Comparative Analysis of Fiber-Based and Powder-Based\nPorous Transport Layers in Water Electrolysis for Green Hydrogen

In\nthis work, sintered titanium powder porous transport layers\n(PTLs) and titanium fiber PTLs are systematically investigated and\ncompared. The stochastic reconstruction method for 3D PTLs, morphological\nand topological characterization, pore-scale modeling (PSM), and Lattice\nBoltzmann method (LBM) are employed to comprehensively examine the\nbulk properties, surface properties, transport parameters, and oxygen\nremoval for two types of PTLs. A parametric PTL matrix consisting\nof two types of PTLs, each with different mean pore sizes and porosity,\nis selected for analysis. The results illustrate the substantial difference\nfor the properties obtained for PTLs depending on the material and\nstructural characteristics. Powder PTLs feature more homogeneous structural\nand transport properties (electrical and thermal conductivity) in\ncomparison to fiber PTLs. PTLs with lower porosity and lower mean\npore size exhibit superior surface properties and higher electrical\nand thermal conductivity but are not favorable for efficient oxygen\nremoval. In order to weigh the kinetic overpotential, ohmic overpotential,\nand mass transport overpotential, double-layer PTLs are constructed\nwith the aim of balancing interfacial contact, electrical and thermal\nconductivity, and oxygen transport. The impact of the thickness ratio\nis elaborated and further optimization strategies are also provisioned.\nThis work provides insights and references for a better understanding\nof the properties of PTLs and offers practical guidelines for the\ndesign and application of PTLs in commercial large-scale water electrolyzers.