Effect of the Inlet Gas Humidification on PEMFC Behavior and Current Density Distribution

Water management represents one of the main challenges in the design and operation of PEMFCs. The influence of inlet gas humidification on cell performances is analyzed in general and especially the effect of low humidity conditions in both cathode and anode is studied. Hereby in situ diagnostic tools like EIS and current density measurements are used.

Dry cathode air supply and a fully humidified anode gas stream lead to a periodic transition between low- and high-current cell operations. A review of the main variables involved in this phenomenology is given. Furthermore, this oscillatory behavior is used as a tool to study degradation processes.

Figure1  Overall cell current density oscillations (symbols) and current density distributions at the low current (lower inset) and high current (upper inset) states of a single PEM cell operated with dry cathode air supply (RH_c=5%) and a fully humidified anode gas stream (RH_a=100%); Cell voltage= 600mV, Flow H₂= 209 ml·min^-1, Flow Air= 664 ml·min^-1, Pressure= 1.5 bar,Tc=80°C