Superior ionic conductivity of Zr–doped LiTa2PO8 ceramics

The recently discovered LiTa2PO8 ceramic material holds promise as a solid electrolyte for all–solid–state batteries. In this study, comprehensive characterization techniques, including XRD, MAS NMR, Raman spectroscopy, TMA, SEM/EDX, IS, DC potentiostatic polarization and Archimedes principle, were employed to investigate the influence of varying concentrations of Zr dopant on the electrical, microstructural, and structural properties of doped LTPO ceramics. Remarkably, the highest total ionic conductivity was observed for the LTPO–0.05Zr ceramic, reaching 0.92 mS/cm at 30°C. Moreover, the grain conductivity values remained consistently around 1.6 mS/cm, irrespective of the Zr dopant concentration. Microstructural and phase purity analyses revealed that the content of secondary phases significantly impacted the total ionic conductivity. The presence of glassy LiZr2(PO4)3 material appeared to positively influence the electrical properties of the LTPO–Zr ceramics. A discussion about the accurate location of zirconium within the material was performed.