High Li+ conduction in NASICON-type Li1+xYxZr2−x(PO4)3 at room temperature

The NASICON oxides with general formula Li 1+ x Y x Zr 2− x (PO 4 ) 3 (0.1 ≤ x ≤ 0.2) are prepared by conventional solid-state reaction. The samples are characterized by XRD, SEM, electrochemical impedance spectroscopy and 7 Li MAS NMR measurements. The structures are refined by the Rietveld method from powder X-ray diffraction data. With the introduction of Y 3+ , the volume of the large M1 cavity is reduced and the rhombohedral NASICON phase is stabilized at room temperature. The bulk and total Li + conductivities of Li 1.15 Y 0.15 Zr 1.85 (PO 4 ) 3 sintered by SPS are 1.4 × 10 −4 and 0.71 × 10 −4 S cm −1 at 25 °C, respectively; the activation energy is about 0.39 eV in the temperature range 300–473 K. • The rhombohedral NASICON Li 1+ x Y x Zr 2− x (PO 4 ) 3 (0.1 ≤ x ≤ 0.2) was stabilized at 25 °C. • The bulk conductivity of Li 1.15 Y 0.15 Zr 1.85 (PO 4 ) 3 were 1.4 × 10 −4 S cm −1 at 25 °C. • The activation energy was about 0.39 eV in the temperature range 300–473 K. • The dopant Y 3+ reduces the size of the interstitial space in the M1 cavity. • The size change in M1 and M2′ cavity facilitates the Li + transport.