Ionic conductivities of polymeric solid electrolyte films containing rare earth ions

Abstract

Polymeric solid electrolyte films containing rare earth metal ions (Ce3+, La3+, Yb3+) have been prepared, with a view to applying them to solid-state electrochemical devices. The films, composed of poly(ethylene oxide)-grafted poly(methylmethacrylate) (PEO–PMMA), were prepared by dissolving rare earth salts with appropriate amounts of poly(ethylene glycol) dimethyl ether (PEG) that have ethylene oxide units in their structure. The ionic conductance behaviour of the polymeric composite electrolyte systems was investigated by AC impedance and DC polarization methods in an ambient temperature range. The oligo(ethylene oxide) units in the polymer matrix and the PEG components ensured the dissociation of the salts and the high mobility of the resulting ionic species in the solid films. About 10−5 S cm−1 or above of ionic conductivity was obtained for a PEO–PMMA/PEG/Ce(ClO4)3 system at room temperature. The addition of a liquid plasticizer in the composite improved the conductivity by about two orders of magnitude.