Coupled Channel–Electrode Design for Water Transport and Performance Stability in Proton Exchange Membrane Fuel Cells

Water build-up has continued to be one of the leading causes of performance variability and loss of durability in proton exchange membrane fuel cells (PEMFCs), especially at the high current density and transient operating conditions. Whereas, flow-field design and microstructural optimization of electrodes have been highly investigated, the interactions between them have hardly been quantified, the combined channel-electrode transport mechanisms remain poorly measured. In the work, a combined channel-electrode microstructural engineering design is suggested to actively control the liquid water transportation and prevent the performance degradation through transport. A two-phase flow, species transport, charge conservation, heat transfer, and electrochemical kinetics Multiphysics model are solved at the channel-electrode interface using a fully coupled Multiphysics model. Systematic evaluation of quantitative transport indicators and stability indicators such as interfacial liquid water saturation, effective oxygen diffusivity, capillary pressure, hydrodynamic resistance, and voltage decay rate are done under operating conditions prone to flooding. These findings show that coordinated channel-electrode engineering leads to 20-35% reduced interfacial saturation of liquid water, 15-30% increased effective oxygen diffusivity at high current densities, and voltage fluctuation factor suppression up to 40 times higher than isolated channel- or electrode-only optimization strategies. In addition, flooding commences much later at much larger current densities with no huge penalty of pressure-drop. The findings prove that operational control is not the primary determinant of PEMFC water management, and that a coupled structure-property-transport relation is the fundamental determinant of water management in PEMFC, and that the microstructural transport behaviour that underlies electrochemical stability provides direct quantitative correlations between microstructural transport behaviour and overall flood resistance PEMFC architecture, and is offered as a robust materials-centric design pathway to flooding-resilient, high-load PEMFC architectures.