Preparation and characterization of the fast ion conductors of Li_8Al_(1-x)Si_(2x)P_(1-x)O_8 system

Lithium fast ion conductors of Li 8Al 1- x Si 2 x P 1- x O 8 which are based on an original unit of Li 4SiO 4 have been prepared by high temperature solid state reaction using pyrophyllite as starting material. X ray diffraction analysis indicated that a single solid solution phase with the P 2l /m space group was formed in the composition range of 0.5 x 0.9. The composition with x =0.6 possesses maximum ionic conductivity which reaches up to 2.5×10 -2 S/cm at 673K and its activation energy is 60.93kJ/mol (temperature range 373～673K).