Lithium salts of bis(perfluoroalkyl)sulfonic acids: synthesis, characterization and conductivity studies

Abstract

Lithium salts of bis(perfluoroalkyl) sulfonic acids, (CF 2) n (SO 2OLi) 2 · wH 2O, where n = 1–4( 1–4), w = the number of waters of hydration, and O(CF 2CF 2SO 2OLi) 2 ( 5), were prepared by double decomposition and ion-exchange methods. Infrared, NMR and mass spectral data support the assigned structures. Thermal measurements indicate that these salts can be prepared free of acid and water impurities; the salts are stable up to 220 °C for the smallest anion, and above 400 °C for the largest anion. Impedance analyses were used to provide the bulk ionic conductivities of some poly (ethylene oxide)-salt complexes. Of these salts, 5 was found to have the highest conductivity: σ is about 5 × 10 −6 Ω −1 cm −1 at 100 °C.