Microstructure and macroscopic rheology of microporous layer nanoinks for PEM fuel cells

Pan, Weitong; Chen, Zhekun; Yao, Dingsong; Chen, Xueli; Wang, Fuchen; Dai, Guohao

doi:10.1016/j.ces.2021.117001

Cited by 22 publications

(19 citation statements)

References 55 publications

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“…However, the presence of hydrophobic impurities improved the compatibility between the ionomer and solvent, thereby increasing the amount of free ionomer on the solvent. Consequently, this affected the interaction between the internal components and rheology of the catalyst ink [ 16 , 32 ]. Next, we investigated the effects of the atmosphere and temperature on the impurity generation process.…”

Section: Resultsmentioning

confidence: 99%

“…Coating and drying parameters influence the distribution of materials and pores in CLs and also have significant impacts on performance. Commonly, the ink formulation, including the alcohol content and type, ionomer content, and Pt dispersion, also affects the ink initial properties such as rheology, stability, and coatability, thereby exerting an influence on the fabrication of CLs [ 13 , 14 , 15 , 16 ]. However, the degradation of the catalyst ink quality after preparation also affects the catalyst ink viscosity, the size of agglomerates, which are a mixture of the catalyst and ionomer, the quality of the coated catalyst layer, and thus the performance of the fuel cells.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Degassing Treatment on the Ink Properties and Performance of Proton Exchange Membrane Fuel Cells

Liu

Yang

et al. 2022

Membranes

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Degradation occurs in catalyst inks because of the catalytic oxidation of the solvent. Identification of the generation process of impurities and their effects on the properties of HSC ink and LSC ink is crucial in mitigating them. In this study, gas chromatography-mass spectrometry (GC-MS) and cyclic voltammetry (CV) showed that oxidation of NPA and EA was the primary cause of impurities such as acetic acid, aldehyde, propionic acid, propanal, 1,1-dipropoxypropane, and propyl propionate. After the degassing treatment, the degradation of the HSC ink was suppressed, and the concentrations of acetic acid, propionic acid, and propyl propionate plummeted from 0.0898 wt.%, 0.00224 wt.%, and 0.00046 wt.% to 0.0025 wt.%, 0.0126 wt.%, and 0.0003 wt.%, respectively. The smaller particle size and higher zeta potential in the degassed HSC ink indicated the higher utilization of Pt, thus leading to optimized mass transfer in the catalyst layer (CL) during working conditions. The electrochemical performance test result shows that the MEA fabricated from the degassed HSC ink had a peak power density of 0.84 W cm−2, which was 0.21 W cm−2 higher than that fabricated from the normal HSC ink. However, the introduction of propionic acid in the LSC ink caused the Marangoni flux to inhibit the coffee ring effect and promote the uniform deposition of the catalyst. The RDE tests indicated that the electrode deposited from the LSC ink with propionic acid possessed a mass activity of 84.4 mA∙mgPt−1, which was higher than the 60.5 mA∙mgPt−1 of the electrode deposited from the normal LSC ink.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influence of Degassing Treatment on the Ink Properties and Performance of Proton Exchange Membrane Fuel Cells

Liu

Yang

et al. 2022

Membranes

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“…PTFE is usually dispersed in a stable aqueous suspension (5-45 wt.% concentration) which can be applied to the GDL with different techniques, namely: dipping or floating of the carbon support in the suspension [34,45], brushing, spraying [36], vacuum-drying [33,35,46]. Different techniques have been introduced in specific cases, and the effect of homogeneous or nonhomogeneous polymer distributions in the GDL has been studied [47,48]. However, dipping has become the standard procedure due to its simplicity and possible scalability at the industrial level.…”

Section: Ptfementioning

confidence: 99%

The Role of Fluorinated Polymers in the Water Management of Proton Exchange Membrane Fuel Cells: A Review

et al. 2021

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As the hydrogen market is projected to grow in the next decades, the development of more efficient and better-performing polymer electrolyte membrane fuel cells (PEMFCs) is certainly needed. Water management is one of the main issues faced by these devices and is strictly related to the employment of fluorinated materials in the gas diffusion medium (GDM). Fluorine-based polymers are added as hydrophobic agents for gas diffusion layers (GDL) or in the ink composition of microporous layers (MPL), with the goal of reducing the risk of membrane dehydration and cell flooding. In this review, the state of the art of fluorinated polymers for fuel cells is presented. The most common ones are polytetrafluoroethylene (PTFE) and fluorinated ethylene propylene (FEP), however, other compounds such as PFA, PVDF, PFPE, and CF4 have been studied and reported. The effects of these materials on device performances are analyzed and described. Particular attention is dedicated to the influence of polymer content on the variation of the fuel cell component properties, namely conductivity, durability, hydrophobicity, and porosity, and on the PEMFC behavior at different current densities and under multiple operating conditions.

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“…It should be noted that the continuous R2R slot die coating technique has recently shown great potential for polymer electrolyte membrane (PEM) fuel cells 3,6–8 . The membrane electrode assembly (MEA), the core component within the PEM fuel cells, is a multilayer thin‐film stack composed of a PEM, catalyst layers (CLs), and gas diffusion layers (GDLs) 9 . It is expected that the cost‐effective R2R slot die coating technique could address the challenges of precise and mass production faced by PEM fuel cells toward their commercialization 8–11 …”

Section: Introductionmentioning

confidence: 99%

“…9,34 In the coatings of particle suspensions, the performance of the coated product depends not only on the macroscopic uniform film structure but also on the inner microstructure of the coated layer. In our previous study, 9 it was experimentally found that poorlydispersed ink with large agglomerates yields a heterogeneous porous structure with phase-separated cracks. The defective crack structure would deteriorate the cell performance and durability.…”

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confidence: 99%

Slot die coating window for a uniform fuel cell ink dispersion

Pan

Chen

et al. 2022

AIChE Journal

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The continuous roll‐to‐roll slot die coating technique has shown great potential for fuel cell electrode fabrication. It is essential to determine the particulate coating window to obtain a defect‐free film of uniform thickness and uniform particle dispersion. For this dual‐purpose, an additional upper operating limit has been proposed via a “flow field analysis scheme” that combines analysis and simulation. In this analysis, the fundamentals of flow pattern transition (Poiseuille–Couette–bubbly flow) behind coating limits are clarified. The Couette flow is advantageous for uniform shear rate and dispersion. Furthermore, phase‐field simulations systematically investigate the effect of fluid and geometrical parameters and quantitatively present the flow limit with explicit expression. Results reveal that the slope of the upper limit is inversely correlated with shear‐thinning index n while proportional to the coating gap H. Combining the bubble entrainment boundary, lower n and H are favorable for a larger particulate coating window.

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Microstructure and macroscopic rheology of microporous layer nanoinks for PEM fuel cells

Cited by 22 publications

References 55 publications

Influence of Degassing Treatment on the Ink Properties and Performance of Proton Exchange Membrane Fuel Cells

Influence of Degassing Treatment on the Ink Properties and Performance of Proton Exchange Membrane Fuel Cells

The Role of Fluorinated Polymers in the Water Management of Proton Exchange Membrane Fuel Cells: A Review

Slot die coating window for a uniform fuel cell ink dispersion

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