Effect of rheological properties of catalyst slurry on the structure of catalyst layer in PEMFC

Yang, Daozeng; Guo, Yuqing; Tang, Haifeng; Yang, Daijun; Ming, Pingwen; Zhang, Cunman; Li, Bing; Zhu, Shengli

doi:10.1016/j.ijhydene.2021.12.227

Cited by 15 publications

(7 citation statements)

References 39 publications

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“…The process of constructing CLs and even the precursor dispersions can vary significantly among different researchers. 35 We focus on the preparation process utilized by Berlinger et al 23 Nafion-D2021 (EW = 1000 g/equiv) dispersion stock solutions (Ion Power Inc., New Castle, DE) were diluted to the desired concentration by water/n-propanol solutions of choice and sonicated for 1 h to breakup preformed aggregates. This process allows for uniformity in initial conditions given that stock solutions may change over long time periods and thus are aggregated to different extents.…”

Section: Dispersion Preparationmentioning

confidence: 99%

Colloidal Stability of PFSA-Ionomer Dispersions Part II: Determination of Suspension pH Using Single-Ion Potential Energies

Srivastav,

Weber,

Radke

2024

Langmuir

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Perfluorosulfonic acid (PFSA) ionomers serve a vital role in the performance and stability of fuel-cell catalyst layers. These properties, in turn, depend on the colloidal processing of precursor inks. To understand the colloidal structure of fuel-cell catalyst layers, we explore the aggregation of PFSA ionomers dissolved in water/alcohol solutions and relate the predicted aggregation to experimental measurements of solution pH. Not all side chains contribute to measured pH because of burying inside particle aggregates. To account for the measured degree of dissociation, a new description is developed for how PFSA aggregates interact with each other. The developed single-counterion electrostatic repulsive pair potential from Part I is incorporated into the Smoluchowski collision-based kinetics of interacting aggregates with buried side chains. We demonstrate that the surrounding solvent mixture affects the degree of aggregation as well as the pH of the system primarily through the solution dielectric permittivity, which drives the strength of the interparticle repulsive energies. Successful pH prediction of Nafion ionomer dispersions in water/n-propanol solutions validates the numerical calculations. Nafion-dispersion pH measurements serve as a surrogate for Nafion particle-size distributions. The model and framework can be leveraged to explore different ink formulations.

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Section: Dispersion Preparationmentioning

confidence: 99%

Colloidal Stability of PFSA-Ionomer Dispersions Part II: Determination of Suspension pH Using Single-Ion Potential Energies

Srivastav,

Weber,

Radke

2024

Langmuir

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“…With the increase in standing time of the slurry, the network structure of the slurry was strengthened; thus, the CL made by the static slurry had fewer cracks, while the surface of the CL became more uneven. On the one hand, this might be due to the agglomeration of clusters inside the slurry, which led to the formation of larger particles, while on the other hand, the particles on the surface of CL were much larger than those measured by DLS, indicating that the agglomeration behavior of clusters in the slurry was intensified in the process of solvent evaporation …”

Section: Resultsmentioning

confidence: 97%

“…On the one hand, this might be due to the agglomeration of clusters inside the slurry, which led to the formation of larger particles, while on the other hand, the particles on the surface of CL were much larger than those measured by DLS, indicating that the agglomeration behavior of clusters in the slurry was intensified in the process of solvent evaporation. 48 The hydrophilicity of CL can affect the internal water management of fuel cells. If the water generated by the reaction is not removed in time, it might affect the mass transfer of gas and reduce the performance of the fuel cell.…”

Section: Physical Characterization Resultsmentioning

confidence: 99%

“…47 In addition, a larger storage modulus G′ of the slurry usually indicates more obvious solid characteristics of the fluid, suggesting that the slurry might have a stronger network structure. 48 Figure 4d−f shows the amplitude scanning results of the slurry prepared under three kinds of probe ultrasonic intensity. The results showed that the storage modulus and viscosity of the slurry had the same variation law, which also showed that the viscosity of the slurry was mainly due to the change in its internal network structure strength.…”

Section: Physical Characterization Resultsmentioning

confidence: 99%

“…The viscoelasticity of the slurry is an important characterization of its fluid behavior . In addition, a larger storage modulus G′ of the slurry usually indicates more obvious solid characteristics of the fluid, suggesting that the slurry might have a stronger network structure Figure d–f shows the amplitude scanning results of the slurry prepared under three kinds of probe ultrasonic intensity.…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Effects of Electrostatic Force and Network Structure on the Stability of Proton-Exchange Membrane Fuel Cell Catalyst Ink

Xie

Guo

Yang

et al. 2023

ACS Appl. Mater. Interfaces

Self Cite

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The stability of the catalyst slurry of a protonexchange membrane fuel cell (PEMFC) is of great significance to its large-scale production and commercialization. In this study, three kinds of slurries with different stabilities were prepared using different probe ultrasonic powers. The influence of electrostatic force and network structure on slurry stability was also studied. In addition, the catalyst layer (CL) and membrane electrode assembly (MEA) were further tested to determine the relationship between slurry stability, CL, and MEA performance. The results showed that the slurry prepared with 600 W dispersion power had the least agglomeration on day 12, which is due to the clusters in the slurry having the smallest average particle size and the largest surface area, thereby allowing them to absorb the most Nafion and have the largest electrostatic force to inhibit agglomeration. However, the slurry with 1200 W dispersion power had the least sedimentation after 9.4 days because the strength of the network structure in the slurry strengthened the most, resulting in a significant increase in viscosity and inhibition of sedimentation. Electrochemical tests showed that the MEA gradually exhibited worse electrical performance and higher impedance due to the agglomeration of catalyst particles caused by the standing process. Altogether, this study provides insights to better understand and regulate the stability of catalyst slurries.

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Effect of Catalyst Ink Properties on the Performance of Proton Exchange Membrane Fuel Cell and Water Electrolyzer: A Mini Review

Choi,

Kang,

et al. 2024

Korean J. Chem. Eng.

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Effect of rheological properties of catalyst slurry on the structure of catalyst layer in PEMFC

Cited by 15 publications

References 39 publications

Colloidal Stability of PFSA-Ionomer Dispersions Part II: Determination of Suspension pH Using Single-Ion Potential Energies

Colloidal Stability of PFSA-Ionomer Dispersions Part II: Determination of Suspension pH Using Single-Ion Potential Energies

Effects of Electrostatic Force and Network Structure on the Stability of Proton-Exchange Membrane Fuel Cell Catalyst Ink

Effect of Catalyst Ink Properties on the Performance of Proton Exchange Membrane Fuel Cell and Water Electrolyzer: A Mini Review

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