Controlling cracking formation in fuel cell catalyst layers

Kumano, Naomi; Kudo, Kenji; Suda, Akihiko; Akimoto, Yusuke; Ishii, Masahiko; Nakamura, Hiroshi

doi:10.1016/j.jpowsour.2019.02.058

Cited by 87 publications

(65 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…These results imply that polymer adsorption onto particle surfaces plays a role in delaying crack nucleation to thicker particulate films. This result was qualitatively consistent with that reported by Kumano et al, 12 who demonstrated that crack behavior was controlled by ionomer adsorption in Pt/carbon catalyst inks.…”

Section: Resultssupporting

confidence: 93%

“…The compressive stress relaxes as the coating bends or contact lines move to shrink the film along the solid surface. When the contact lines are pinned on a rigid substrate, the suspension resists the transverse deformation and promotes the development of in‐plane tensile stresses, which often lead to radial, 2 circular, 3 zigzag, 4 star‐shaped, 5 or stripe 6‐10 trajectories of cracks that can degrade the final quality of industrial coating applications, such as fuel‐cell membrane electrode assemblies, 11,12 flexible conductive films, 13 paints, and cosmetics. Experimental studies on in situ stress measurements 14‐21 and theoretical investigations on the contact and deformation of packing elastic particles 8,22‐25 are being conducted to address this issue.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Adsorption‐mediated nonlinearity of critical cracking thickness in drying nanoparticle–polymer suspensions

Yamamura

2021

AIChE Journal

View full text Add to dashboard Cite

We examine the critical cracking thicknesses of as‐dried colloidal TiO2 suspensions containing water‐soluble polymeric additives, above which cracks spontaneously propagate. In contrast to common observations, the critical cracking thickness increases in a nonlinear, stepwise manner as increasing the concentration of the polymeric additive in the suspension. The critical thickness diverges when the polymer content increases above a certain threshold. We demonstrate that the first and second critical cracking thickness increments are attributable to the onset of polymer adsorption and a subsequent transition in the conformations of the adsorbing polymer chains, respectively. The critical thickness profiles with respect to normalized polymer adsorption amounts at different particle diameters converged into a single master curve. These results illustrate nontrivial evaporation processes in which the various roles of polymeric additives delay cracking into thicker films.

show abstract

Section: Resultssupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Adsorption‐mediated nonlinearity of critical cracking thickness in drying nanoparticle–polymer suspensions

Yamamura

2021

AIChE Journal

View full text Add to dashboard Cite

show abstract

“…Therefore, we consider that because platinum twines most ionomers and precipitated, the CL separated into a layer of only platinum and the mixing layer of platinum and ionomer during the catalyst ink drying process. Here, some researchers reported that ionomers indicate strong agglutination with Pt/CB in water-rich solution by hydrophobic interaction [ 25 , 26 ]. Kumano et al reported that although 23 wt.% of ionomers was adsorbed on the Pt/CB surface in the case of ink components shown on Table 3 , the ionomer of 77% was dispersed to the entire CL [ 25 ].…”

Section: Resultsmentioning

confidence: 99%

“…Here, some researchers reported that ionomers indicate strong agglutination with Pt/CB in water-rich solution by hydrophobic interaction [ 25 , 26 ]. Kumano et al reported that although 23 wt.% of ionomers was adsorbed on the Pt/CB surface in the case of ink components shown on Table 3 , the ionomer of 77% was dispersed to the entire CL [ 25 ]. Although we considered that the same phenomenon occurred in this study because the water and organic solvent ratio on our catalyst ink is approximate to the reference as shown on Table 3 , the ionomer hardly existed on the membrane side as shown in Figure 6 .…”

Section: Resultsmentioning

confidence: 99%

Influence of the Catalyst Layer Structure Formed by Inkjet Coating Printer on PEFC Performance

Tamaki

Sugiura

2021

Polymers

View full text Add to dashboard Cite

In this study, we investigated the influence of the Catalyst-Layer (CL) structure on Polymer Electrolyte Fuel Cell (PEFC) performance using an inkjet coating printer, and we especially focused on the CL thickness and the electrode area. In order to evaluate the influence of CL thickness, we prepared four Membrane Electrode Assemblies (MEAs), which have one, four, five and six CLs, respectively, and evaluated it by an overpotential analysis. As a result, the overpotentials of an activation and a diffusion increased with the increase of thickness of CL. From Energy Dispersive X-ray spectroscopy (EDX) analysis, because platinum twines most ionomers and precipitates, the CL separates into a layer of platinum with a big grain aggregate ionomer and the mixing layer of platinum and ionomer during the catalyst ink drying process. Consequently, the activation overpotential increased because the three-phase interface was not able to be formed sufficiently. The gas diffusivity of the multilayer catalyst electrode was worse than that of a single layer MEA. The influence of the electrode area was examined by two MEAs with 1 and 9 cm2 of electrode area. As a result, the diffusion overpotential of 9 cm2 MEA was worse than 1 cm2 MEA. The generated condensate was multiplied and moved to the downstream side, and thereafter it caused the flooding/plugging phenomena.

show abstract

“…Currently, measurements of particle size distribution 8–10 and rheological properties 1,11–14 as well as sedimentation tests 13–15 are used to evaluate the particle dispersion state in a slurry, and the optimization of the slurry condition is managed using these methods. However, by comparison with these slurry evaluation results, some unexpected results suggested that the slurry conditions whose particles appeared to be most dispersed differed depending on the evaluation method 16,17 .…”

Section: Introductionmentioning

confidence: 99%

Effect of medium condition change on green body density during casting and drying

Iwata

Yamada

Mori

2020

Int J Applied Ceramic Tech

View full text Add to dashboard Cite

The present study examined whether the optimum slurry conditions in which the green body with the highest packing fraction was fabricated were the same regardless of whether tape or slip casting methods were used. Additionally, we investigated the optimum slurry evaluation method to predict the packing fraction of each green body. Specifically, aqueous dense alumina slurries, whose particle dispersion state was changed by varying pH and the amount of dispersant additive, were prepared. After changing the pH, the optimum slurry conditions were achieved regardless of the casting method. The most suitable amount of additive dispersant differed due to the changing solution conditions during the casting and drying process; the medium of the slurry permeated into the plaster during slip casting and dried on the substrate during tape casting. Thus, in slip casting, non‐adsorbed polymers could also be permeated. Hence, it is crucial for slurry evaluation to predict the packing fraction of the slip cast body. A sedimentation test, which involved particle condensation as well as casting, was valid for the green sheet. Conversely, it was experimentally shown that the constant pressure filtration test, which involved the permeation of the medium in addition to particle condensation, was suitable for slip casting.

show abstract

Controlling cracking formation in fuel cell catalyst layers

Cited by 87 publications

References 30 publications

Adsorption‐mediated nonlinearity of critical cracking thickness in drying nanoparticle–polymer suspensions

Adsorption‐mediated nonlinearity of critical cracking thickness in drying nanoparticle–polymer suspensions

Influence of the Catalyst Layer Structure Formed by Inkjet Coating Printer on PEFC Performance

Effect of medium condition change on green body density during casting and drying

Contact Info

Product

Resources

About