Boosting electrochemical performance in SOCs via Cu-activated La-doped CeO2 “oxygen provider” interlayer with superior oxygen storage capacity

Abstract

Solid oxide cells (SOCs) are a cornerstone of the emerging hydrogen economy, yet their practical deployment remains constrained by performance degradation under high-current conditions and load fluctuation tolerance. Among recent solutions, the use of high oxygen storage capacity (OSC) materials as an ‘oxygen provider’ has shown promise, but their implementation is hindered by high-temperature fabrication that induces detrimental interfacial reaction. Here, we introduce a cost-effective and scalable strategy that resolves this long-standing challenge by incorporating a minute amount (0.25 wt %) of copper (Cu) into La-doped CeO2 (LDC). The Cu additive enables the fabrication of a dense and chemically stable LDC interlayer at a significantly reduced sintering temperature of under 1100 °C, simultaneously enhancing its oxygen storage and electrochemical capacitance. This approach not only prevents impurity formation by lower sintering condition but, more importantly, activates superior oxide-ion transport and oxygen-providing capability by significantly boosting the interlayer's OSC and interfacial electrochemical capacitance between the electrolyte and air electrode. The resulting LDC-Cu layer exhibits a remarkable enhancement in oxide-ion transport, achieving a higher oxygen storage capacity of 125 μmol [O2]/g at 800 °C and a peak power density of 2.3 Wcm−2, It far surpasses conventional LDC and GDC counterparts while markedly improving stability under high current loads. This work establishes a practical and commercially viable route to fabricating high-performance SOCs, providing new insight into the design of oxygen-active interlayers for advanced electrochemical energy systems. © 2026 The Authors