Fabrication and Performance of Membrane Electrode Assembly Prepared by a Catalyst-Coated Membrane Method: Effect of Solvents Used in a Catalyst Ink Mixture

The effect of solvent types used to prepare catalyst-coated membrane (CCM) electrodes on the coating ink, applied coating process, interaction of catalyst ink and Nafion membrane and, thus, on the performance and power density of the proton exchange membrane fuel cells (PEM fuel cells) was investigated. Among seven types of solvents studied, the catalyst ink prepared using the isopropanol solvent showed the highest cell performance, followed in descending order by ethanol, acetone, water−ethylene glycol, ethylene glycol dimethyl ether (EGDME), and ethylene glycol diethyl ether (EGDEE). The superior performance was due to the good attachment of catalyst layer to membrane and the good surface coverage revealed by the results from the scanning electron microscope (SEM) of the CCMs, optical transmittance of the CCMs, and solvent absorption capacity of membrane. In electrode preparation by the CCM method, the solvent−ionomer mixture in solution form was more favorable than that in colloid form, as it gave higher cell performance. Finally, the catalyst-coated membrane on the H+ form Nafion demonstrated better power density than the CCM on the Na+ form Nafion.