Enhanced Performance of Protonic Ceramic Electrolysis Cells via Transient Sinterlayer Engineering

Protonic ceramic electrolysis cells (PCECs) are a promising technology for efficient hydrogen production at intermediate temperatures (500-600 °C), but their commercialization is hindered by fabrication challenges. In particular, the high-temperature sintering required to densify barium cerate-zirconate electrolytes promotes barium volatilization, leading to phase decomposition and degraded performance. Here, we introduce a transient sinterlayer processing strategy in which a thin (∼1 μm) surface coating is applied atop the electrolyte before sintering. During high-temperature processing, the sinterlayer suppresses electrolyte decomposition, promotes densification and grain growth, and is ultimately incorporated into the perovskite lattice, yielding a chemically uniform perovskite electrolyte. Three sinterlayer compositions (CeO2, La2O3, and La2Ce2O7) were evaluated for BaCe0.7Zr0.1Y0.1Yb0.1O3-δ electrolytes. La2O3 provided the greatest benefit by enhancing grain growth, preserving dopant distributions, and substantially improving stability upon exposure to boiling water, although degradation under CO2-containing conditions at 550 °C remained evident. Integrated into complete electrolysis cells, La2O3 sinterlayers increased current density by 67.2% at 1.3 V and 600 °C while improving Faradaic efficiency from 78.8 to 85.0% relative to a bare cell. These results establish transient sinterlayers as an effective fabrication strategy for high-performance PCECs.