Four different kinds of Li salts were complexed with poly(ethylene oxide) membranes plasticized by succinonitrile (SN). Plasticizing effects were reflected by ionic conductivities enhancement. The high ionic conductivities can be attributed to the high free carrier concentration because of the high polarity and diffusivity of SN, decreased crystallinity of polymer and dissociable Li salt. Moreover, the membranes still preserved high mechanical strength. The combination of enhanced mechanical and electrical properties renders the electrolyte a potential candidate in Li-ion polymer batteries. (C) 2008 Elsevier B.V. All rights reserved.