Charge transfer mechanisms in Anionic Membranes by Broadband Electric Spectroscopy

Anionically conducting materials (ACMs) are of great importance for the fabrication of alkaline fuel cells. It has been suggested that conductivity in ACMs occurs via a number of different processes. The predominant conductivity processes are attributed to: (a) the migration of anions between coordination sites in the host materials, and (b) the increase of conductivity due to relaxation phenomena involving the dynamics of the host materials. Hopping of anions to new chemical environments can lead to successful charge migration only if anion-occupying domains relax via reorganizational processes, which in general are coupled with relaxation events associated with the host matrix. In this presentation, the instruments used in the comprehensive study of the electric response of ACMs are described, and the basic tools to understand broadband electric spectroscopy are provided. The first part of the presentation reviews the general phenomena and the basic theory underlying each type of electric response that materials may exhibit when they are subjected to static or dynamic electric fields. Afterwards, the strategies of data analysis, which is accomplished using specific empirical or theoretical models, are described in detail. The final part of the presentation discusses the methodologies for accurate data collection.