Impact of manufacturing processes on proton exchange membrane fuel cell performance

Commercial success for proton exchange membrane fuel cell (PEMFC) requires manufacturing of its core component, membrane electrode assembly (MEA), with consistent and reliable performance. In this study, three common methods for the MEA manufacturing are investigated systematically for their impact on the cell performance under consistent preparation and cell test conditions, including catalyst coated substrate (CCS), catalyst coated membrane (CCM), and low temperature decal method (LTDM). The variations in each of these methods studied include applying an extra Nafion layer, hot press, and Pt loading. It is found that MEA manufacturing process has a significant impact on the cell performance, and this impact is significantly affected by the Pt loading. At the high Pt loading of 0.5 mg/cm2, CCM without hot press involving gas diffusion layers (GDLs), referred to as CCM-Wo, results in the best performance with the maximum power density of 0.95 W/cm2, although both LTDM and CCS with an extra Nafion layer (hence called N-LTDM and N-CCS) are just slightly less with the maximum power density of 0.91 W/cm2. Hot press with GDLs is essential for CCS method to achieve a good performance, while it is not the case for CCM and N-LTDM. Applying an extra layer of Nafion on catalyst layers as in N-LTDM and N-CCS methods has a positive impact on the cell performance; whereas it is negative when it is applied on the membrane as in the N-CCM method. When the Pt loading is reduced to 0.125 mg/cm2 (75% reduction in the Pt loading), cell performance is reduced for all the MEAs made by the three methods, but significant reduction (about 75%) is observed for CCS method, while it is less than 30% for the other two methods. Therefore, care should be taken in the MEA manufacturing for MEAs with low Pt loadings.