Enhancing Mass Transport Efficiency in High‐Current Density PEMECs by Constructing Ti‐Fiber Oriented Porous Transport Layers

The efficiency of proton exchange membrane electrolysis cells (PEMECs) is much influenced by the dynamics of gas/liquid two-phase flow at the anode side, especially at high current densities. Among different components of PEMECs, the anode porous transport layers (PTLs) are essential for mass transfer optimization. In this work, novel titanium fiber PTLs are designed and fabricated by an angle-selective stacking method. Three oriented PTLs with 30°, 60°, and 90° stacking angles are fabricated and compared with commercial titanium felt. X-ray micro-computed tomography results indicate that the oriented PTLs can avoid dead zones. Electrochemical tests and computational fluid dynamics simulations demonstrate that the oriented PTLs can enhance oxygen expulsion, and decrease mass transport resistances at high current densities. The PEMEC with the 30° PTL exhibits the best performance, with polarization voltage and mass transport resistance decreased by ≈67 mV and 16 mΩ cm², respectively, compared to that of the commercial titanium felt at the current density of 3 A cm^-2. The current work provides a new perspective on enhancing the mass transport efficiency of PTLs by orderly arranging fibers.