Catalyst Layers Prepared By Mixing Ionomer Dispersions with Different Equivalent Weights in Proton Exchange Membrane Fuel Cells

Abstract

Recently, hydrogen-based energy conversion devices are stand out in the world for decarbonization. Fuel cells are common devices for hydrogen utilization, membrane electrode assembly (MEA) has the most important role in all components for fuel cell performance. MEA is consist of membrane and both side of catalyst layer, the catalyst layers were made of electrocatalyst and ionomer by evaporating all solvents in the catalyst inks. The ionomer increases the catalyst utilization by covering the electrocatalyst in the catalyst layer and increases the gas penetration by forming pore in the catalyst layer. Each ionomer dispersion has a different EW, and there are two types of side chains: Long side chain (LSC) and short side chain (SSC). Each ionomer has advantages and disadvantages. The structure of catalyst layer is formed differently according to type of ionomer, which could be make difference performance of catalyst layer. By mixing the ionomer, the advantages can be optimized to obtain a beneficial effect. Many properties of the components to consist of catalyst layers substantially influence their performance and durability due to the different interaction of electrocatalysts and ionomer. In this study, EW conducted an experiment to find out the difference in the properties of the catalyst layer using the same commercial ionomer and the ionomer made by mixing different dispersions. Three types of ionomers were used: i) long-side chain (LSC) ionomer, ii) short-side chain (SSC) and iii) Mixture of dispersions with different EW ionomer. Use an IEC automatic titrator to verify that ionomer dispersions made by mixing different ionomer dispersions have target EW values. Prepared catalyst layers prepared by the ionomers with different side chains were characterized by electrochemical evaluation such as I-V polarization, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and by physical and microscopic characterization such as porosimetry and water uptake. Acknowledgments This research was supported in part by the Hydrogen Energy Innovation Technology Development Program of the National Research Foundation (NRF) funded by the Ministry of Science, ICT ＆ Future Planning (NRF-2019M3E6A1063677) and by 2021 Green Convergence Professional Manpower Training Program of the Korea Environmental Industry and Technology Institute funded by the Ministry of Environment.