Ka. Striebel et al., STEADY-STATE MODEL FOR AN OXYGEN FUEL-CELL ELECTRODE WITH AN AQUEOUS CARBONATE ELECTROLYTE, Industrial & engineering chemistry research, 34(10), 1995, pp. 3632-3639
A mathematical model has been developed to describe the steady-state c
onstant-current operation of an oxygen cathode in aqueous carbonate el
ectrolyte, as might be used as a component of a direct-methanol fuel c
ell. The diffusion and reaction of oxygen in PTFE-bonded Pt-catalyzed
porous gas diffusion electrode agglomerates as well as Ohmic and migra
tion effects over the catalyst layer were taken into account. The mode
l accurately predicts the shape and the oxygen pressure dependence of
cathode polarization data for 2 and 4 M K2CO3 electrolyte, using no ad
justable parameters. Transport of OH- ions out of the catalyst layer i
s shown to be a limiting factor in the operation of these modern fuel
cell cathodes, which have been generally optimized for maximum oxygen
transport in the electrolyte. The model. indicates that higher catalys
t layer porosities and thinner electrodes would yield better cathode p
erformance in this electrolyte.