Limiting current behaviour of the direct methanol fuel cell

Limiting current density data for a liquid feed direct methanol fuel cell based on a Nafion(R) solid polymer electrolyte membrane are reported. The cell uses a membrane electrode assembly composed of porous Pt-Ru-carbon supported catalyst anode, Pt-carbon supported cathode covered by carbon cloth backing layers. The effect of cell temperature, air cathode pressure, methanol fuel flow rate, temperature and methanol concentration on the limiting current behaviour are described. Limiting current data are interpreted in terms of hydrodynamics and diffusion limiting effects in the porous catalyst structure and carbon cloth backing layers. In practical fuel cells the temperature of the feed and the cell are different due to heat transfer requirements and this factor is shown to influence performance. It is also demonstrated that cell operation is possible with a methanol solution vaporised into an inert gas stream. (C) 1999 Elsevier Science Ltd. All rights reserved.