Characterization of polymer electrolyte fuel cell (PEFC) active layer and experimental study of the water behaviour in a micro fuel cell

Miniaturized fuel cells are very attractive for portable power generation. CEA has developed a hydrogen micro fuel cell, operating at ambient conditions, in which external flows are free. Therefore, the problem of water management, which has been identified as crucial in fuel cells is dramatically increased in this miniaturized system. Since water is produced in the cathode, it is necessary to characterize this active porous layer, as well as to have a good understanding of the phenomena involved (water behaviour). Cathode structure, permeability and wettability have been determined, and structure heterogeneities have been investigated. Surface observation of a working fuel cell with a binocular and X-rays phase contrast microradiography experiments carried out at the European Synchrotron Radiation Facility reveal the heterogeneities of droplets formation within the cathode and at its surface and the major impact of relative humidity on the fuel cell operation. The impact of changes in the surface wettability is also shown.