The Department of Chemical and Biological Engineering is pleased to present a seminar by department faculty member Jeff Lopez, titled:
Interfacial Reaction Mechanisms Toward Precision Engineering of Interphase Chemistry in Next-Generation Batteries
Research in the Lopez Group aims to build fundamental understanding to control reactions and interactions at electrochemical interfaces. We work to apply this understanding to develop materials and processes that improve the energy density, reduce costs, and improve the sustainability of the batteries that power electric vehicles and enable renewable energy generation on the grid. At the heart of every battery is an ionically conductive but electronically insulating electrolyte that dictates the safety, charge rate, and cycling lifetime of the device. Furthermore, for every new battery technology, a new electrolyte must be identified and optimized so that it is compatible with the desired electrode components.
Electrolyte decomposition is engineered to produce stabilizing interphases that kinetically passivate electrode surfaces, but the mechanisms to form these interphases and their ideal microstructure and composition are not well understood. In this presentation, I will discuss recent progress in our group toward improving the precision with which interphases can be designed to enable high energy density and low cost storage. First, I will detail our group’s efforts to better understand electrolyte reaction mechanisms that initiate and propagate organic SEI matrix growth. I will discuss the development of spin trapping to stabilize radical intermediates in electrolyte reduction pathways to clarify reaction mechanisms. Through this approach, we have confirmed a ring opening mechanism for fluoroethylene carbonate (FEC) reduction and the reduction of 1,1,2,2-tetrafluoroethyl 2,2,3,3-tetrafluoropropylether (TTE) into vinyl monomers that protect inorganic interphase components. Second, the kinetic competition between electrolyte components influences the composition of the organic phase of the SEI. We have used operando FTIR to identify how lithium hexafluorophosphate (LiPF6) modulates the competition between FEC and lithium bis(fluorosulfonyl)imide (LiFSI) during interphase formation, and we have used quantitative measurements of selectivity to anion decomposition to develop a framework for estimating the solvent vs anion selectivity in interphase formation. Together, these results build toward a more detailed understanding of critically important interphase chemistry. With a comprehensive view of reaction mechanisms and kinetics, new opportunities will arise for precise design and control of the interphase in next generation batteries.
Jeffrey Lopez is an Assistant Professor of Chemical & Biological Engineering at Northwestern University. His research is focused on using fundamental chemical engineering principles to study energy storage devices and design solutions to enable accelerated adoption of sustainable energy technologies. Jeffrey is an expert in the study of charge transport processes and reactions at electrochemical interfaces to inform the design of new materials for energy storage applications. Recently, his group is working to discover new electrolytes for high energy density battery chemistries, to develop new materials and processes for more sustainable and circular battery manufacturing, and to leverage automated experimentation and high throughput analysis to accelerate the process of materials discovery and development. Jeffrey has received multiple awards for his research including the ECS Toyota Young Investigator Fellowship in 2025 and the NSF CAREER Award in 2024. Prior to joining the Northwestern faculty, Jeffrey was an Intelligence Community Postdoctoral Fellow at the Massachusetts Institute of Technology and a NSF Graduate Research Fellow at Stanford University where he completed his PhD in Chemical Engineering. Jeffrey received his B.S. in Chemical Engineering from the University of Nebraska – Lincoln.
Cost: Free
Olivia Wise
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