Editors’ Choice—Examining Performance and Durability of Anion Exchange Membrane Fuel Cells with Novel Spirocyclic Anion Exchange Membranes

Abstract

A series of spirocyclic copolymer membranes with varying ion exchange capacities (IECs) were investigated to probe the impact of polymer properties on in situ fuel cell performance and stability. In-situ electrochemical tests and post-mortem electron microscopy analysis of cross-sectioned membrane electrode assemblies (MEAs) have been combined with voltage loss breakdown analysis to evaluate the performance and degradation of different MEAs, and to probe the catalyst morphology and electrode structure at different stages of operation. Voltage loss breakdown results show that membrane degradation and kinetic losses played only a minor role in observed performance degradation and that performance losses were primarily related to increasing mass transport losses. From microscopy studies, carbon corrosion and Pt nanoparticle growth were identified at both the cathode and anode although more pronounced on the cathode resulting in significant structural changes. The membrane with the lowest IEC (1.3 mmolg −1 ) demonstrated the lowest peak power density~1.16 W cm −2 , however, it showed the most stable performance (constant 0.6 A cm −2 hold) with~5% degradation over 540 h. Isolation of performance losses and microscopic analysis of electrodes for anion exchange membrane fuel cells has not been reported previously, and these results help identify critical performance degradation concerns.

Oxygen Reduction Reaction Kinetics on a Pt Thin Layer Electrode in Aemfc

“…Our CO results differ from those reported by Yang-Neyerlin et al [45], where the CO profiles from porous Pt, sandwiched with spirocyclic membranes and PtRu as counter electrode, exhibited a highly pronounced pre-wave. By using partial CO stripping experiments in solutions at different pH, Farias et al [46] reported that the oxidation of a CO adlayer containing a significant number of defects gives rise to the presence of highly distinguishable pre-waves in the stripping voltammograms.…”

“…3 manifests a CO electrooxidation that, initiated on a disordered point, ignited via a nucleation-growth mechanism [49]. Another important aspect of Yang-Neyerlin's results [45] is that the CO electrooxidation onto porous Pt only succeed when the MEAs had a low H 2 crossover. This points out the importance to minimize this effect when performing CO stripping.…”

“…The partial pressures are corrected with respect to the RH. Due to H 2 crossover, a mixed potential is obtained at the electrode [45,56]. As the O 2 partial pressure is decreased, the effect is more pronounced, giving an overall decrease of around 100 mV when lowering the p O2 from 100% to 10%, and roughly half of that decrease occurs between 20% and 10%.…”

CeO2 Modulates the Electronic States of a Palladium Onion-Like Carbon Interface into a Highly Active and Durable Electrocatalyst for Hydrogen Oxidation in Anion-Exchange-Membrane Fuel Cells

“…These anodes may also suffer from anode flooding at high humidification and such a phenomenon could be a cause of the performance loss. State-of-the-art commercial PtRu/C anode catalysts perform best at higher RHs (90–100%) . For example, a 2000 h stability test of a PtRu/C MEA was undertaken at 90% RH and showed only a 3.65% performance loss .…”

Quaternized Polynorbornene Random Copolymers for Fuel Cell Devices

“…The peak power density achieved with QPN was 1.07 W/cm 2 , comparable to other high performing AEMFC membranes of similar thickness. 61,62 Compared to other polyolefinic membranes, the VAPNB-based materials can be processed as mechanically stable thin membranes because of their high thermal and mechanical stability. In addition, the hydrophobic aliphatic backbone structure combined with a thin membrane makes the VAPNB-based AEM able to transport water quickly to the cathode side, which makes the HFR stable at high current density, i.e., > 1 A cm −2 .…”