Chronoamperometric Investigations of the Electrode-Electrolyte Interface of a Commercial High Temperature PEM Fuel Cell

This paper presents investigations into the chronoamperometric experiments performed on polybenzimidazole/phosphoric acid based high temperature polymer electrolyte membrane fuel cells. Electrolyte loadings in the membrane electrode assembly are varied to realise three different degrees of flooding of the electrode. Steady state as well as dynamic measurements at three different temperatures (160, 120 and 80 degrees C) is made via chronoamperometry on these cells. The transient current behaviour resulting from a voltage step change from open circuit voltage (similar to 1 V) to low voltages (0.1 V) are recorded and analysed. Analysis using the Cottrell plot depicts the underlying mass transport processes in the three different electrodes, catalyst utilisation as well as a better description of the three phase boundary reaction zone. An extension of the Cottrell equation is deduced to describe a regular commercial fuel cell behaviour.