Electrochem Seminar- "Nano-FTIR Spectroscopy of the Solid Electrolyte Interphase Layer on a Thin-Film Silicon Li-ion Anode"

Electrochem Seminar- "Nano-FTIR Spectroscopy of the Solid Electrolyte Interphase Layer on a Thin-Film Silicon Li-ion Anode"

Abstract

Si anodes for Li-ion batteries are notorious for their large volume expansion during lithiation and the corresponding detrimental effects on cycle life. However, calendar life is the main roadblock for widespread adoption. During calendar life aging, the main origin of impedance increase and capacity fade is attributed to the instability of the solid electrolyte interphase (SEI). In this work, we use ex situ nano-FTIR spectroscopy and X-ray photoelectron spectroscopy (XPS) to characterize the structure and composition of the SEI layer on amorphous Si thin films after an accelerated calendar aging protocol. The characterization of the SEI on non-washed and washed electrodes shows that brief washing in DMC results in large changes of the film chemistry and topography. Detailed examination of the non-washed electrodes during the first lithiation and after an accelerated calendar aging protocol reveal that PF6- and its decomposition products tend to accumulate in the SEI due to the preferential transport of PF6- ions through PEO-like species in the organic part of the SEI layer. This work demonstrates the importance of evaluating the SEI layer in its intrinsic, undisturbed form. New strategies to improve the passivation of the SEI layer are proposed.

Speaker

Andrew Dopilka

Andrew is a postdoctoral researcher in Robert Kostecki's group. He is investigating the inherent instability of the solid electrolyte interphase (SEI) on Si anodes in Li-ion batteries. By implementing in situ sSNOM-based infrared nanospectroscopy, the nanoscale inhomogenities of the SEI can be correlated to its electrochemical stability under realistic operating conditions. Andrew recieved a Ph.D in Materials Science and Engineering in 2021 under the supervision of Professor Candace K. Chan and a B.S.E in Chemical Engineering from Arizona State University. His doctoral worked involved investigating Tetrel clathrates,a type of host guest structure, as novel anodes for Li-ion battery materials. The structural transformations of the clathrates during lithiation were investigated with a combination of electrochemical, structural, and first principles computational methods. Andrew is broadly interested in understanding the fundamental phonemona of energy storage materials in addition to developing novel synthetic methods to realize unique properties. Google Scholar

Date/Time
Monday, November 21, 2022 - 03:00pm to 03:30pm
Type
Seminar
PI
Robert Kostecki