Direct methanol fuel cell stack for auxiliary power units applications based on fumapem®F-1850 membrane

Direct methanol fuel cells (DMFCs) have been actively investigated from both fundamentaland applied points of view due to their interesting perspectives for the applicationin the fields of auxiliary power supply and portable power sources. However, researchefforts are still needed to solve the drawbacks presently affecting these devices, such asmethanol cross-over constraints, high costs of materials, etc. The present paper addressesthese issues by using a new FUMATECH proton exchange membrane (fumapem®F-1850), characterized by a nominal equivalent weight of 1800, as the electrolyte, and lowelectrode noble metal loadings compared to the state of the art. A membrane-electrodeassembly (MEA) based on this membrane was investigated in a small area (5 cm2)direct methanol fuel cell at 60 C and compared to a benchmark Nafion® 115 membrane interms of performance and methanol cross-over. The F-1850 membrane showed a lowermethanol cross-over rate than Nafion® 115, despite a lower thickness of the fumapem®membrane. This allowed to obtain a higher performance (74 vs. 64 mW cm2) for the F-1850 membrane compared to Nafion® at ambient pressure. To study the scalability of theDMFC device and related components, the new membrane was integrated in large-areaMEAs (100 cm2) and investigated in a 5-cell and 10-cell pressurized stack based on a bipolardesign. The stack was tested at 75 C, 5 M methanol solution at the anode andpressurized oxygen (2 atm. rel.) at the cathode, giving a normalized power density per cellof about 130 mW cm2. The results obtained with the 10-cell stack showed a goodagreement with the performance recorded with the 5-cell stack, confirming the scalabilityof the DMFC device.]