Performance optimisation of PEM fuel cell during MEA fabrication

We have analysed membrane electrode assemblies (MEAs) involving fabricated and commercially available electrodes using a scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) and developed simple mathematical models to simulate the best performance and design conditions. The analysis showed that a MEA surface with the catalyst layer consisting of 10 wt% Pt/C and 30,wt% Teflon((R)) (PTFE, designated E2) loaded with 0.38 mg Pt/cm(2) showed good localisation of the platinum particles. The SEM image of the E2 electrode showed the existence of a diffusion layer, while the cross-section of electrode E3 (without diffusion layer) showed only the backing layer of the carbon cloth. It was seen that good adhesion of the catalyst on the membrane was obtained as a result of the hot press used in fabrication. XPS analysis showed that the electrode surfaces consisted of C, O, F, Si and Pt, whose binding energies for the PTFE/C layer were C 1s, O 1s, F 1s and Si 2p states and were 285.0, 532.7,689.5 and 103.0 eV, respectively. While for the catalyst layer, the binding energies for the elements, C Is, 0 Is, F Is, Si 2p and Pt 4f states, were 284.3, 532.4, 689.3, 102.9 and 74.1 eV, respectively. Similar observations we, re made for a commercial E-TEK electrode. The mathematical and simulation investigations supported the hypothesis made in an earlier study in terms of optimum PEM fuel cell performance determination and design simulation. The calculated values of the voltage operational limit V-opl cal. agreed quite well with the experimental data V-opl exp. reported earlier. Other works from the open literature were also correlated using the mathematical model, and it was found that the V-opl values were comparable. Hydrogen usage thus calculated was best with the E2 electrode compared to El, E3 and the commercially available E-TEK electrode. (C) 2004 Elsevier Ltd. All rights reserved.