Session: Rising Stars of Mechanical Engineering Celebration & Showcase

Paper Number: 149715

149715 - Linking Structure to Function at Electrochemical Interfaces: Li-Ion and Beyond 

Lithium batteries are expected to enable high energy density applications in electrified transportation and grid storage. However, lithium metal components suffer from severe interfacial instabilities, leading to efficiency losses and serious safety concerns. In the region between the negative electrode and the liquid electrolyte, a solid electrolyte interphase (SEI) is produced by the spontaneous breakdown of electrolyte compounds. The SEI in lithium metal batteries is hypothesized to play a key role in lithium deposition but is challenging to assess with traditional materials characterization methods. Despite the fact that the SEI on Li metal was described 45 years ago, it is still the only aspect of the battery that has ambiguity in function. As a community, we have struggled to establish structure-property-performance relationships for the SEI because it is a nanoscale composite that contains chemical compounds whose properties deviate from their bulk counterparts. To bridge this gap in characterization, we use nuclear magnetic resonance (NMR) spectroscopy to probe the structure and dynamics of interfacial phenomena in Li-ion and beyond Li-ion batteries and correlate these features with battery performance. In particular, we focus on the use of NMR to quantify the source of Li inventory loss, the mechanism of transition metal dissolution, structural evolution at the electrode/electrolyte interface, and the function of the SEI.

Insight from these methods allow us to determine the precise mechanisms of failure that arise inside of functional devices as well as develop new approaches to mitigate performance decline. We present evidence that cathode selection in Li batteries is critical to controlling Li deposition morphology. In addition, the nucleation and growth of select inorganic compounds in the SEI is key to controlling Li transport to/from the electrode surface due to changes in local ion coordination structure. Assignment of the interfacial chemistries and transport phenomena that dictate the formation of electrochemically inactive Li allows us to describe, at the molecular-level, the chemical mechanisms underpinning Coulombic efficiency and other performance metrics in Li batteries. Importantly, we also find that these design principles translate to beyond Li chemistries, provided that the reactivity of the system is well understood. Both Na and K improve the hydrolytic stability of the counteranion in electrolyte salts, preventing the formation of highly fluorinated interphases at low potential. We find that conventional surface characterization tools may disrupt the delicate SEI and lead to erroneous compositional results, requiring the use of less destructive techniques to guide the design of next generation electrolytes and electrode surfaces.

Presenting Author: Lauren Marbella Columbia University

Presenting Author Biography: Lauren Marbella is an Associate Professor in the Department of Chemical Engineering at Columbia University. Her research group focuses on understanding the relationship between electrochemical performance and interfacial chemistry in devices for energy storage and conversion. Marbella’s research has received numerous awards including the ACS Materials Au Rising Stars in Materials Research Award (2022), Cottrell Scholar Award (2022), the National Science Foundation (NSF) Faculty Early Career Development (CAREER) Award (2021), and the Scialog Collaborative Innovation Award for Advanced Energy Storage (Sloan Foundation, 2019).
She received her PhD in chemistry from the University of Pittsburgh in 2016, under the direction of Prof. Jill Millstone. In 2017, she was named a Marie Curie Postdoctoral Fellow at the University of Cambridge in the group of Prof. Clare Grey. There, she was also named the Charles and Katharine Darwin Research Fellow, which recognizes the top junior fellow at Darwin College at the University of Cambridge. She joined the chemical engineering faculty at Columbia University in 2018.

Authors:

Lauren Marbella Columbia University