Conductivity and Relaxation Phenomena in Proton and Anion Exchange Membranes by Broadband Electric Spectroscopy

Understanding of the relationship existent between structure and ion conduction mechanisms is crucial in order to trigger the development of new high performing proton and anion conducting membranes for applications in fuel cells [1]. It has been suggested that conductivity in ion conducting materials occurs via a number of different processes. The main conductivity processes are correlated to: a) the charge migration events of ions between coordination sites in the host materials; [2-5] and b) the relaxation phenomena involving the dynamics of the host materials [2-5]. Ions “hopping” to new chemical environments can lead to successful charge migration only if ion-occupying domains relax via reorganizational processes [2-5], which are generally coupled with relaxation events associated with the host matrix. A useful technique to study and understand ion conducting mechanisms and to correlate this to the morphology of the electrolytes is Broadband Electric Spectroscopy (BES). In this presentation, an overview of the application of BES in the study of the charge transfer mechanisms in pristine and hybrid inorganic-organic proton-conducting and anion-conducting membranes is provided. Furthermore, the models adopted for the interpretation of BES results as well as some case studies of conductivity mechanisms are elucidated. Acknowledgements: The authors thank the StrategicProject “From materials for Membrane electrode Assemblies to electric Energy conversion and SToRAge devices” (MAESTRA) of the University of Padova for funding this activity. References [1] Polymer Electrolytes: Fundamentals and Applications; Sequeira, C.; Santos, D., Eds.;Woodhead Publishing Limited: Oxford, 2010. [2] Di Noto, V. J. Phys. Chem. B,104 (2000) 10116-10125. [3] Di Noto, V.; Vittadello, M.; Lavina, S.; Fauri, M.; Biscazzo, S. J. Phys. Chem. B,105 (2001) 4584-4595. [4] Di Noto, V. J. Phys. Chem. B,106 (2002) 11139-11154. [5] Di Noto, V.; Vittadello, M.; Greenbaum, S. G.; Suarez, S.; Kano, K.; Furukawa, T. J. Phys. Chem. B, 108(2004) 18832-18844.