Title:

Interplay of Chemistry and Function in the Interphases of Lithium and Calcium Metal Anodes for High-Energy Rechargeable Batteries

Speaker:

Prof. Betar M. Gallant

Affiliation:

Department of Mechanical Engineering, Massachusetts Institute of Technology

When:

Friday, April 15, 2022 at 11:00:00 AM   Add to Calendar

Where:

GTMI Building, Room MARC Auditorium

Host:

Dr. Seung Woo Lee
seung.lee@me.gatech.edu
404-385-0764

Abstract

Metal anodes offer significantly higher capacities than graphite and are therefore central to strategies to develop advanced rechargeable battery chemistries that meet range and performance targets for electric vehicles. Although closer than ever, lithium (Li) anodes still cannot meet the 99.9 Coulombic efficiency (CE) consistently needed for 1,000 cycle life. This shortfall arises from uncontrolled reactivity at the solid electrolyte interphase (SEI) and its resulting properties, leading to inhomogeneous plating and stripping, continuous electrolyte consumption and loss of active Li inventory. Despite much recent progress in electrolyte development, the lack of precise understanding of functionality from the perspective of the SEI itself still hinders attempts to rationally design an improved interface and bridge the remaining gap in CE. To help inform such efforts, our work is developing techniques to gain insights into SEI phases and reveal interplays between their chemistry, structure and function. We are developing approaches to isolate and synthesize phases relevant to the native Li SEI at nanoscale thickness directly on Li metal. These interfaces are then interrogated via targeted electrochemical and spectroscopy techniques to reveal their transport properties, Li exchange kinetics and chemical reactivity in different electrolytes, providing insight into how such phases may function in a native SEI. I will also discuss additional efforts to advance quantification techniques for studying the proportions and evolution of phases during initial SEI formation and over cycling. By applying these tools to high and low CE electrolytes alike, we ultimately aim to identify descriptors that can support continued development of advanced electrolytes and additives. Recently, we are also translating these efforts to study Ca metal anodes, which remain in much earlier stages of research due to particularly severe challenges originating with the Ca SEI. I will describe some key similarities and differences between Li and Ca that are informing our approach to Ca interface characterization, Ca foil testing and speciation studies in leading electrolytes developed recently. Early findings are revealing how Ca2 coordination can dramatically influence the activity – or lack thereof – of Ca plating/stripping, which directly relates to the nature of the formed interface.

Biography

Betar M. Gallant is an Associate Professor and the ABS Career Development Professor in the Department of Mechanical Engineering at MIT. She obtained her SB, SM, and PhD degrees from the same department, where she was an NSF Graduate Research Fellow, MIT Energy Initiative Fellow and MIT Martin Family Fellow during her graduate work. Following her PhD, Dr. Gallant was a Kavli Nanoscience Institute Postdoctoral Fellow at Caltech. Her research group at MIT focuses on advanced battery chemistries and materials for high-energy primary and rechargeable batteries, including fluorinated cathode conversion reactions and lithium and calcium metal anodes and their interfaces. Her group is also leading research into CO2 capture and its integration with direct electrochemical conversion in the captured state. She is the recipient of multiple awards including an MIT Bose Fellow, Army Research Office Young Investigator Award, Scialog Fellow in Energy Storage and in Negative Emissions Science, NSF CAREER Award, ECS Battery Division Early Career Award, and the Ruth and Joel Spira Award for Distinguished Teaching at MIT.

Notes

Lunch will be provided.