Electrode Structure Effects on Current Up-Transient Operation in Polymer Electrolyte Fuel Cells

摘要

One of the key metrics for automotive fuel cell system is robust transient response to sudden changes in load and/or operating conditions. The complex dynamic response of a fuel cell is governed by transient charge, heat and mass transport effects occurring at various time scales. In recent years, the profound interaction between cell voltage response and water transport dynamics has been investigated under dynamic load change for a Pt/C electrode (1-3). Regarding cold start-up, subfreezing load transients attract significant interest (4-5). Investigations have shown that a sudden increase in current density under dry operation renders an instant voltage drop, commonly termed as voltage undershoot, due to anode dry-out. It was also found that a thinner membrane provides a lower voltage undershoot due to enhanced back diffusion of water.