| Summary: | The direct methanol fuel cell (DMFC) with proton exchange membrane (PEM) as electrolyte and liquid methanol/water as the energy carrier is a promising power source for micro and various portable electronic devices (mobile phones, PDA’s, laptops and multimedia equipment). However a number of issues need to be resolved before DMFC can be commercially viable such as the methanol crossover and water crossover which must be minimised in portable DMFC’s. In the present work, a detailed experimental study on the performance of an «in-house» developed DMFC with 25cm2 of active membrane area, working near ambient conditions (ambient temperature and pressure) is described. Tailored MEAS (membrane electrode assemblies), with different structures and combinations of gas diffusion layers (GDL), were designed and tested in order to select optimal working conditions at relatively high methanol concentration levels without sacrificing performance. The experimental polarization curves were successfully compared with the predictions of a steady state, one-dimensional model accounting for coupled heat and mass transfer, along with the electrochemical reactions occurring in the DMFC recently developed by the same authors. The influence of the anode gas diffusion layer media, the membrane thickness and the MEA properties on the cell performance is explained under the light of the predicted methanol crossover rate across the membrane
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