Polarization Study of a Fuel Cell with Four Reference Electrodes

Abstract

The changes in the anode and cathode potentials of a phosphoric acid fuel cell under various conditions were studied using a single cell equipped with four reversible hydrogen electrodes located near the inlets and outlets. When pure hydrogen gas was used as a fuel, the polarizations under load were homogeneous in the plane of the cell. However, when the reformate gas was used, inhomogeneity in the plane arose under load. The cathode and anode potentials shifted in the positive direction at the fuel outlet area. The potential shifts increased with an increase of fuel utilization or due to poisoning. The voltage loss due to poisoning ( loss) caused an increase not only of the anode polarization but also of the cathode polarization in the fuel inlet area. The increase of cathode polarization at the fuel inlet area was due to current convergence into the fuel inlet area. The potential shifts at the fuel outlet can be attributed to the acidity change of electrolyte there. The local acidity change of electrolyte can arise from a local starvation of hydrogen and hence of protons.