There are significant impacts to fuel cell performance when contaminant cations replace protons in the ionomer. The purpose of this paper is directly correlate extent cationic contamination with and also elucidate main mechanisms responsible for degradation. A series standard membrane electrode assemblies (MEAs) were contaminated by varying ratio cesium ionomer phase. amount was determined using X-ray Fluorescence (XRF) Spectroscopy. These MEAs then run mode determine as a function level....

Collagen-chondroitin sulfate biomaterial scaffolds have been used in a number of tissue-engineered products under development or the clinics. In this article, we describe new approach based on centrifugation for obtaining highly concentrated yet porous collagen scaffolds. Water uptake, chondroitin retention, morphology, mechanical properties, and tissue-engineering potential were investigated. Our results show that can lead to containing four times as much conventional unconcentrated...

Accurate characterization of polymer-electrolyte fuel cells (PEFCs) requires understanding the impact mechanical and electrochemical loads on cell components. An essential aspect this relationship is effect compression polymer membrane's water-uptake behavior transport properties. However, there limited information physical constraints membrane In paper, we investigate both theoretically experimentally how water uptake Nafion changes under external loads. The swelling a compressed modeled by...

Over the last 20 years great progress has been made in increasing fuel cell performance and durability while reducing overall system cost, so much that commercialization of cells for automotive stationary applications is nearing economic feasibility. Still, further advances are needed before potential polymer electrolyte membrane (PEMFC) can be realized. The incorporation advanced thin reinforced ionomer membranes into electrode assembly (MEA) paramount to PEMFC progress1. Further reductions...

When cationic impurities, such as Na+, Ca2+, ammonium or metal cations, are present in a polymer electrolyte membrane fuel cell (PEMFC) the performance of PEMFC can be significantly reduced. A half model was developed to explain most relevant processes causing degradation cells under contamination. In contaminated with foreign cations exchange current density and limiting decreases. These effects explained by accounting for concentration available protons CCL transport diffusion migration.

Electrochemical experimentation and modeling indicates that impurities degrade fuel cell performance by a variety of mechanisms. Electrokinetics may be inhibited catalytic site poisoning from sulfur compounds CO decreased local proton activity mobility caused the presence foreign salt cations or ammonia. Cation impurity profiles vary with current density, valence change conductivity water concentrations in ionomer. Nitrogen oxides ammonia species electrochemically active under operating...

X-ray computed tomography was used to visualize the water configurations inside gas diffusion layers for various applied capillary pressures, corresponding both invasion and withdrawal. A specialized sample holder developed allow pressure control on small-scale samples required. Tests were performed GDL specimens with without hydrophobic treatments.

An adaptable technique for micropatterning biomaterial scaffolds has enormous implications in controlling cell function and the development of tissue-engineered (TE) microvasculature. In this paper, we report a to embed microscale patterns onto collagen-glycosaminoglycan (CG) membrane as first step toward creation TE constructs with built-in The CG membranes were fabricated by homogenizing solution type-I bovine collagen chondroitin-6-sulfate acetic acid vacuum filtering subsequently....

Cationic contamination of polymer electrolyte fuel cells has been shown to cause serious performance degradation but the exact mechanisms this are not fully understood. A strip cell configuration was devised study due cationic by changing time and length scales traditional while providing a suitable reference electrode. This "strip cell" utilizes Nafion® membranes in an in-plane with electrodes painted on each end. Using it determined that contaminants collect near cathode under load profile...

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Megawatt scale energy storage that is reliable, safe, and cost effective necessary for the integration of highly intermittent renewable sources advanced grid technologies into our current electricity grid. These systems also need to show high round trip efficiency, power, sufficient capacity, versatile modes operation maximize their value. Zinc/iron (Zn/Fe) hybrid flow batteries have promise meet these demands due inexpensive, relatively abundant electrolyte chemistries. This presentation...

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