Origin of Potential Drops of Bipolar Polymer Electrolyte Membrane Fuel Cells in Constant Current Discharge

摘要

Empirical equations were developed to describe the potential-time behaviors of polymer electrolyte membrane fuel cell (PEMFC) stacks at constant current discharge. When either ambient temperature or discharge current is too high, the experimental potential-time curves are inclined or have fallen rapidly within a short discharge time. Various experimental potential-time curves are fitted well with the empirical equations at different discharge current and ambient temperatures. The effect of parameters of the empirical equations on the shape of the potential-time curve is also analyzed. Mass transfer is likely a reason for the rapid falling of the potential, and polymer electrolyte dehydration is responsible for the inclination of the potential-time curves. Empirical equations are helpful for forecasting and explaining the long-term discharge performance of the PEMFC stacks.