Porous current collectors for passive direct methanol fuel cells

A passive direct methanol fuel cell (DMFC) with its cathode current collector made of porous metal foam was investigated experimentally. The measured polarization curves, constant-current discharging behavior and EIS spectra showed that the passive DMFC having the porous current collector yielded much higher and much more stable performance than did the cell having the conventional perforated-plate current collector with high methanol concentration operation. It was demonstrated that the improved performance for the porous current collector was attributed to: (i) the enhanced oxygen transport on the cathode as a result of a larger specific transport area, (ii) the increased operating temperature as a result of the lower effective thermal conductivity of the porous structure, and (iii) the faster water removal as a result of the capillary action in the porous structure, The experimental results also revealed that the porous current collector with a smaller pore size yielded higher performance as a result of the lower cell resistance. (c) 2006 Elsevier Ltd. All rights reserved.