Transient phenomenon of step switching for current or voltage in PEMFC

The transient phenomenon of fuel cell with 5cm2 active area is investigated in this study by current density step increase and switching voltage under different conditions. It is found that there is an undershoot when the current density step increase is at the loading of 60% RH anode cathode, 3 stoic., 70°C, 15psi for automobile applications. The voltage is almost zero under 0.2 step increase to 1.0A/cm2 due to the H+ transport in membrane or H2/O2 in catalyst layer is almost used up. The undershoot phenomenon is more serious under gases stoichiometries of 3.0/3.0 when H2 is fully humidified due to low gas concentration or flooding on the electrode. This phenomenon would induce the degradation of fuel cell components.