Effect of through-plane temperature gradient on water distribution in the anode gas diffusion layer for polymer electrolyte fuel cells

Temperature gradients across the catalyst-coated membrane influence water accumulation in the anode gas diffusion layer (GDL) of polymer electrolyte fuel cells, yet experimental investigations remain limited. This study systematically examines the impact of a through-plane temperature gradient on water distribution using operando synchrotron X-ray radiography. Lowering the anode temperature relative to the cathode causes increased water saturation in the anode GDL. This behavior is mainly due to phase-transition effects, specifically enhanced condensation and suppressed evaporation. A water saturation of 0.168 is observed in the under-rib regions of the anode GDL, which is relatively high compared to commonly reported values. These findings support the growing recognition that anode water accumulation can occur under certain temperature gradients, highlighting the crucial role of temperature gradients and the need for improved anode GDL designs in effective water management.