Redox Stability and Electrical Properties of a Series of Novel Quadruple Dopant BIMEVOX: Bi2V1−4x(CuNiNbTi)xO5.5−δ

Bi 2 VO 5.5 ‐based materials are well‐known oxide ion conductors owing to their exceptionally high ionic conductivity. However, their poor phase and redox stabilities under a reducing atmosphere hinder their practical application as electrolytes for solid oxide fuel cells. Here, a series of novel quadruple metal‐doped bismuth vanadium system materials Bi 2 V 1−4 x (CuNiNbTi) x O 5.5− δ (0 ≤ x ≤ 0.1) are prepared through a traditional solid state reaction method, aiming to enhance the phase and redox stability under reducing atmosphere. The results reveal that multiple‐metal‐doping can stabilize the tetragonal phase of Bi 2 VO 5.5 to room temperature and show good phase and structural stabilities under inert or high oxygen partial pressure atmospheres, as well as pure oxide ion conduction which is slightly lower than that of the parent material. However, under a reducing environment, the Bi 2 V 1−4 x (CuNiNbTi) x O 5.5− δ materials would still undergo a phase decomposition, yielding elemental bismuth impurity, and introducing strong electronic conduction. Thus, how to improve the phase and redox stabilities under the reducing atmosphere of the Bi 2 VO 5.5 ‐based materials is still the endeavor direction in the future.