Layer-Specific Porosity Effects and Model-Driven Conditional Screening in Bilayer Ni–YSZ Fuel Electrodes

Bilayer Ni–YSZ fuel electrodes require layer-specific porosity design because support- and functional-layer porosities govern different transport, relative load-bearing, and electrochemical responses. We developed a through-thickness reduced-order model coupling Butler–Volmer kinetics, Bosanquet–Bruggeman layered mass transport, and a dimensionless relative load-bearing proxy. Paired porosity sweeps, four functional-layer porosity–activity mappings, and a 2000-member model ensemble were used for conditional multi-objective screening. The model was checked against a one-dimensional analytical reference and independently implemented in Python and MATLAB/Simulink. The maximum terminal-voltage deviation was 1.3 mV, and the two implementations agreed to double-precision numerical tolerance. The published curve and its approximately digitized counterpart showed the closest agreement over 0.2–0.5 A·cm−2; larger differences outside this interval were attributed to finite image resolution, line width, sparse sampling, and interpolation errors. Increasing support-layer porosity from 0.340 to 0.390 increased normalized effective diffusion by 22.85% but reduced the relative load-bearing proxy from 1.000 to 0.844. Functional-layer porosity produced a conditional low-activation-resistance region near 0.305. The screened candidate intervals were 0.3622–0.3630 for the support layer and 0.3041–0.3067 for the functional layer. These grid-resolved intervals are conditional screening outputs for subsequent validation, not validated design targets or manufacturing tolerances.