Proton exchange membranes for polymer electrolyte fuel cells: An analysis of perfluorosulfonic acid and aromatic hydrocarbon ionomers

García-Salaberri, Pablo A.

doi:10.1016/j.susmat.2023.e00727

Cited by 6 publications

(5 citation statements)

References 358 publications

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“…This range agrees with previous experimental data reported for the oxygen diffusivity in bulk Nafion membranes, even though there is a large variability among authors (three orders of magnitude) [35]. The large fluctuation of the diffusivity in bulk Nafion can be ascribed to conditioning, substrate interaction, and confinement of membranes [46][47][48]. The oxygen diffusivity considered here is a good approximation, which leads to realistic values of the local oxygen transport resistance.…”

Section: Calibrationsupporting

confidence: 90%

A Numerical Assessment of Mitigation Strategies to Reduce Local Oxygen and Proton Transport Resistances in Polymer Electrolyte Fuel Cells

García-Salaberri

2023

Materials

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The optimized design of the catalyst layer (CL) plays a vital role in improving the performance of polymer electrolyte membrane fuel cells (PEMFCs). The need to improve transport and catalyst activity is especially important at low Pt loading, where local oxygen and ionic transport resistances decrease the performance due to an inevitable reduction in active catalyst sites. In this work, local oxygen and ionic transport are analyzed using direct numerical simulation on virtually reconstructed microstructures. Four morphologies are examined: (i) heterogeneous, (ii) uniform, (iii) uniform vertically-aligned, and (iv) meso-porous ionomer distributions. The results show that the local oxygen transport resistance can be significantly reduced, while maintaining good ionic conductivity, through the design of high porosity CLs (ε≃ 0.6–0.7) with low agglomerated ionomer morphologies. Ionomer coalescence into thick films can be effectively mitigated by increasing the uniformity of thin films and reducing the tortuosity of ionomer distribution (e.g., good ionomer interconnection in supports with a vertical arrangement). The local oxygen resistance can be further decreased by the use of blended ionomers with enhanced oxygen permeability and meso-porous ionomers with oxygen transport routes in both water and ionomer. In summary, achieving high performance at low Pt loading in next-generation CLs must be accomplished through a combination of high porosity, uniform and low tortuosity ionomer distribution, and oxygen transport through activated water.

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Section: Calibrationsupporting

confidence: 90%

A Numerical Assessment of Mitigation Strategies to Reduce Local Oxygen and Proton Transport Resistances in Polymer Electrolyte Fuel Cells

García-Salaberri

2023

Materials

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“…As illustrated in Figure 6A, the higher uniformity of ionomer films prevented agglomeration and the formation of deactivated ionomer-free regions. Consequently, an optimal balance was achieved between ionic and mass transport losses, increasing performance at low Pt loading (see polarization curves with Vulcan in Figure 6B) (García-FIGURE 5 (A) Oxygen permeability, P O2 , reported for Nafion and modified ionomers with an enhanced oxygen transport structure (Macauley et al, 2022;García-Salaberri, 2023a). (B) Polarization curves, I − V, reported using conventional and porous ionomers (Cheng et al, 2022b;Zhang et al, 2022).…”

Section: Effect Of Ionomer Distribution On Catalyst Particlesmentioning

confidence: 99%

“…A decrease of EW leads to an increase in the number of protogenic groups in ionomer, so that water uptake and ionic conductivity are typically promoted (Kusoglu and Weber, 2017;García-Salaberri, 2023a). The higher water volume fraction and shorter side chains in ionomer facilitates oxygen transport through ionomer, leading to a decrease of R local O2 .…”

Section: Effect Of Ionomer Content and Morphologymentioning

confidence: 99%

Local oxygen transport resistance in polymer electrolyte fuel cells: origin, dependencies and mitigation

García-Salaberri,

Das,

Chaparro

2024

Front. Energy Res.

