Transport properties of the solid polymer electrolyte system P(EO)(n)LiTFSI

Values for the lithium ion transference number (t(+)(0)) are reported for t he solid polymer electrolyte system poly(ethylene oxide) (PEO) complexed wi th Li(CF3SO2)(2)N (LiTFSI). t(+)(0),ranges from 0.17 +/- 0.17 to 0.60 +/- 0 .03 in the salt concentration (c) region of 742 to 2982 mol/m(3) at 85 degr ees C. The concentration dependence of t(+)(0) and the molar ionic conducti vity (Lambda) are shown to be in good agreement with a free volume approach over the salt-rich composition range investigated. The present t(+)(0) res ults were obtained using an electrochemical technique based on concentrated solution theory. This experimentally straightforward method is herein demo nstrated to give accurate results for a highly concentrated SPE system, wit hout relying on any dubious simplifications regarding the state of the elec trolyte.