Performance Recovery of Fuel Cell Stack for FCEV

A Comparative Study of Conditioning Methods for Hydrocarbon‐Based Proton‐Exchange Membrane Fuel Cells for Improved Performance

“…This study evaluated and developed VR procedures for fully hydrocarbon-based PEM fuel cells with the aim of improving their activity and performance. Specifically, a novel VR procedure based on voltage steps was compared to those proposed by the US DOE and Kabir et al [1] The performance of the fuel cells decreased when subjected to the DOE VR, while the mass activity was improved by 70% when exposed to the VR from Kabir et al [1] for 3 h. This improvement is likely due to the desorption and removal of sulfate and sulfonate group contaminants from the active catalyst sites, which is assisted by a voltage hold at 0.1 V. [1,6] The results of this study show that our optimized VR improved the mass activity of the PEM fuel cells by 100% in only 1 h, which is one-third of the time used for the VR from Kabir et al [1] Moreover, the optimized VR also improved the mass activity of the reference cells with Nafion cathode catalyst layer by 80%. Given that the conditioning time of fuel cell stacks is a critical bottleneck, these findings suggest that better VR protocols could be developed for hydrocarbon membranes and ionomers, which have different properties compared to PFSAs.…”

“…The term "recovery" used in this work refers explicitly to the in situ electrochemical conditioning of the fuel cell electrode to remove possible surface oxides (Pt-O) and impurities (e.g., sulfonate anions or solvents from the fabrication process). [2] There are several approaches for VR used on perfluorinated sulfonic acid (PFSA)based fuel cells, including 1) high current density operation under elevated temperatures and high back pressure, [4] 2) low potential (<0.2 V) at low temperature and oversaturated conditions, [1,[5][6][7] 3) current/voltage/reactant cycling/pulses, [8,9] 4) air braking/cathode starvation, [10] and 5) hydrogen pumping, [11] and combinations of these methods. [12,13] To achieve optimal fuel cell performance, selecting an appropriate recovery procedure is crucial.…”

“…The potential explanations range from surface oxide or contaminant removal to the restructuring of the membrane and electrode ionomer. [1,5] Low cell voltages are believed to facilitate the desorption of sulfonate anions (SO 3 À ) from catalyst sites, [6,14] which can impede the oxygen reduction reaction (ORR) and lead to lower kinetic activity and performance. [4] Oversaturated conditions, combined with higher water production rates at low potentials under H 2 /air, can lead to "flooding" of the catalyst layer, which can help reduce the adsorption of sulfonate groups on the catalyst surface.…”

“…In addition to maximizing the performance, it is essential to reduce the conditioning duration to ramp up fuel cell production. [2] For more information on various VR conditions and their corresponding mechanisms, readers are directed to excellent review articles by Kocha and Pollet, [2] Christmann et al, [3] Choo et al, [6] and Mitzel et al [4]…”

A review on the Proton-Exchange Membrane Fuel Cell break-in physical principles, activation procedures, and characterization methods

“…Pre-heating and humidifying the gas may accelerate the desorption process, and hydrate the ionomer to a certain extend. Another strategy to expose the cathode to a reducing atmosphere consists of purging it of air and imposing a vacuum, whilst supplying the anode with hydrogen [78]. The cathode fills with hydrogen, as the pressure difference forces H2 crossover through the membrane (which may also affect CL porosity).…”