In this paper, we investigate contamination mechanisms and quantify the effect of organic model compounds aniline, diethyleneglycol monoethyl ether acetate, diethyleneglycol monoethyl ether, 4-methyl benzensulfonamide, benzyl alcohol, and 2,6-diaminotoluene that have been observed to originate from degradation of balance of plant materials on PEMFCs. In situ voltage loss can be quantified by contamination sources such as Pt, the ionomer, and the membrane using isotherm curves that are prepared by ex situ studies considering contamination mechanisms: adsorption on Pt, ion-exchange/absorption in membranes or electrodes. Severe kinetic loss of Pt activity on oxygen reduction reaction was observed for aromatic compounds due to the greater coverage on Pt/C than aliphatic compounds. An ion-exchange reaction by amine-containing aromatic compounds results in significant conductivity losses of the membrane/ionomer, which is main contributor of the performance loss in this study. That is, controlling the voltage losses caused by the membrane/ionomer contamination is critical to ensure the stability of the system. Infusion of non-amine containing compounds into PEMFCs also increased performance loss by an absorption mechanism but reached at steady state with reversible recovery by switching into normal operations without contaminants.

In situ performance data were measured to assess the degree of contamination from leachates of five families of balance of plant (BOP) materials (i.e., 2-part adhesive, grease, thread lock/seal, silicone adhesive/seal and urethane adhesive/seal) broadly classified as assembly aids that may be used as adhesives and lubricants in polymer electrolyte membrane fuel cell (PEMFC) systems. Leachate solutions, derived from soaking the materials in deionized (DI) water at elevated temperature, were infused into the fuel cell to determine the effect of the leachates on fuel cell performance. During the contamination phase of the experiments, leachate solution was introduced through a nebulizer into the cathode feed stream of a 50 cm 2 PEMFC operating at 0.2 A/cm 2 at 80 • C and 32%RH. Voltage loss and high frequency resistance (HFR) were measured as a function of time and electrochemical surface area (ECA) before and after contamination were compared. Two procedures of recovery, one self-induced recovery with DI water and one driven recovery through cyclic voltammetry (CV) were investigated. Performance results measured before and after contamination and after CV recovery are compared and discussed. While the energy conversion efficiency of proton exchange membrane fuel cell (PEMFC) systems is relatively high, economical applications have been limited due to initial stack costs and the degradation of performance over time which can be affected by contaminants that enter the system with the air or fuel feed stream, or component materials of construction leaching into the gas/water stream.1-12 Present-day requirements for durability limit the performance loss to 80 mV over required lifetimes of 5000 hours. Since potential cycling, start/stop, and idling conditions contribute to these performance losses, 11,[13][14][15] the tolerance for losses due to contamination is much smaller than 80 mV. In addition, with the recent reduction in cost related to the fuel cell stack, the relative cost of balance of plant has risen. This presents the opportunity to further reduce overall system cost by choosing functional, low cost BOP materials for PEMFC systems. Educated selection of BOP materials requires a level of understanding of potential contaminants from system components that does not currently exist in the literature. Chemically inert and low cost materials with low amounts of total and non-reactive leachates would be the most desirable materials for fuel cell applications.16 This paper focuses on the effect of leachates from system components on fuel cell performance and seeks to add to the limited knowledge base discussing PEMFC contaminants from system components. 2,3,5,[7][8][9]12,[17][18][19][20][21][22][23][24] Here we describe (1) a protocol to create leachate solutions from BOP materials, (2) ex situ quantification and speciation of the components present in the BOP leachate solutions, (3) in situ quantification of performance effect due to the leachate solutions and, (4) an attempt to correlate ex situ with in situ resu...

The ability to compare, analyze, and interpret laboratory-scale experimental data for polymer electrolyte membrane fuel cells (PEMFCs) is often limited by differences in the performance between 25 cm2 and 50 cm2 active area cells. The present study includes the material of gas diffusion layers (GDL), their compression pressure, and the operating conditions to quantify and understand the effect of these factors on the performance of PEMFCs with different active area of electrodes. The experimental data show that under the same compression the internal compression pressure is higher for smaller cells compared to larger cells. Typically one assumes by increasing the compression pressure that the contact resistance is decreased and better performance is obtained. However, further increase of compression may cause mass transfer resistance inside of GDL due to the change of physical properties including pore size distribution.