Solid polymer electrolytes from lithium (perfluorovinylether) sulfonate - Derived salts dissolved in high-molecular-weight poly(ethylene oxide)

Solid polymer electrolytes (SPEs) were prepared using new lithium salts derived from a lithium (perfluorovinylether)sulfonate (CF2=CFOCF2CF2SO3Li) coupled to either a partially fluorinated alcohol (monolithium series) or a partially fluorinated diol (dilithium series). High-molecular-weight poly(ethylene oxide) (PEO) was used as the polymeric host. SPE characterization was accomplished using modulated differential scanning calorimetry (MDSC), 1H and 19F NMR spectroscopy and electrochemical impedance spectroscopy (EIS). Ionic conductivities for SPEs made using the new salts, and also using lithium triflate (LiTf) and lithium bis[(trifluoromethyl)sulfonyl]imide (LiTFSI) as controls, were measured over a temperature range between 120 °C and room temperature for materials with an ethylene oxide to lithium (EO/Li) ratio of 30-1. Conductivities varied depending upon the structure of the alcohol or diol used to make the salt, and were generally higher for alcohols/diols having more perfluorinated methylene groups.