Li—Co Dual‐Doped Ceria‐Based Composite as a Promising Low‐Temperature Electrolyte for Metal‐Supported Solid Oxide Electrolyzers

TL;DR

A new Li-Co doped electrolyte improves performance and lowers sintering temperatures in solid oxide electrolyzers for green energy.

Contribution

A Li–Co dual-doped GDC electrolyte is developed with enhanced sinterability and ionic conductivity for low-temperature SOECs.

Findings

Li–Co codoping reduces sintering temperature and improves grain connectivity in GDC.

The optimized sample achieves an ionic conductivity of 2.17 × 10−2 S cm−1 at 750 °C.

The electrolyte outperforms YSZ in electrochemical performance in symmetric SOECs.

Abstract

Solid oxide electrolysis cells (SOECs) are among the most efficient energy‐conversion devices for power‐to‐X applications in green energy technologies. Here, we report a high‐level (5 mol%) Li‐ and Co‐dual‐doped gadolinium‐doped ceria (GDC) electrolyte synthesized under an inert atmosphere, suitable for fabricating SOECs using conventional ferritic steel supports. The doped GDC exhibits uniform dopant incorporation and a single‐phase cubic fluorite structure, achieving 98.18% relative density at 950 °C. Dilatometry and microstructural analyses reveal that Li–Co codoping significantly reduces sintering temperature and improves grain connectivity. Time‐of‐flight secondary ion mass spectrometry shows a Li,Co‐rich surface layer whose thickness depends on sintering conditions, while Raman spectroscopy confirms the presence of a LiCoO2 phase and temperature‐dependent oxygen‐vacancy concentration. Electrochemical impedance spectroscopy demonstrates enhanced ionic conductivity, particularly for the sample sintered at 950 °C (denoted 5LC‐4), which achieves increases of 269.5% at 450 °C and 138.85% at 750 °C compared with commercial GDC. The ionic conductivity reaches 2.17 × 10−2 S cm−1 with an activation energy of 0.32 eV. A symmetric five‐layer SOEC integrating 5LC‐GDC exhibits superior electrochemical performance to yttria‐stabilized zirconia (YSZ) support, achieving a peak power density of 267.5 mW cm−2 at 850 °C.

Enhanced sinterability and ionic conductivity are achieved with Li and Co dual‐doped GDC electrolytes for metal‐supported solid oxide electrolyzers. The optimized sample shows 2.17 × 102 S cm1 at 750 °C, which typically approaches the superionic solid electrolyte conductivity ranges. A tubular cell fabrication and analysis demonstrated its potential as a high‐performance electrolyte for metal‐supported SOCs.© 2026 WILEY‐VCH GmbH

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