Understanding the effect of PEMFC contamination from assembly aids materials: In-situ studies

Cost and durability issues of proton exchange fuel cell (PEMFC) systems can challenge the commercialization of fuel cells. Lowering the cost of PEMFC system components without compromising function, fuel cell performance, or life requires the understanding of contaminants that leach from the materials used in the system Balance of Plant (BOP) components and the effect of these contaminants on performance. This work seeks to identify and understand the impact of contaminants from materials that may be used as assembly aids with fuel cells. In this dissertation, data are presented from in-situ experiments designed to (1) screen potential materials for potential impact on PEMFC performance, (2) provide general guidance that may aid both system developers and material suppliers, and (3) understand the contamination phenomena. Correlations between the in-situ data and the chemical analysis of extracted solutions are presented.;After downselection of materials based on their chemical constituent analysis by GCMS, in-situ performance loss of PEMFCs exposed to leachates from an urethane adhesive was investigated. This adhesive is representation of most urethane materials because its leachate contains four chemical species found in the other adhesive through GC-MS analysis. Two levels of typical operating conditions (i.e, relative humidity, operating cell current and cell temperature) were studied for two levels of leach rate which was specified as feed rate of the assembly aids material. Performance loss at a fixed leach rate was less severe at higher relative humidity, cell current and cell temperature. Since each material may leach a mixture of organic compounds found by GS-MS analyses of these organics, in-situ performance data are presented for the four compounds that represent the constituents of an Urethane based assembly aids. Mixtures of these compounds for a given level of TOC were also studied. Ex-situ bekktech in-plane conductivity, ion-exchange isotherm and adsorption isotherm by rotating disk electrode method were used to explain the in-situ single cell voltage and conductivity losses. A quantitative analysis of performance loss and self induced recovery was also conducted to characterize the in-situ performance effect. Performing in-situ, ex-situ and quantitative characterization it is found that aromatic compounds are more strongly adsorb than their aliphatic counterpart. The results show that mixture of compounds may have different contamination and recovery effect than individual compounds and interaction between compounds may occur during fuel cell conditions. Parent Leachate containing these compounds shows the combined effect of the individual compounds.