PEM fuel cells have a characteristic relationship between voltage and current density. As load increases, voltage drops due to reaction kinetics, resistive losses, and mass transport limits.
Key operating variables
- Temperature: affects kinetics and water balance
- Humidity: impacts membrane conductivity and flooding risk
- Pressure: can improve performance but increases complexity and risk
- Stoichiometry / airflow: starvation damages cells
- Load profile: frequent transients and high peaks can accelerate wear
Common degradation mechanisms (high-level)
- Catalyst sintering/dissolution over time
- Carbon support corrosion (especially during start/stop cycles)
- Membrane chemical/mechanical degradation
- Contamination-driven performance loss
- Flooding/drying cycles that stress materials
Good practice themes
- Avoid repeated harsh start/stop cycles where possible
- Keep operation within recommended temperature/humidity ranges
- Ensure proper purging and water handling
- Use appropriate buffering (battery/supercap) for fast transients when required