New Preparation Method for Polymer‐Electrolyte Fuel Cells

Uchida, Makoto; Aoyama, Yuko; Eda, Nobuo; Ohta, Akira

doi:10.1149/1.2044068

Cited by 304 publications

(210 citation statements)

References 2 publications

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“…Nafion, and much has been reported on the structure-properties relationships of LSC-PFSA-based CLs [3]. During CL fabrication, carbon-supported Pt and ionomer segregates on various length scales into bicontinuous percolating phases, the optimal Nafion content being ∼30-35 wt% [4][5][6][7][8]. For automotive applications it is preferable that PEMFCs operate at temperatures >100 • C and low RH but LSC-PFSA ionomer loses proton conductivity above 90 • C and under lower RH [9].…”

Section: Introductionmentioning

confidence: 99%

Fuel cell catalyst layers containing short-side-chain perfluorosulfonic acid ionomers

Péron

Edwards

Haldane

et al. 2011

Journal of Power Sources

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Porous catalyst layers (CLs) containing short-side-chain (SSC) perfluorosulfonic acid (PFSA) ionomers of different ion exchange capacity (IEC: 1.3, 1.4 and 1.5 meq g −1 ) were deposited onto Nafion 211 to form catalyst-coated membranes. The porosity of SSC-PFSA-based CLs is larger than Nafion-CL analogues. CLs incorporating SSC ionomer extend the current density of fuel cell polarization curves at elevated temperature and lower relative humidity compared to those based on long-side chain PFSA (e.g., Nafion)-based CLs. Fuel cell polarization performance was greatly improved at 110• C and 30% relative humidity (RH) when SSC PFSI was incorporated into the catalyst layer.Crown

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Section: Introductionmentioning

confidence: 99%

Fuel cell catalyst layers containing short-side-chain perfluorosulfonic acid ionomers

Péron

Edwards

Haldane

et al. 2011

Journal of Power Sources

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“…These objectives can be accomplished via altering the constituent loading (solid content) in an ink or changing the solvent. [3][4][5][6][7][8][9][10] This approach is sound for non-active coatings such as paints and barrier coatings but has significant drawbacks for active coatings (i.e. electrodes).…”

mentioning

confidence: 99%

Catalyst Layer Ink Interactions That Affect Coatability

Dixit

Harkey

Shen

et al. 2018

J. Electrochem. Soc.

103

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Catalyst layer inks are examples of biphasic material systems composed of a solid material, a polymer, and a solvent. Nanoscale interactions between the individual constituents can alter macroscopic properties that are relevant for coating and manufacturing processes (i.e. viscosity, surface tension, aggregation, and rheology). Control over these macroscale properties are important for controlled electrode formation during scalable roll-to-roll manufacturing. The underlying interactions include polymer|particle, particle|solvent, and polymer|solvent interactions. In this work we systematically investigate polymer|particle interactions via studying a range of formulated inks composed of different solvents (methanol, isopropyl alcohol, octanol, and water), varying polymer loadings, and particles with different surface charges. Ink aging is also addressed and over short time periods (<1 hr shelf life) the addition of a perfluorosulfonic acid ionomer was shown to stabilize the ink and also decrease the aggregation size. However, over long time periods (168 hrs) the aggregation size is independent of polymer loading, and approaches a steady state aggregation size around 350 nm. This equilibrium point suggests that the polymer is free to diffuse, adsorb, and relax within the excluded volume region. Furthermore, these results suggest that primary aggregates can be broken up with the addition of very low polymer loadings (15% I:C). A semi-empirical model is used to describe polymer|particle interactions within the ink, and the polymer coverage at the surface of the carbon was found to be the most sensitive parameter dictating ink stability. Finally, coating and rheology experiments are completed on all inks.

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“…The solvents are known to cause the PFSA to form colloids, improving ionic percolation. 34, 35 In this way, the PFSA should coagulate around the pre-dispersed catalyst to create a homogeneous catalyst ink. …”

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confidence: 99%

Electrocatalytic performance of fuel cell reactions at low catalyst loading and high mass transport

Zalitis

Kramer

Kucernak

2013

Phys. Chem. Chem. Phys.

180

194

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An alternative approach to the rotating disk electrode (RDE) for characterising fuel cell electrocatalysts is presented. The approach combines high mass transport with a flat, uniform, and homogeneous catalyst deposition process, well suited for studying intrinsic catalyst properties at realistic operating conditions of a polymer electrolyte fuel cell (PEFC). Uniform catalyst layers were produced with loadings as low as 0.16 μg Pt cm -2 and thicknesses as low as 200 nm. Such ultra thin catalyst layers are considered 10 advantageous to minimize internal resistances and mass transport limitations. Geometric current densities as high as 5.7 A cm -2 Geo were experimentally achieved at a loading of 10.15 μgPt cm -2 for the hydrogen oxidation reaction (HOR) at room temperature, which is three orders of magnitude higher than current densities achievable with the RDE. Modelling of the associated diffusion field suggests that such high performance is enabled by fast lateral diffusion within the electrode. The electrodes operate over a wide 15 potential range with insignificant mass transport losses, allowing the study of the ORR at high overpotentials. Electrodes produced a specific current density of 31 ± 9 mA cm -2Spec at a potential of 0.65 V vs. RHE for the oxygen reduction reaction (ORR) and 600 ± 60 mA cm -2 Spec for the peak potential of the HOR. The mass activities of Pt/C catalysts towards the ORR was found to exceed a range of literature PEFC mass activities across the entire potential range. The HOR also revealed fine structure in 20 the limiting current range and an asymptotic current decay for potentials above 0.36 V. These characteristics are not visible with techniques limited by mass transport in aqueous media such as the RDE. IntroductionUnderstanding the kinetics of the oxygen reduction reaction 25 (ORR) and hydrogen oxidation reaction (HOR) on platinum nano-particles is vital for polymer electrolyte fuel cell (PEFC) development. Each platinum nano-particle within the electrode should have optimal proton access, gas access and an electronic path to study intrinsic electrocatalytic properties of the catalyst. 30 These three criteria should be maintained throughout the working conditions (e.g., temperature, humidity and potential). If a reaction site is starved for any of the three, its activity will be reduced, which skews the average activity and introduces an error. It is paramount to minimize the number of underperforming 35 catalyst sites to determine intrinsic catalyst properties. Ideally, the catalyst layer should be made as thin as possible. Thus, all the catalyst particles will be close to the perfluorosulfonic acid (PFSA) membrane for ionic access and close to the gas diffusion layer (GDL) for gas access and an electronic path, removing 40 internal limitations. Mass transport limitations lead to concentration polarization across thick electrodes, 1-3 limiting the active thickness to about 5 μm at high current densities, regardless of how thick the catalyst layer is. 1 The majority of ORR and ...

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New Preparation Method for Polymer‐Electrolyte Fuel Cells

Cited by 304 publications

References 2 publications

Fuel cell catalyst layers containing short-side-chain perfluorosulfonic acid ionomers

Fuel cell catalyst layers containing short-side-chain perfluorosulfonic acid ionomers

Catalyst Layer Ink Interactions That Affect Coatability

Electrocatalytic performance of fuel cell reactions at low catalyst loading and high mass transport

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