Project Info
Investigating ion transport in lithium-ion battery electrolytes via advanced pulsed field gradient and electrophoretic NMR modalities
David Halat
david.halat@mines.edu
Project Goals and Description:
Understanding the mechanisms of ion transport within lithium-ion battery electrolytes is crucial to improving battery performance and minimizing degradation, leading to longer lifetimes. Our group is a pioneer in the development of electrophoretic nuclear magnetic resonance (NMR), a novel technique capable of independently resolving the mobilities of ions within battery electrolytes. Lithium fluoride is a commonly found degradation product in lithium-ion batteries and forms a significant component of the solid electrolyte interphase (SEI) that develops on battery electrodes. The SEI plays a crucial role in the performance and longevity of batteries, influencing factors such as capacity retention and cycling stability. Improving our fundamental understanding of how lithium fluoride and similar compounds are transported within the electrolyte is vital for modeling battery performance and degradation processes.
Despite the critical role of ion transport in battery performance, outstanding gaps exist in our fundamental understanding of ion transport processes, even for relatively simple systems. Traditionally, ion dynamics have been assessed indirectly through electrochemical methods, which often provide limited insights, as these techniques provide bulk, macroscopic information. In contrast, the in-situ eNMR spectroscopic methodology employed herein, using 7Li and 19F NMR to independently track the contributions of cations and anions, will allow for a much more direct and detailed examination of how different ions contribute to electrolyte conductivity. Moreover, NMR approaches can resolve local phenomena such as ion–ion and ion–solvent interactions and couple these to the electrophoretic mobilities measured by eNMR, tying together structure and function.
By varying the size, composition, and chemistry of the anion, as well as probing a variety of solvents and performing measurements as a function of electrolyte concentration, we will investigate the factors that contribute to Li+ transport and ultimately optimize electrolyte performance. Lithium fluoride presents a particularly intriguing case study, as the smaller size of the fluoride ion as compared with much more common anions like PF6- or TFSI- will offer unique insights into ion pairing effects on Li+ transport, and contribute to our knowledge of the mechanisms behind SEI formation and battery degradation. Ultimately, this research will contribute towards the development of longer-lasting energy storage devices.
More Information:
Grand Challenge: Engineer the tools of scientific discovery.
Primary Contacts:
David Halat, david.halat@mines.edu
Student Preparation
Qualifications
Student should possess foundational understanding of chemistry, particularly in the areas of physical chemistry and materials science.
Prior experience with laboratory techniques, especially in handling chemicals and preparing solutions.
Familiarity with glovebox handling and operation is required, particularly in the latter stages of the project (many battery electrolytes are air or water sensitive).
Basic knowledge of NMR principles and techniques, while not compulsory, would be highly beneficial.
Student should possess strong analytical skills, attention to detail, and the ability to work independently as well as collaboratively within a research team.
TIME COMMITMENT (HRS/WK)
4-5
SKILLS/TECHNIQUES GAINED
Electrolyte formulation - student will learn how to prepare and formulate electrolyte solutions with various lithium salts, including lithium fluoride, and how to handle and characterize these materials appropriately
Glovebox handling - the student will refine their skills in working within a glovebox environment, crucial for handling air-sensitive materials and preparing
NMR techniques - the student will gain hands-on experience with both solution and solid-state NMR, including routine 7Li and 19F experiments to probe ion interactions within the electrolyte, Pulsed Field Gradient (PFG) NMR to measure diffusion coefficients and study ion transport dynamics, and electrophoretic NMR as a probe of ion migration in an electric field, providing insights into ion transport mechanisms.
Data analysis and interpretation - the student will learn how to analyze NMR spectra, extract relevant parameters such as activation energies and diffusion coefficients from variable-temperature PFG data, and compare these results with existing literature. This will involve developing skills in data processing software and statistical analysis.
Literature review and scientific writing - the student will become proficient in reviewing and analyzing the relevant scientific literature to contextualize their findings, as well as developing their scientific writing skills by contributing to the preparation of manuscripts for publication.
Research presentation skills - the student will have the opportunity to present their research findings in group meetings and potentially at conferences, honing their ability to communicate scientific results effectively.
MENTORING PLAN
Mentoring plan includes the following elements that are targeted at ensuring their academic and professional development with a view to future success within graduate school:
One-on-one training -- personalized, hands-on training, particularly at the NMR spectrometer, with both the PI and graduate students, involving guided practice to build proficiency in advanced NMR techniques, including PFG NMR, and electrophoretic NMR, with a view towards building independence in running complex experiments.
Regular meetings, goal-setting - weekly or bi-weekly meetings will be scheduled to discuss progress, troubleshoot any issues, and set short- and long-term goals, particularly towards the beginning and end of the project related to initial literature review and final project reporting, respectively. The student will have ample opportunities to ask questions, receive feedback, refine their approach to the research, and engage with other group members. Writing and presentation development involves two areas, namely:
(1) Literature review - student will be guided in reviewing and understanding key literature in the NMR and battery community, with direct relevance to the project. The student will develop critical thinking skills and a deeper understanding of the field.
(2) Research manuscripts - The student will receive mentorship in scientific writing, with a goal to write up their results in a relevant journal. Additionally, they will be coached on how to effectively present their research findings to both specialized and general audiences.
Establishing research independence - mentoring approach will gradually shift from close supervision to fostering the student's ability to conduct independent research with the expectation to carry out advanced NMR experiments and data analysis with minimal supervision.
Career and grad school prep – regular discussions will be held to explore the student’s career aspirations, with a focus on preparing for graduate school applications. This will include advice on selecting programs, preparing application materials, and developing a research portfolio.
Integration into the research community - the student will be encouraged to engage with the broader research community at Mines by attending group meetings including in other relevant groups and meeting with the broader battery and spectroscopy community, particularly outside the student’s home department. Networking opportunities will be provided to help the student build professional connections within the field.
Preferred Student Status
Junior
Senior