The dispersion of perfluorinated sulfonic acid ionomers in catalyst inks is an important factor controlling the performance of catalyst layers in membrane electrode assemblies of proton exchange membrane fuel cells (PEMFCs). The effect of water/alcohol composition on the dispersion of H-Nafion in water/1-propanol and water/ethanol solutions was studied by dynamic light scattering (DLS), small-angle X-ray scattering (SAXS), and (19)F nuclear magnetic resonance ((19)F NMR) spectroscopy. Hydrodynamic radii calculated from DLS decay profiles and the radii and interparticle distance of rod-like particles derived from SAXS profiles showed almost the same dependence on alcohol concentration. 1-Propanol was more effective than ethanol to induce changes in the characteristic lengths of the rod-like particles. The motional narrowing in the (19)F NMR spectra by addition of 1-propanol indicates selective solvation of the rod-like particles. We suppose this might have decreased their radii and induced their elongation, which eventually led to extension of the ordered regions as observed in the hydrodynamic radii. Our study helps to clarify the dispersion of Nafion in aqueous alcohol solutions, which has implications for the performance of PEMFCs.

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The structure of solid polymer electrode and catalyst ink of fuel cell has been investigated by focusing‐ (FSANS) and contrast‐variation small‐angle neutron scattering (CV‐SANS). The solid polymer electrode, consisting of carbon (C), platinum, and ionomer (polymer, P), exhibited a power‐law function with two asymptotes, i.e., from I(q) ∼ q−1 to I(q) ∼ q−4 with a crossover around q ≈ 0.005 Å−1. The scattering functions of the catalyst ink, i.e., the polymer electrodes dispersed in water, were successfully decomposed to the corresponding partial structure factors, SCC(q), SPP(q), SCP(q), exclusively representing C‐C, P‐P, and C‐P correlations. SCC(q) was a monotonic decreasing function of q, dominating in the scattering from carbon clusters. On the other hand, SPP(q) exhibited a scattering maximum characteristic of polyelectrolyte solutions. This suggests that ionic clusters in polyelectrolyte solutions are formed in catalyst ink. The cross term, SCP(q), indicated that the carbon scattering is dominant and significant amount of ionomer is adsorbed on the carbon agglomerates. It is concluded that the catalyst ink consists of carbon agglomerates surrounded by ionomers and the presence of ionic‐cluster path plays a key role in the performance of the solid polymer electrodes in polymer electrolyte fuel cells. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39842.

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FC-Platform, specialized in PEFC's analysis and evaluation, has been launched as a NEDO's funded project. PF-Platform consists of 5 groups of the electrochemical evaluation, simulation, materials analysis, materials informatics and management, involves 21 institutions. An number of various materials research themes are also running in the NEDO's project. FC-Platform provides better direction of improving for these materials research by analysis and evaluation. Moreover, visualizing and predicting phenomena in the PEFCs are important for realizing high performance and durability at a material level. Therefore, we are focusing on advanced visualization techniques and multi-scale stack modeling development. We conducted analysis and evaluation of Gen2 MIRAI's MEAs and its materials employing developed analytics and modeling in this framework. This work was supported by a NEDO FC-Platform project commissioned by the New Energy and Industrial Technology Development Organization (NEDO). Toyota Motor Corporation supported for providing MIRAI's MEAs and materials.