Dynamic internal performance of PEMFC under fuel starvation with high-resolution current mapping: An experimental study

The fuel starvation in a proton exchange membrane fuel cell (PEMFC) during automotive operation conditions could lead to severe decay of the catalyst layer and performance degradation. As the fuel starvation occurs locally and induces uneven reverse current inside the fuel cell stack, it is critical to understand the dynamic mechanism of the fuel cell internal performance during the fuel starvation process. In this work, a self-developed segmented cell with 396 segments is applied to measure the transient current distributions inside the fuel cell stack with active area of 406 cm2. In the present experiment, the fuel starvation process is simulated by decreasing the H2 stoichiometric ratio from 1.5 to 1.0 and the dynamic performance is tested as the cell voltage drops to the shutdown values. The results show that the current density uniformity worsens significantly during the fuel starvation, even though the load current is kept stable. With the cell voltage decreasing from 0.5 V to -0.9 V in fuel starvation, the maximum local current around H2 inlet rises from 1.363 A/cm2 to 3.697 A/cm2 and the lowest current density near H2 outlet drops from -0.039 A/cm2 to -0.1 A/cm2 under the load current density of 0.5 A/cm2. The analysis of transient local current behaviors corresponding to the voltage reversal process is beneficial to optimize the control of PEMFC system and mitigate the performance degradation.