Effects of Accumulated Water on Power Increase after PEFC Cold Startup

For cold startup of a polymer electrolyte fuel cell (PEFC), rapid output increase after the temperature rise is a critical issue. This study investigated experimentally the effective cell structure for this issue. In the experiment, we used an adiabatic cell to simulate the temperature rise of the stack by using separators with a small heat capacity and insulation material around it. The sub-zero startup with the cell with 1.0 mm wide channel and rib was successful from –10 ℃, but the shutdown occurred immediately due to flooding after the load increase. In the power increase with 0.3 mm wide channel and rib, it was shown that the cell voltage with 0.3mm wide channel and rib becomes more stable after the load increase than with the 1.0 mm wide channel and rib. This indicates that the narrow rib and channel is effective to improve the rapid power increase after the cold startup. This is considered because the liquid water is less likely to accumulate at the interface between MPL and CL in the cell with 0.3 mm wide channel and rib.