CALCULATION OF CONDUCTIVITY AND POLARIZATION RESISTANCE OF COMPOSITE SOFC ELECTRODES FROM RANDOM RESISTOR NETWORKS

A model for total conductivity and polarization resistance of composit e electrodes in solid oxide fuel cells is proposed. The model is based on numerically solving Kirchoff's current law for the resistor networ k resulting from scattering predetermined fractions of electrode and e lectrolyte particles at random on the sites of a three-dimensional cub ic lattice. The model predicts an almost abrupt rise in total conducti vity at an electrode-particle volume-fraction of 0.3, and a polarizati on resistance with a relatively broad minimum close to this percolatio n threshold, in good agreement with experimental results.