Lithium ion conductive glass ceramics in the system Li 1.4Al 0.4(Ge 1−xTi x) 1.6(PO 4) 3 ( x=0–1.0)

Abstract

Lithium ion conducting glass ceramics composed of the crystalline conductive phase Li 1.4Al 0.4(Ge 1−xTi x) 1.6(PO 4) 3( x=0–1.0) with the Nasicon-type structure have been synthesized and characterized by DTA, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and complex impedance techniques. The experimental results indicated that the glass ceramics were mainly composed of solid solution Li(Ge 1−xTi x) 2(PO 4) 3 formed by LiGe 2(PO 4) 3 and LiTi 2(PO 4) 3 in the whole x range and showed conductivity over 10 −4 S/cm at room temperature. The maximum room temperature lithium ion conductivity of 6.21×10 −4 S/cm with an activation energy as low as 0.32 eV was obtained for the Li 1.4Al 0.4(Ge 0.67Ti 0.33) 1.6(PO 4) 3 treated at 950 °C for 18 h. Mechanisms for the enhancement of σ totle in glass ceramics were given and discussed. The high conductivity, good chemically stability and easy fabrication of the Li 1.4Al 0.4(Ge 1−xTi x) 1.6(PO 4) 3 system suggest that they are promising solid electrolytes for all-solid state Li ion rechargeable batteries.