Uniform catalyst infiltration into the Ni–YSZ electrode of solid oxide electrolysis cells via piezoelectric valve jet printing for enhanced performance and durability

Abstract

Non-uniform catalyst infiltration limits the translation of lab-scale solid oxide electrolysis cells (SOECs) to large-area devices. We demonstrate a piezoelectric valve-jet process to uniformly introduce Fe–GDC catalysts into Ni–YSZ-supported SOEC fuel electrodes. By varying droplet volume (0.1–5 µL) and jetting pressure (0.5–1.5 bar) at fixed areal liquid loading, we quantify penetration depth, center-edge uniformity, and agglomerate morphology. Small droplets (0.1–1 µL) suppress local overcrowding and yield more homogeneous catalyst distributions than micropipette infiltration and 5 µL valve-jet conditions. For 0.1 µL at 1 bar, Fe–GDC covers the surface uniformly and extends toward the functional layer, giving the best compromise between lateral uniformity and through-thickness penetration. Under H₂O/H₂ operation at 700 °C and 80% H₂O, this condition boosts the current density at 1.3 V by 28.9% relative to the non-infiltrated cell and lowers ohmic and polarization resistances, indicating reduced gas-diffusion and charge-transfer resistances. A 300 h galvanostatic test at 1 A cm⁻² shows the smallest voltage increase and better preservation of the Ni–YSZ backbone at the fuel-inlet, establishing small-droplet valve-jet infiltration as a scalable route to high-performance, durable SOEC fuel electrodes.