Effects of contaminant on thermal properties in perfluorinated sulfonic acid membranes

The influence of controlled cationic contaminant on the thermal behaviour of proton conducting perfluorosulfonic acid membrane (PFSA) was studied. A series of Ni2+-exchanged membrane was prepared by varying the ratio between positive charges resulting from the contaminant to the negative charges originating from the sulfonate groups. A large change in properties was evidenced at a ratio close to 0.2. Above this threshold, the PFSA exhibited significantly higher main relaxation and degradation temperatures. The set of experimental data could be described with the help of a phenomenological microstructural model essentially based on ionic interactions. The impurity model could then be employed to understand changes in protonic conductivity from the literature.

Figure optionsDownload high-quality image (134 K)Download as PowerPoint slideResearch highlights▶ Contamination of PFSA with ionic cations is detrimental to fuel cell performances. ▶ Performances depend on number of cations regardless of the exposure concentration. ▶ Cationic contamination of PFSA membrane is a cumulative process. ▶ Loss of properties follows a s-shaped curve with a well-defined threshold.