Phase Behavior and Electrochemical Characterization
of Blends of Perfluoropolyether, Poly(ethylene glycol), and a Lithium
Salt
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Abstract
Electrolytes
consisting of low molecular weight perfluoropolyether
(PFPE), poly(ethylene glycol) (PEG), and lithium bis(trifluoromethanesulfonyl)imide
(LiTFSI) blends were prepared and systematically studied for salt
concentration and stoichiometry effects on the materials’ thermal
and electrochemical properties. Herein we report that the tunable
ratios of PFPE and PEG allow for precise control of crystalline melting
and glass transition temperature properties. These blended liquid
polymer electrolytes are inherently nonflammable and remain stable
in the amorphous phase from approximately 150 °C down to −85
°C. The ionic conductivity of the electrolytes are on the order
of 10<sup>–4</sup> S/cm at 30 °C, which makes them suitable
for rechargeable lithium batteries
