Lithium ion conductive glass ceramics in the system Li1.4Al0.4(Ge1−xTix)1.6(PO4)3 (x=0–1.0)

Lithium ion conducting glass ceramics composed of the crystalline conductive phase Li1.4Al0.4(Ge1−xTix)1.6(PO4)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(Ge1−xTix)2(PO4)3 formed by LiGe2(PO4)3 and LiTi2(PO4)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 Li1.4Al0.4(Ge0.67Ti0.33)1.6(PO4)3 treated at 950 °C for 18 h. Mechanisms for the enhancement of σtotle in glass ceramics were given and discussed. The high conductivity, good chemically stability and easy fabrication of the Li1.4Al0.4(Ge1−xTix)1.6(PO4)3 system suggest that they are promising solid electrolytes for all-solid state Li ion rechargeable batteries.