Limiting current behaviour of the direct methanol fuel cell

Limiting current density data for a liquid feed direct methanol fuel cell b ased on a Nafion(R) solid polymer electrolyte membrane are reported. The ce ll uses a membrane electrode assembly composed of porous Pt-Ru-carbon suppo rted catalyst anode, Pt-carbon supported cathode covered by carbon cloth ba cking layers. The effect of cell temperature, air cathode pressure, methano l fuel flow rate, temperature and methanol concentration on the limiting cu rrent behaviour are described. Limiting current data are interpreted in ter ms of hydrodynamics and diffusion limiting effects in the porous catalyst s tructure and carbon cloth backing layers. In practical fuel cells the tempe rature of the feed and the cell are different due to heat transfer requirem ents and this factor is shown to influence performance. It is also demonstr ated that cell operation is possible with a methanol solution vaporised int o an inert gas stream. (C) 1999 Elsevier Science Ltd. All rights reserved.