Mathematical model of a gas diffusion electrode bonded to a polymer electrolyte

TLDR

The study derives a mathematical model for an ion‑exchange membrane bonded to a gas‑fed porous electrode. The model simulates the oxygen electrode of a polymer‑electrolyte fuel cell, analyzing cell polarization, water transport, and noble‑metal catalyst utilization. The model predicts polarization behavior that matches experimental data, shows that membrane resistance dominates at high current densities, highlights ORR resistance across all practical currents, and reveals that water transport depends on pressure and electric‑potential forces.

Abstract

Abstract A mathematical model for an ion‐exchange membrane attached to a gas‐fed porous electrode is derived and discussed. The model is applied to simulate the oxygen electrode of a polymer‐electrolyte fuel cell. Our discussion focuses on cell polarization characteristics, water transport, and catalyst utilization—all of which must be considered for fuel‐cell design. Calculated polarization behavior is shown to compare favorably with published experimental data. Our results indicate that if the membrane maintains full saturation, its contribution to the total cell resistance is most significant at higher operating current densities (greater than 200 mA/cm 2 ). Polarization resistance due to the oxygen reduction reaction appears to be important for all practical current densities. Water transport, driven by pressure and electric‐potential forces, is shown to be a complicated function of the cell operating conditions. The utilization and distribution of noble‐metal catalyst is discussed.