3D printed architected polymer/Ag/Pb lattice electrodes: Linking pore geometry to mass transport and electrochemical performance

Architected porous anodes offer a deterministic route to tune mass transport and interfacial electrochemistry in zinc electrowinning (Zn-EW) beyond conventional planar Pb electrodes. Here, layered polymer/Ag/Pb meta-structure anodes were fabricated by 3D printing of resin lattices with prescribed pore geometry (square, triangular, random) and pore density (4–10 pores per inch, PPI), followed by conformal electroless Ag metallization and pulse-reverse Pb electrodeposition. A pore-scale, geometry-derived dimensionless transport framework (Pe–Sh–Da) was combined with SEM, electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) in an industrial Zn-EW electrolyte to link architecture to Pb growth, accessibility, and passivation. Inferred from this theoretical dimensionless analysis and strongly corroborated by the experimental data, increasing PPI decreased Peclet and Sherwood numbers while increasing the effective Damköhler ratio, indicating a shift toward diffusion-dominated transport in confined pores; correspondingly, disc-like Pb nodule size increased (random lattice: 382±70 nm at PPI 4 to 826±159 nm at PPI 10). EIS showed strong architecture dependence: the triangular lattice at PPI 4 exhibited low polarization resistance (Rp ≈ 2.8 Ω) and high electrochemically active surface area (ECSA ≈ 4.8 cm -2 ), whereas tortuous random lattices reached Rp ≈ 10 4 Ω with ECSA <0.2 cm -2 , evidencing electrochemically inactive dead zones. CV further showed earlier, low-charge passivation on ordered lattices (triangular: +0.074 V vs Ag/AgCl) compared with bulk Pb (∼+0.68 V), alongside suppressed OER currents at high anodic bias. Overall, combining meta-structural design with pulse-reverse Pb coatings provides transferable design rules to reduce Pb usage while improving mass-transfer-limited performance and durability of Pb-based Zn-EW anodes.”