ChE PhD Dissertation Defense: Benjamin Leifer

Name:
Benjamin Leifer

Title:
Electrolyte Design, Interfacial Stability, and Cell Scale-up for Low-Temperature Lithium-Ion Batteries

Date:
10/16/2026

Time:
12:00:00 PM

Committee Members:
Prof. Joshua Gallaway (Advisor)
Prof. Qing Zhao
Dr. Yunume Fitchrova
Prof. Juner Zhu

Location:
Ryder 233

Abstract:
Lithium-ion batteries supply energy for transportation and equipment that must operate across a wide range of environmental conditions. At low temperature, slower ion transport and electrode reactions increase polarization and reduce the capacity and energy available from the cell. Electrolyte design offers a route to improving cold operation, but useful liquid transport must be accompanied by stable and reversible reactions at both electrodes.

The low cost and freezing points of ether solvents make them particularly attractive as platforms for low-temperature batteries, but ether reactivity at the operating potentials of lithium-ion batteries hinders their adoption. Interphase-forming additives complement these transport properties by modifying electrode-electrolyte compatibility and subsequent charge storage. As cells are scaled up to application-relevant sizes, electrolyte inventory plays a key role in managing separator wetting and electrode access, also key determinants of low-temperature performance.

This dissertation examines how electrolyte composition, electrode passivation, and liquid inventory govern low-temperature battery performance. Mixtures of 1,2-dimethoxyethane and tetrahydrofuran are investigated across solvent ratios and lithium-salt concentrations using Raman and nuclear magnetic resonance spectroscopy, conductivity measurements, and electrochemical testing. The selected tetrahydrofuran-rich mixture retains higher conductivity than a conventional carbonate electrolyte at −40 °C, while increasing salt concentration strengthens Raman responses associated with solvent coordination and ion association. Fluoroethylene carbonate, vinylene carbonate, and their combination are then evaluated as electrolyte additives through graphite, positive-electrode, and full-cell comparisons. Additive incorporation, even in low amounts, improves electrode-electrolyte compatibility while retaining useful cold transport.

Finally, a separate study of methyl propionate/fluoroethylene carbonate examines electrolyte fill effects in large format 1 Ah pouch cells. Increasing fill reduces room-temperature polarization and improves low-temperature discharge capacity in the 1 Ah cells. At the selected fill, the prototype-scale 13 Ah cells deliver capacity and energy comparable to those of the control electrolyte. These findings establish a basis for selecting electrolytes through combined evaluation of cold transport, electrode compatibility, and electrolyte inventory in practical cell architectures.

Benjamin Henry Leifer is a PhD candidate in Chemical Engineering at Northeastern University, where he works with Professor Joshua W. Gallaway on lithium-ion batteries for cold environments. He grew up in Newton, Massachusetts, and earned his B.S. in Chemical Engineering from Washington University in St. Louis in 2016. Before joining Northeastern, he worked at Veloxint Corporation on alloy development for high wear and 3-D metal printing, and at Cabot Corporation on materials for lithium-ion batteries. His doctoral research examines how electrolyte chemistry and cell design influence battery performance in low-temperature lithium-ion batteries, from reactions at electrode surfaces to the operation of larger cells. Outside the lab, he can be found at various local parks with his wife, Miri, chasing after their two young children, Ike and Ruthie.