Understanding Materials and Interfaces in Solid-State Batteries

Solid-state batteries offer the promise of improved energy density and safety compared to lithium-ion batteries, but degradation of materials and interfaces can play an outsized role in limiting their performance. Here, I will present our emerging understanding of the key differences between how high-capacity anode materials behave in solid-state batteries compared to in conventional liquid-electrolyte batteries. The electro-chemo-mechanical evolution of materials at solid-solid electrochemical interfaces is different than at solid/liquid interfaces, and contact evolution in particular plays a critical role in determining the behavior of solid-state batteries. Lithium metal anodes offer high lithium storage capacity, but they tend to lose contact at solid-state interfaces during battery discharge. Using X-ray tomography, cryo-focused ion beam/SEM, and finite-element modeling, we show that metal alloy interfacial layers can improve lithium evolution and mitigate contact loss. X-ray tomography is further shown to be particularly useful in observing the dynamic evolution of lithium metal, including void formation and filament growth. The second part of the talk focuses on alloy anodes. Alloy anodes typically exhibit fast capacity decay in lithium-ion batteries because of excessive solid-electrolyte interphase growth. We show that alloy anodes in solid-state batteries can exhibit improved interfacial stability and enhanced cyclability, and we present a new design for dense foil alloy anodes that can reduce manufacturing costs. Taken together, these findings show the importance of controlling chemo-mechanics and interfaces in solid-state batteries for improved energy storage capabilities.

Matthew McDowell is Associate Professor and Carter N. Paden, Jr. Distinguished Chair for Innovation in Materials Science and Metals Processing at Georgia Tech, with appointments in the Woodruff School of Mechanical Engineering and the School of Materials Science and Engineering. He received his Ph.D. from Stanford University in 2013 and was a postdoc at Caltech from 2013 until 2015. McDowell has received numerous awards, including the Presidential Early Career Award for Scientists and Engineers (PECASE), Sloan Fellowship, NSF CAREER Award, the ECS Battery Division Early Career Award, and Georgia Tech’s Outstanding Achievement in Early Career Research award. For more information, see https://mtmcdowell.gatech.edu.