Ion‐conduction of lithium fluoroalkylsulfonates in oligo(oxyethylene)‐branched poly(phosphazene)

Novel organic‐soluble lithium salts, lithium 1,1,2‐trifluoro‐4‐methoxy‐1‐butanesulfonate (I) and lithium 3‐(2‐methoxyethoxy)‐1‐propanesulfonate (II), were synthesized. Their ionic conductivities were examined in a solid polymer matrix of endo‐methoxy oligo(oxyethylene)‐branched poly(phosphazene) (III) and compared with the ordinary hybrids of LiCIO4/III or LiSO3CF3/III. The ionic conductivity of I/III hybrid was as high as 2,2.10−5 S. cm−1 at 25°C, which is comparable to that of LiCIO4/III or LiSO3CF3/III hybrids. Although anions are the major carrier ions in the LiCIO4/III or LiSO3CF3/III hybrids, the lithium transport number of I/III hybrid was about 0.5 due to the larger size of the counter anion.