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Tailored Quasi-Solid-State Lithium-Ion Electrolytes for Low Temperature Operations

Version 2 2023-12-11, 20:13
Version 1 2023-12-10, 22:22
thesis
posted on 2023-12-11, 20:13 authored by Nestor R LevinNestor R Levin

The thesis goal was to design a quasi-solid-state battery electrolyte, which was optimized to function at ambient as well as low temperatures. In the first project, an array of quasi-solid-state electrolytes were developed and compared. A series of electrochemical, spectroscopic, and thermal experiments in addition to imaging techniques determined a top performer as well as elucidated possible mechanistic explanations. This systematic study attempted to validate literature conclusions about the failure mechanisms governing batteries (solid-state batteries) at ultralow temperatures, while also offering hypothesis driven additional insight. The optimized electrolyte, which will be deemed as CSPE@2MMeTHF, performed well for several key reasons, traced to the co-solvent used (Me-THF), the salt concentration, and its formation of a stable and suitable cathode-electrolyte interphase. It was able to perform well at 25 °C, and down to -25 °C. The second part of the work, focused on further optimizing the electrolyte by removing a ‘polymer wetting/soaking’ step, removing a ceramic component, and pairing it with a recently discovered anodic electrode material. Given that narrowing the research gap for low temperatures requires both electrolyte and electrode design, it was important to consider this aspect of the problem as well. The cathodic electrode used for the first project, traditionally performs poorly at low temperatures, allowing for a suitable experimental control for the electrolyte. However, the new anodic electrode had two ways of storing lithium ions, as opposed to just one in the former, making it an attractive option for the stated goal of a low-temperature solid-state battery. This second project is akin to a ‘proof-of-concept’ work and there is much more room for further study, especially in preparing a full cell with the aforementioned electrodes cathode (LFP) and anode (NbWO) with the second SPE@51DMMeT electrolyte. In summary, this thesis shows method design to prepare solid-state electrolytes with portion of liquid, two successfully developed electrolyte systems for low temperatures, and a rigorous discussion of factors that affect electrochemical performance. Demonstrated research activities are of great value to defense as the current lithium-ion batteries does not perform well at subzero temperatures.

History

Degree Type

  • Master of Science

Department

  • Chemical Engineering

Campus location

  • West Lafayette

Advisor/Supervisor/Committee Chair

Vilas G. Pol

Additional Committee Member 2

Jeffrey Miller

Additional Committee Member 3

Eric Dietz

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