Thin Ba(Zr,Y)O 3 Coating Process by Chemical Solution Deposition for Anode-Supported Protonic Ceramic Electrochemical Cells

Lowering the operating temperature of the solid oxide electrochemical cells offers several advantages, including broader material availability, reduced start-up and shutdown time, and improved long-term reliability. Recently, protonic ceramic electrolyte materials have gained attention due to their higher ionic conductivity at intermediate temperature (500 – 750 ℃) compared to conventional oxygen ion-conducting ceramics. Additionally, protonic ceramic electrochemical cells have attracted interest for electrolysis application, as they can produce pure hydrogen from steam. However, the densification of protonic ceramic electrolyte materials requires higher temperatures (~1450 ℃ or even higher) than conventional oxygen ion-conducting materials, which can lead to secondary phase formation, evaporation of chemical species (especially Ba), and cell warping. In this study, we developed a chemical solution deposition (CSD) process for the gas-tight coating of BaZr 0.8 Y 0.2 O 3 (BZY) on a porous NiO/BZCYYb electrode surface of anode-supported cells, at temperatures below the maximum electrolyte processing temperature of 1200 ℃. A precipitation-free solution was synthesized by carefully mixing metal acetates, alkoxides, chelating agents, and solvents. The viscosity of the solution was modified by adding polyvinylpyrrolidone to ensure the formation of a thin BZY film without infiltration into the porous electrode. The solution was spin-coated onto a porous NiO/BZCYYb electrode and Si wafer for microstructural, electrochemical, and phase characterizations. It was revealed that a single-phase BZY film can be formed heat treatment temperatures above 700 ℃. Electrochemical evaluation and SEM analysis show that 2-micrometer gas-tight BZY film can be deposited on the porous NiO/BZCYYb electrode surface. Therefore, the developed CSD process can be a promising fabrication route for thin-film protonic ceramic electrochemical cells.