The Effect of Common Airborne Impurities and Mixtures on PEMFC Performance and Durability

Abstract

The effect of exposing the cathode of hydrogen (H 2 ) proton exchange membrane fuel cells (PEMFCs) to the airborne contaminants: sulfur dioxide (SO 2 ), benzene (BZ), and nitrogen dioxide (NO 2 ) on their performance and durability was studied for individual contaminants and mixtures at a total concentration of two parts per million (ppm). The goals were to characterize the effects of contaminant exposure on the: (i) cell performance, (ii) ability of the fuel cell to recover performance using only pure air, (iii) irrecoverable performance loss, and (iv) changes to the durability of the fuel cell as quantified by changes to the electrochemically active surface area (ECSA) of the electrodes. In general, contaminant mixtures decreased performance more than single contaminants. Performance loss was recoverable with pure air when no SO 2 was in the stream and incomplete when it was. Contaminant exposure generally accelerated ECSA loss. IntroductionContaminants present in the air of the oxidant stream of PEMFCs can cause significant performance loss, which can be irreversible in some cases (1). This is an important consideration for developing PEMFCs for commercial applications because airborne contaminants can arise from many different sources including polluted air, geological emissions, and off-gassing from unstable compounds. Thus, the performance of the fuel cell can be affected in unknown ways depending on the quality of the local air (2). It is therefore important to study the effects of contaminants on performance and durability so that the operational lifetime of the PEMFCs can be maximized to facilitate full-scale commercialization and deployment of these devices.The Hawaii Natural Energy Institute (HNEI) is currently researching the performance effects of a number of airborne contaminants and developing strategies to mitigate resulting performance losses through two different projects funded by the United States' Department of Energy (DOE) and the Office of Naval Research (ONR). The details of the DOE effort have been described in several publications and have been large in scope identifying seven critical airborne contaminants from an initial list of 260 (2-4). The DOE sponsored research has focused largely on single contaminants and has identified several important mechanisms for each contaminant that contributes to performance loss ECS Transactions, 64 (3) 773-788 (2014) 773 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 131.211.208.19 Downloaded on 2015-03-13 to IPThe work presented here is supported by the ONR as part of their goal to deploy fuel cells under a wide range of operating environments including battlefield conditions and regions outside of the United States, which may have poor air quality. The contaminants studied here are SO 2 , NO 2 , and BZ and are different from those in the DOE project to avoid duplicating efforts. Additionally, this work investigates how contaminant mixtures affect performance and durabili...

Study of the aromatic hydrocarbons poisoning of platinum cathodes on proton exchange membrane fuel cell spatial performance using a segmented cell system

“…Injection of 2 ppm benzene into the air stream led to a decrease in cell and segment voltage. At steady state, the voltage losses were 40-45 and 100-110 mV at 0.2 and 1.0 A cm 2 , respectively, in agreement with results published in a few other studies [15,27]. The observed performance drop was accompanied by a current density redistribution, which likely depended on the operating current and revealed different behavior patterns.…”

“…Extensive research efforts have been dedicated to examining PEMFC cathode contamination caused by inorganic pollutants such as SO2 [3,[6][7][8][9][10][11][12][13][14][15], NOx [3,7,8,11,12,[14][15][16][17][18], NH3 [7,8,11,13,19,20], H2S [7,8,11,12,21] and Cl - [13,[22][23][24][25][26]. However, studies on the effects of organic compounds such as air contaminants are smaller in scope and limited by benzene [15,27,28], 1,3-butadiene [28], toluene [29,30] and chemical warfare agents [27]. Because organic compounds have the potential to decrease PEMFC performance, a list of 260 possible airborne contaminants provided by the Environmental Protection Agency has been evaluated.…”

“…The adsorption of benzene and its derivatives onto Pt has been a subject of fundamental studies due to considerable interest in various electrochemical syntheses involving aromatic hydrocarbons and for the purification of effluent from organic contaminants [42][43][44][45][46][47][48][49][50][51]. However, data concerning the effects of benzene and naphthalene on PEMFC performance and oxygen reduction are rare [15,27,35]. It was shown that even 2 ppm of C6H6 in air caused a fuel cell performance loss of ~150 mV at 1.0 A cm 2 and 80C, whereas exposure to 2 ppm C10H8 resulted in a drastic decrease in cell voltage to 0.1 V under the same conditions.…”

Spatial imaging of catalyst poisoning with SO2 on Pt/C PEFC electrocatalyst by operando Pt LIII-edge XAFS-CT imaging

“…2–6 The strong adsorption of S-containing compounds on Pt electrocatalysts often causes a rapid and drastic power loss of PEFC membrane electrode assembly (MEA). 7–9…”

“…[2][3][4][5][6] The strong adsorption of S-containing compounds on Pt electrocatalysts often causes a rapid and drastic power loss of PEFC membrane electrode assembly (MEA). [7][8][9] The poisoning of electrocatalysts with SO 2 has been investigated by applying electrochemical and spectroscopic techniques. Even at a trace concentration of less than 1 ppm SO 2 , the total power loss of PEFC leached over 30% after 20 h of SO 2 exposure.…”