Optimization of catalyst ink composition for the preparation of a membrane electrode assembly in a proton exchange membrane fuel cell using the decal transfer

For low interfacial resistance and feasibility of forming catalyst layer (CL), decal transfer (DT) is considered as one of the most effective methods for preparing a membrane electrode assembly. However, optimization of the catalyst ink composition is necessary, because of the complexity of the CL. Here, 1-propanol is adsorbed onto the CL coated onto the decal, as a swelling agent, for complete transfer of the CL onto Nafion membrane. Using this methodology, flat and complete DT is achieved at the hot-pressing conditions of 60 °C and 5 MPa. For optimization, the solvent-to-carbon ratio (SCR) and Nafion-to-carbon ratio (NCR) are controlled to achieve improved cell performance. In this study, by considering the morphology of CL and the cell performance when CL is annealed at temperatures sufficiently below the boiling point of the solvent, optimized SCR and NCR values of approximately 12.0 and 0.65, respectively, are obtained. In addition, microstructure, thickness and various electrochemical properties of the CLs are examined in detail.