Influence of trace oxygen in low-crossover proton exchange membrane fuel cells

Lead Research and Development Activity for DOE's High Temperature, Low Relative Humidity Membrane Program (Topic 2)

“…At issue with these "negative" crossovers is what is being reduced, the membrane or some other species? A study was carried out and published 18 that determined the source of the reduction reaction is trace oxygen. However, this was only present for membranes with extremely low hydrogen crossover values.…”

Voltammetric and galvanostatic methods for measuring hydrogen crossover in fuel cell

“…In this manner, all the hydrogen permeating through PEM is converted into a limiting hydrogen oxidation current (i.e., hydrogen crossover current), which is equivalent to the hydrogen crossover rate, and the key to the measurement is to isolate this component from the total current. Linear sweep voltammetry (LSV) is the most commonly used potential sweep technique in measuring hydrogen crossover (Brooker et al, 2012;Giner-Sanz et al, 2014;Huang et al, 2013;Hwang et al, 2018;Kocha et al, 2006;Niroumand et al, 2015;Wasterlain et al, 2011), but different scan rates always give rise to inconsistent results. Another electroanalytical method as a derivative of LSV is staircase voltammetry (also called as potential step method [PSM]), in which the potential sweep is a series of stair steps, and it has been employed in electrochemical measurements of hydrogen crossover (Schoemaker et al, 2014).…”

On‐line characterization of PEM 's oxygen permeability for PEM fuel cell by embedded microelectrode method

“…For conventional Pt‐free PEM, there are several ex situ methods for testing oxygen permeation, such as volumetric methods, 6 time‐delay methods, 7 gas chromatography tests, 8 and electrochemical method 9 . Electrochemical methods allow the monitoring of time‐dependent currents to obtain diffusion‐limiting conditions across the membrane and are now widely utilized to characterize the gas permeability of PEM 10,11 . In this method, a half‐cell electrochemical system is employed: one side of the membrane is in an acidic solution; the working electrode is placed on the surface of the membrane, while the counter electrode is placed in the solution; the reaction gas is supplied to the other side of the membrane; and the currents on both sides of the membrane are measured over time to estimate the diffusion coefficient and the solubility coefficient of the reactants in the membrane.…”

“…9 Electrochemical methods allow the monitoring of time-dependent currents to obtain diffusionlimiting conditions across the membrane and are now widely utilized to characterize the gas permeability of PEM. 10,11 In this method, a half-cell electrochemical system is employed: one side of the membrane is in an acidic solution; the working electrode is placed on the Shangshu Wang and Liuli Zeng are co-first authors of the article.…”