Solid polymer electrolytes based on nanocomposites of ethylene oxide–epichlorohydrin copolymers and cellulose whiskers

With the aim of developing ion‐conducting solid polymer electrolytes that combine high ionic conductivity with good mechanical properties, we prepared and investigated nanocomposites of LiClO₄‐doped ethylene oxide‐epichlorohydrin (EO‐EPI) copolymers and nanoscale cellulose whiskers derived from tunicates. We show that homogeneous nanocomposite films based on EO‐EPI copolymers, LiClO₄, and tunicate whiskers can be produced by solution‐casting THF/water mixtures comprising these components and subsequent compression‐molding. The Young's moduli of the nanocomposites thus produced are increased by a factor of up to >50, when compared to the copolymers, whereas the electrical conductivities experience only comparably small reductions upon introduction of the whiskers. The nanocomposite with the best combination of conductivity (1.6 × 10^?4 S/cm at room temperature and a relative humidity of 75%) and Young's modulus (7 MPa) was obtained with a copolymer having an EO‐EPI ratio of 84 : 16, a whisker content of 10% w/w, and a LiClO₄ concentration of 5.8% w/w. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2883–2888, 2004