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.