The Effect of Calcium and Sodium Deposition in A Pemfc

Even in low temperature fuel cell such as the Proton Exchange Membrane Fuel Cell (PEMFC) contaminants from bi-polar plates, sealants, and gaskets can leach into the membrane. Here a study of two ions is presented because these ions, sodium and calcium, are of interest as materials are developed. This study was focused on whether the ions deposit on the sulfonic sites within the membrane electrode assembly and on whether equal normality poisonings of sodium and calcium (5 mM and 2.5 mM) would produce the same percentage of performance loss. The results indicate that performance as measured by initial current loss for both poisonings was 45 %. After a 48 hour period of constant voltage, the sodium poisoned cell recovered (to around 17 % degradation) while the calcium degradation recovered only to 25 %. Ex-situ experiments are discussed and electron microscope results illustrate cationic buildup mainly around areas of high sulfur concentration supporting our theory of the location of cationic buildup. Future work should determine if the results can be generalized to all monovalent and divalent cations.