Synthesis, Phases, and Ionic Conductivities of Multicomponent-Doped Na-β-Al2O3

The sodium-conductive ceramic Na-β-Al 2 O 3 serves as an indispensable solid electrolyte material in Na-S battery systems, primarily owing to its exceptional ionic transport properties for Na + ions coupled with remarkable resistance to thermal degradation. However, its limited conductivity at low temperatures restricts practical applications, necessitating strategies to enhance performance. In this paper, a series multicomponent-doped Na 2 Al 10−5 x (Li 2 x Mg x Zn x Ni x )O 16−3.5 x ( x ≤ 0.4) was synthesized through solid-state reaction method, with their phases, microstructures, and electrical properties being thoroughly studied. The results revealed that the highest ionic conductivity (1.2 × 10 −2 S/cm at 300°C) was achieved for the sample x = 0.1, which is five times higher than that of the parent material, significantly exceeding the undoped sample (2.38 × 10 −3 S/cm at 300°C). In addition, the sodium ion migration pathways in Na-β-Al 2 O 3 -based materials were investigated by the bond-valence-based method.