Project Info
Speciation and ion transport of lithium fluoride and SEI components in battery electrolytes via advanced NMR spectroscopy
David Halat
david.halat@mines.edu
Project Goals and Description:
This research project explores how lithium fluoride (LiF), a major degradation product and solid electrolyte interphase (SEI) component in rechargeable lithium-ion batteries, affects ion transport and speciation in battery-relevant electrolytes. Through advanced 7Li and 19F NMR techniques, including pulsed field gradient (PFG) and electrophoretic NMR, we aim to quantify lithium and fluoride ion mobility across a variety of chemical environments.
This study will target three major research directions:
LiF vs. other degradation products: We will compare LiF to other common inorganic SEI products such as lithium carbonate (Li2CO3) and lithium oxide (Li2O), examining how these species influence lithium-ion mobility and solution conductivity. This comparison will reveal how ion transport is modulated by different degradation or passivation compounds formed at the battery–electrolyte interface.
LiF additions to organic electrolytes: How does addition of LiF to common organic electrolytes (e.g. LiPF6 in EC:DMC) influence conductivity, ion speciation, and degradation behavior? This reflects early stages of SEI development and uncovers how LiF accumulation in bulk electrolyte affects lithium-ion transport and overall cell performance.
Temperature-dependent transport: using variable-temperature NMR and conductivity probes, we will extract activation energies for lithium and fluoride mobility under controlled electrolyte conditions. These data will be compared across solvents, concentrations, and additive conditions, helping to link speciation and structure to transport efficiency.
Complementary studies will focus on pH-dependent fluoride speciation, using 19F NMR to track the equilibrium between fluoride ion (F⁻) and hydrofluoric acid (HF), and incorporating trifluoroacetic acid (TFA) as an internal 19F reference and titration agent; ultimately, this work will inform the design of more robust electrolytes and better interfacial layers by clarifying the role of LiF and related species in controlling transport and degradation in lithium-ion batteries.
More Information:
Grand Challenge: Engineer the tools of scientific discovery.
Im, J.; Halat, D. M.; Fang, C.; Hickson, D. T.; Wang, R.; Balsara, N. P.; Reimer, J. A. Understanding the Solvation Structure of Li-Ion Battery Electrolytes Using DFT-Based Computation and 1H NMR Spectroscopy. J. Phys. Chem. B 2022, 126 (47), 9893–9900. https://doi.org/10.1021/acs.jpcb.2c06415.
Hickson, D. T.; Im, J.; Halat, D. M.; Karvat, A.; Reimer, J. A.; Balsara, N. P. Low-Temperature Characterization of a Nonaqueous Liquid Electrolyte for Lithium Batteries. J. Electrochem. Soc. 2024, 171 (3), 030514. https://doi.org/10.1149/1945-7111/ad2d91.
Primary Contacts:
David Halat, david.halat@mines.edu
Student Preparation
Qualifications
Coursework in general and physical chemistry; prior experience with laboratory solution preparation; familiarity with glovebox handling and NMR helpful but not required; strong analytical skills and interest in energy storage or spectroscopy
TIME COMMITMENT (HRS/WK)
4-5
SKILLS/TECHNIQUES GAINED
Formulation and handling of aqueous and organic battery electrolytes; air-free sample preparation using a glovebox; hands-on use of 7Li and 19F NMR, including PFG and electrophoretic NMR; variable-temperature measurements of conductivity and diffusivity; interpretation of chemical shifts, speciation, and ion transport properties; exposure to SEI component behavior and degradation pathways; scientific writing, presentation, and critical literature review skills
MENTORING PLAN
Individual training on NMR instrumentation and glovebox handling from the PI and experienced group members; weekly meetings to discuss data, plan experiments, and troubleshoot methods; guided literature reading on SEI chemistry, ion transport, and NMR methods; writing and presentation development, including opportunities to contribute to manuscripts or present at undergraduate research events; graduate school mentorship, including support for application materials and identifying suitable programs; community integration through interactions with researchers in electrochemistry, materials science, and analytical chemistry
Preferred Student Status
Junior
Senior