows, memristive and electroresistive memories. The characteristic size of the active elements of these devices (grain boundaries, conductive filaments, etc.) as well as the interaction length scales (screening, barrier widths) is often in the nanometer range. In contrast to electronic systems, in which miniscule electronic flows can be manipulated in semiconductor devices over trillions of operation cycles, we have little control of ionic flows at the nanoscale. Our lack of understanding and control of ionic flows partly accounts for ion battery degradation after only hundreds of cycles. Thus, understanding the operating mechanisms and subsequent rational device optimization requires ability to probe ionic dynamics in solids locally, i.e. at the nanoscale. In this talk I will introduce two novel scanning probe microscopy (SPM) techniques that address this issue by detecting electronic and ionic responses and local electrochemical activity. The time-resolved Kelvin probe force microscopy method separates surface vs. bulk ionic activity on insulating surfaces in the time domain. The first order reversal curve current-voltage spectroscopy employs the coupling between the ionic motion and electronic conductivity to measure the former. Discussion of the usage and benefits of both techniques as well as the use of multivariate statistical methods for extracting physical meaning from the multidimensional datasets will follow. The presentation will be closed with an outlook section focusing on combining advances SPM with recently-developed lithium-ion microscopy.
Dr. Strelcov is a Postdoctoral Researcher at National Institute of Standards and Technology and Visiting Assistant Research Scientist at University of Maryland, College Park. Prior to joining NIST/UMD he was a Postdoctoral Associate at Oak Ridge National laboratory. He received his PhD in Applied Physics in 2011 from Southern Illinois University and MS degree in Inorganic Chemistry in 2004 from Moldova State University, Moldova. He has published 53 papers on topics including advanced scanning probe microscopy, bias-induced transformations in low dimensional materials, surface electrochemistry and gas sensorics.
Refreshments will be served.