Design and testing of a passive DMFC planar system for portable applications

Direct methanol fuel cells are a promising alternative to batteries for portable electronic devices. Passive systems are systems where operation is possible without the use of auxiliaries, such as pumps, fans etc, resulting in a simpler and more reliable system. In this work a three cell planar passive direct methanol fuel cell system, operating at ambient conditions, has been designed and tested, pointing out the positive results and the negative issues of such configuration. The prototype has been tested and evolved into a second system with improved performances. In particular, the stack hardware has been realized through a PCB, with external connection for single cell testing. The electrodes where made starting from a standard ELAT electrode over carbon cloth. The catalyst is a JM Acetilene Black Pt/Ru 1:1 (wt%). The MEA has been assembled over a single Nafion 117 membrane and an expanded teflon gasket was used as sealant. The best performaces have been obtained using a 5 M CH3OH fuel in water and 4 mg/cm2 (Pt) . The results are 20 mW/cm2 at 0,2 V/cell and 100 mA/cm2. The biggest limitation has been methanol crossover through Nafion membrane, which resulted in low performance on both OCV and endurance testing. All the experiments have been performed at CNR-ITAE (Messina, ITALY)