Collaborative Research: Characterization of Transport Properties and Microstructures of Battery Electrolytes via In Situ Spectroscopy

With the support from the Electrochemical Systems program in the Division of Chemical, Bioengineering, Environmental, and Transport Systems, the investigators will develop innovative in situ techniques to characterize the liquid electrolyte for rechargeable batteries. Rechargeable batteries are one of the most popular energy storage devices for electronic products, electric vehicles, and grid energy storage.

The next generation of rechargeable batteries requires excellent performance in terms of fast charging and safety. This work will provide universal methods to characterize the transport property and microstructure of the electrolyte crucial to battery performance. The investigators will incorporate the battery research into their teaching curricula for undergraduate and graduate students, encourage students from underrepresented groups in STEM to participate in the research, and broaden the impact of the research through outreach activities, e.g., workshops with local school teachers on K-12 science education.

The primary objectives of this work are to develop a variety of universal in situ techniques to characterize the transport property and microstructure of battery electrolytes, including in situ probe beam deflection (PBD), in situ small-angle X-ray scattering (SAXS), ohmic microscopy, and microelectrode array. Specifically, in situ PBD will be employed to measure the transference number and diffusivity in the framework of concentrated solution theory.

It only requires one experiment to determine the transference number and diffusivity of the electrolyte, while traditional methods will require the combination of three or four electrochemical experiments. In situ PBD can also monitor the ionic concentration profile of the electrolyte in an operating battery. In situ SAXS will be used to characterize the microscopic structure of the concentrated electrolyte and monitor the variation of ion pairs and/or aggregates induced by the electric field.

Ohmic Microscopy will be utilized to measure the conductivity and monitor the variation of electrolyte conductivity resulting from the charge separation induced by the strong electric field. A microelectrode array will be used to measure the ionic concentration and diffusivity of the electrolyte simultaneously. The other complementary techniques, including Raman spectroscopy and molecular dynamics simulation, will provide a molecular-level understanding of the correlation between the microstructure and transport property.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.