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Next-generation polymer electrolyte fuel cells (PEFCs) require an integral design of the porous structure of electrodes at different scales to improve performance and enlarge durability while reducing cost. One of today’s biggest challenges is the stable, high-performance operation at low Pt loading due to the detrimental effect of the local oxygen transport resistance caused by ionomer around catalyst sites. Hindered local oxygen transport arises from sluggish kinetics at the local reaction environment, that comprises adsorption at (wet) ionomer and Pt interfaces, and diffusivity of gas species in ionomer and water. Diverse factors affect oxygen transport, including operating conditions (relative humidity, temperature, and pressure), ionomer content and morphology, ionomer heterogeneity, porosity of carbon support, catalyst dispersity, and flooding. To attain performance and durability targets, it is essential to maximize the oxygen utilization of the catalyst layer by implementing enhanced membrane electrode assembly architectures. This involves employing advanced catalyst layer preparation techniques, including electrospraying, to generate optimized highly porous morphologies. Furthermore, achieving these targets necessitates the development of new materials with tailored properties, such as high permeability and porous ionomers, among other innovative strategies.

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“…Acid−base polymer membranes incorporated with fillers are promising candidates as PEMs because of their exceptional proton conductivity and durability at high operating temperatures. 7,8 Various composite membranes have been fabricated with different polymer matrixes, like poly(benzimidazole) (PBI), poly(vinylidene fluoride), 9 poly(ether ether ketone), 10 poly(styrene−ethylene−butylene− styrene), 11 poly(vinyl alcohol), 12 polyimide, 13 etc.…”

Section: Introductionmentioning

confidence: 99%

“…However, it still cannot meet all of the parameters needed for PEMFC due to its high cost, difficulty in the synthesis procedure, limited proton conductivity, and stability under high operating temperatures. , Developing PEMs with electrochemical durability, chemical and thermal stability, and high proton conductivity is a significant area of research. Acid–base polymer membranes incorporated with fillers are promising candidates as PEMs because of their exceptional proton conductivity and durability at high operating temperatures. , Various composite membranes have been fabricated with different polymer matrixes, like poly(benzimidazole) (PBI), poly(vinylidene fluoride), poly(ether ether ketone), poly(styrene–ethylene–butylene–styrene), poly(vinyl alcohol), polyimide, etc.…”

Section: Introductionmentioning

confidence: 99%

Sulfonated Cobalt Metal–Organic Framework Embedded Mixed Matrix Membrane towards Fuel-Cell Applications

Moorthy,

Deivanayagam

2024

ACS Appl. Mater. Interfaces

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New strategies for enhancement of the fuel-cell performance of a poly(2,5-benzimidazole) (ABPBI) membrane loaded with a functionalized cobalt-based metal−organic framework (MOF) for H 2 −O 2 fuel cells. ABPBI was prepared using the polycondensation method, and various proportions of sulfonated cobalt MOF (sCo-MOF) were incorporated into ABPBI to fabricate a proton-exchange membrane (PEM). Later, the fabricated membranes were soaked in 1 M sulfuric acid to produce sulfonated PEMs. The developed composite membranes had increased proton conductivity, tensile strength, physicochemical properties, and fuelcell performance compared to the sulfonated ABPBI (sABPBI) membrane. A membrane embedded with 4 wt % sCo-MOF shows higher water uptake and ion-exchange capacity values of 23.25% and 2.89 mequiv g −1 , respectively. The membrane electrode assemblies were fabricated to perform unit-cell tests for both sABPBI and 4 wt % sCo-MOF/sABPBI membranes. The 4 wt % sCo-MOF-loaded sABPBI membrane demonstrated good unit-cell performance in the fuelcell test, with a power density of 415.8 mW cm −2 at 80 °C, superior to the pristine sABPBI membrane's power density of 178.6 mW cm −2 .

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Proton exchange membranes for polymer electrolyte fuel cells: An analysis of perfluorosulfonic acid and aromatic hydrocarbon ionomers

Cited by 6 publications

References 358 publications

A Numerical Assessment of Mitigation Strategies to Reduce Local Oxygen and Proton Transport Resistances in Polymer Electrolyte Fuel Cells

A Numerical Assessment of Mitigation Strategies to Reduce Local Oxygen and Proton Transport Resistances in Polymer Electrolyte Fuel Cells

Local oxygen transport resistance in polymer electrolyte fuel cells: origin, dependencies and mitigation

Sulfonated Cobalt Metal–Organic Framework Embedded Mixed Matrix Membrane towards Fuel-Cell Applications

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