Defect-engineered lithium-coated BaTiO3 to enable high oxide-ion conduction in LT-SOFC

Solid oxide fuel cells (SOFCs) are emerging as transformative electrochemical energy conversion technologies owing to their superior efficiency, fuel versatility, and minimal environmental impact. Enhancing SOFCs for efficient performance at low temperatures (LT, 420–520 °C) requires electrolytes with superior ionic conductivity and extended stability. Here, we introduce lithium-coated BaTiO 3 (5%, 7%, and 10%, Li@BTO), demonstrating that varying the concentration yields surfaces that function as efficient pathways for ionic transport, as validated by X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR), electrochemical impedance spectroscopy (EIS), and coupled distribution of relaxation times (DRT) assessments. The highest-performing 7%Li-coated BTO electrolyte delivers a peak power density of 776 mW cm −2 and remarkable ionic conductivity of 0.144 S cm −1 at a low operating temperature of 520 °C. This research emphasises interfacial defect engineering as an effective approach to address the conductivity and longevity challenges of ferroelectric/dielectric perovskite electrolytes, demonstrating exceptional electrochemical performance and a pivotal structure-defect-transport paradigm for the activation of perovskite oxides, thus establishing a foundation for the methodical design of next-generation LT-SOFCs in a scalable context.