Thermal Hotspot Formation and Membrane Failure Mechanism Induced by Localized Bipolar Plate Oxidation in Proton Exchange Membrane Water Electrolysis

Thermal behavior in proton exchange membrane water electrolysis (PEMWE) affects stack safety and efficiency. This study investigates the electrothermal coupling behavior and failure mechanisms induced by localized bipolar plate (BP) oxidation through in situ segmented current mapping, temperature measurements, and 3D Multiphysics modeling. Results reveal that localized rib oxidation increases interfacial contact resistance, forcing current redistribution to adjacent regions and creating a heating belt. The low thermal conductivity of oxide and PEM impedes heat dissipation, generating thermal hotspots with temperature differences of up to 16 K at 6.0 A cm –2 . Stability tests using NR212 show that despite an apparently stable electrolysis voltage, H 2 Faradaic efficiency drops to ∼90%. This failure originates from PEM micro-perforation driven by a detrimental feedback loop of non-uniform electrical–thermal–mass distributions induced by localized oxidation. Two mitigation strategies are proposed, including enhancing the in-plane thermal conductivity of the porous transport layer (PTL) through bulk Pt coating and eliminating the PTL-BP interface via integrated sintering.