Ion-conducting polymeric membranes for electrochemical energy devices

The improvement, in terms of cost, durability and performances, of fuel cells and redox flow batteries seems fundamental for the future. Among the issues affecting these devices, the performance and the durability of the solid electrolyte based on a synthetic membrane, if considering polymer electrolyte membrane (PEM) devices, is challenging. The research objective of this PhD thesis is the development and investigation of new polymer electrolytes to be easily casted in membrane shape and capable to attain a good ionic conductivity, selectivity and stability. The approach consists not only in changing the polymer skeleton (aromatic polymers like poly(etheretherketone) or polysulphone instead of perflorinated polymers), but also in changing the functional moieties (like sulfonic acid or secondary and tertiary amino groups to have protonic, anionic, or amphoteric conduction) and cross-linking the polymer. It was demonstrated that an enhancement of ion conductivity, stability in severe conditions, selectivity, and mechanical strength can be obtained and that the properties can be easily tuned. The results are promising for the application of these electrolytes in high technology storage and conversion devices.