Electrode protective barrier layers for molten carbonate confinement

Abstract

Summary Pure NiO or lithiated NiO with distinct Li/Ni atomic proportions (50/50—LN55 and 30/70—LN37) were tested as protective barrier layers (PBLs) to enhance the stability of LaCoO3 (LC) electrodes in cells with composite electrolytes (CEs) consisting of Gd‐doped ceria (CGO) and a eutectic mixture of Na and Li carbonates (NLCs). PBLs and LC layers were sequentially deposited by screen printing before firing at 700°C and 550°C, respectively, to yield symmetrical cells (LC|PBL|CE|PBL|LC). Electrochemical testing involved impedance spectroscopy measurements in air in the 500°C to 650°C range. Scanning electron microscopy combined with energy‐dispersive X‐ray spectroscopy (SEM/EDS) revealed that distinct PBLs possess uneven wetting tendency, with impact on the role of LC layers. The best electrode performance (0.55 Ω cm2 electrode area specific resistance at 550°C in air) was observed using the LN37 PBL, stable throughout endurance tests up to 200 hours. Possible electrode mechanisms consistent with experimental evidence suggest an active role of the molten phase as an intermediate provider of O2− transport between the electrode and CGO.

Optimization of safe doping level for enhanced CO2 flux in composite membrane

“…Although the oxide ionic conductivity of MIEC partially removes CO 2 from such a mixture of gases, the larger A-site cation of the often used perovskite reacts heavily reacts with the carbonate melt. 16,17 CO 2 (G)…”

“…Although the oxide ionic conductivity of MIEC partially removes CO 2 from such a mixture of gases, the larger A-site cation of the often used perovskite reacts heavily reacts with the carbonate melt. 16,17 CO 2 (G) + CO 3 = (MC) ↔ C 2 O 5 = (MC)CO 2 (G) + O = (S) ↔ CO 3 = (MC)where G, MC, and S represent the gas, molten carbonate, and solid ceramic phases of the composites. The forward reaction captures CO 2 on the feed side and releases it by a reverse reaction.…”