Perfluoropolyether-based Electrolytes for Lithium Battary Applications

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  • March 19, 2019
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  • Wong, Hiu Ching
    • Affiliation: College of Arts and Sciences, Department of Chemistry
Abstract
  • Large-scale rechargeable batteries are expected to play a key role in today's emerging sustainable energy landscape. State-of-the-art lithium-ion batteries are not only widely used in electric vehicles, but they are currently gaining traction as backup power in aircraft and smart grid applications. In all of these cases, safety surrounding the electrolyte, an essential component of a lithium-ion battery, is a challenging limitation: the low flash points of currently used small molecule organic alkyl carbonates impose a high risk of ignition under most operating conditions. For this reason, extensive efforts are being made to develop viable nonflammable electrolytes to replace these organic solvents. Herein, we describe new classes of nonflammable liquid and solid electrolytes composed of oligomeric perfluoropolyethers. These materials are promising electrolyte alternatives due to their low glass transition temperatures, high chemical stability, capacity to dissolve lithium salts such as lithium bis(trifluoromethane)sulfonimide lithium salt, and compatibility with various common polymers such as poly(ethylene glycol). Synthetic modifications used to introduce a wide range of functional groups has created a platform of intrinsically fireproof materials that can be chemically tailored to achieve the desired physical, thermal, mechanical, and electrochemical properties for specific battery applications. Using this approach carbonate-, thiol-, allyl-, and propargyl- functionalized perfluoropolyethers were prepared from the commercially available hydroxyl-terminated PFPEs. The terminal group and molecular weight effects on the bulk properties of these materials were systematically characterized and their viability as electrolytes was evaluated. The described work ultimately paves the way towards further optimization of perfluoropolyether materials towards the development of high performance lithium- ion batteries. The interesting properties of these materials invite an extensive study into the fundamental mesoscale ion transport and the relationship between perfluoropolyether chemical structure and electrolyte electrochemical property, as well as a closer analysis into the perfluoropolyether and electrode interface. Investigation in these areas using techniques such as advanced nuclear magnetic resonance spectroscopy and transmission electron microscopy is proposed.
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  • In Copyright
Advisor
  • DeSimone, Joseph M.
  • Ashby, Valerie
  • Sheiko, Sergei
  • Gagne, Michel
  • Murray, Royce W.
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2015
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  • Chapel Hill, NC
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  • There are no restrictions to this item.
Date uploaded
  • June 23, 2015

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