Proton‐Conducting Amorphous Alumina Electrolytes for Low‐Temperature Ceramic Fuel Cells

The development of high‐performance electrolytes enabling rapid ionic transport represents a critical pathway for operational temperature reduction in solid oxide fuel cells (SOFCs). This study introduces amorphous alumina (AlO x ) as a novel electrolyte material, systematically investigating its structural characteristics and charge transport mechanisms through comparative analysis with crystalline alumina (α‐Al 2 O 3 , γ‐Al 2 O 3 ) and conventional gadolinium‐doped ceria (GDC). It is found that AlO x possesses a notable enrichment of oxygen vacancy concentration. Its unique disordered atomic configuration plays a vital role in facilitating multiple pathways to enable fast ionic transport, resulting in high ionic conductivity of 0.08–0.12 S/cm at 480–540 °C, as evidenced by electrochemical impedance spectroscopy (EIS), which is one order of magnitude superior to its crystalline counterpart. When implemented in symmetrical SOFC configurations, the AlO x electrolyte demonstrates unprecedented power density of 677 mW/cm 2 at 540 °C. Further distribution of relaxation times (DRT) analysis confirms the predominance of protonic conduction pathways in AlO x while providing discernment of its electrochemical sub‐processes. This work thus provides a new advanced electrolyte for low‐temperature SOFCs while providing insights into amorphous ceramic.