Characterization of gas crossover and its implications in PEM fuel cells

Effects of open-circuit operation on membrane and catalyst layer degradation in proton exchange membrane fuel cells

“…These increases indicate a high gas crossover rate and a high internal electronic short circuit between the two electrodes. Although the Nafion electrolyte is designed to be an ionic conductor but not an electronic conductor, finite electrical shorts between anode and cathode may occur as a result of electrolyte thinning or pinhole formation [10,17]. Therefore, it can be concluded that severe membrane structural damage occurred during 206-256 h of OC operation, which is responsible for the OCV decrease, and the second recovery process could not mitigate this membrane degradation, as shown by the sustained higher crossover current density in Fig.…”

“…The research reveals that the membrane properties (such as composition and thickness) and the environment (such as pressure, temperature, and humidification) are the determining factors in the crossover rate. Hydrogen crossover rates are in the order of a few milliamps to tens of milliamps per square centimetre, while oxygen permeates at about half that rate [10].…”

“…However, gas crossover through the thin Nafion membrane is inevitable during PEM fuel cell operation, especially when no reactant is consumed under OC conditions. Several researchers have investigated the permeation of hydrogen and oxygen in order to clarify the gas crossover rate through Nafion membranes in PEM fuel cells [9,10]. The research reveals that the membrane properties (such as composition and thickness) and the environment (such as pressure, temperature, and humidification) are the determining factors in the crossover rate.…”

Investigations on degradation of the long-term proton exchange membrane water electrolysis stack

“…7 shows the hydrogen crossover rate of the membrane before and after 7800 h operation. The hydrogen crossover rate can be determined using the plateau current density at voltage above 0.35 V, where the current density obtained is limited by the hydrogen transport rate through the membrane [27]. As shown in Fig.…”

Modeling Water Management in Polymer-Electrolyte Fuel Cells

“…43 In addition, recent studies have also shown that the dilution effect by crossover of nitrogen can be important. 79 For the above reasons, membrane modeling should account for gas crossover. The easiest method to do this is to use experimentally measured permeation coefficients (which increase with water content and temperature)…”