Conformal Nanocoating at the Electrode–Electrolyte Interface for Active and Durable Solid Oxide Electrochemical Cells

Solid oxide electrochemical cells (SOECs) are promising energy conversion devices for efficient power generation and green hydrogen production. However, their widespread adoption has been hindered by limited performance, long-term durability, and the lack of scalable fabrication strategies to address these challenges. In this study, we present a practical and scalable approach to interface engineering through the conformal deposition of an ∼50 nm thick La_0.6Sr_0.4CoO₃ (LSC) nanocoating on a three-dimensional porous Gd_0.1Ce_0.9O_1.95 interlayer via electrostatic spray deposition. The conformal LSC nanocoating maximizes interfacial contact coverage and enlarges electrochemically active reaction sites, resulting in substantial performance enhancement. At 700 °C, the LSC-coated cell exhibits a peak power density of 1.46 W/cm² in the fuel cell mode and a current density of 1.78 A/cm² at 1.3 V in the electrolysis cell mode. Furthermore, the LSC nanocoating effectively mitigates the electrode-electrolyte delamination, maintaining stable operation during sequential high-current operation at 1.0, 1.5, and 2.0 A/cm² for 100 h at each current density. This work establishes a generalizable and manufacturable strategy for producing high-performance, durable, and industrially viable SOECs through scalable nanoscale interface engineering.