Study of membrane electrode assemblies for direct methanol fuel cells

At DLR, membrane electrode assemblies (MEA) for direct methanol fuel cells (DMFC), are produced with the company's own dry production technique. For improving this production technique, the MEAs in fuel cells are characterized electrochemically in fuel cell test facilities as well as physically by scanning electron microscopy (SEM). In order to measure the local current densities in polymer electrolyte membrane fuel cells, a method has been developed at DLR and tested in fuel cells supplied with hydrogen as fuel. For the DMFC, a measuring cell with 16 segments was built for examining MEAs with an overall active electrode area of 25 cm. With a sufficient resolution of location and time, simultaneous measurement of different local current densities in the cell can be carried out thus accelerating and improving operating parameter studies. This new tool is used at DLR for characterizing and developing improved MEAs and for examining the cell design (e.g. flow fields) and operating conditions of DNTC. In the measuring cell with its segments, the local mass conversion rates in the DMFC for liquid methanol-water mixtures are examined. (C) 2002 Elsevier Science B.V. All rights reserved.