Calculation of optimum thickness of active layer of oxygen and air cathodes of fuel cell with Nafion and platinum

It is shown that, for the electrodes of fuel cells with solid polymer electrolyte, the dependence of overall current on the active layer thickness contains an extremum. There is an optimum thickness of active layer, at which the overall current reaches its maximum possible value. The nature of this dependence is explained. The character of the distribution of electrochemical process intensity over the depth of active layer of cathode with solid polymer electrolyte is analyzed. The optimum thicknesses of active layers of oxygen and air cathodes of fuel cells with Nafion and platinum and the corresponding overall currents and contents of catalyst in the active layer are calculated. In the calculations, the temperature of fuel cell, the pressure in the cathode gas chamber, and the cathodic potential were varied. The optimization of active layer thickness of cathode with solid polymer electrolyte can reduce the platinum consumption, i.e. its amount per 1 kW of power produced in a membrane-electrode assembly.