Synthesis and conductive properties of Li 1+xAl xTi 2-x(PO 4) 3 (x = 0, 0.3, 0.5) by sol-gel method

Abstract

Li 1+xAl xTi 2-x(PO 4) 3(LATP) is a promising solid electrolyte for all-solid-state Li ion batteries. In this study, LATP is prepared through a so-gel method using relatively the inexpensive reagents TiCl 4. The thermal behavior, structural characteristics, fractured surface morphology, ion conductivity, and activation energy of the LATP sintered bodies are investigated by TG-DTA, X-ray diffraction, FE-SEM, and by an impedance method. A gelation powder was calcined at 500°C. A single crystalline phase of the LiTi 2(PO 4) 3(LTP) system was obtained at a calcination temperature above 650°C. The obtained powder was pelletized and sintered at 900°C and 1000°C. The LTP sintered at 900~1000°C for 6 h had a relatively low apparent density of 75~80%. The LATP(x = 0.3) pellet sintered at 900°C for 6 h was denser than those sintered under other conditions and showed the highest ion conductivity of 4.50 × 10 -5 S/cm at room temperature. However, the ion conductivity of LATP (x = 0.3) sintered at 1000°C decreased to 1.81 × 10 -5 S/cm, leading to Li volatilization and abnormal grain growth. For LATP sintered at 900°C for 6 h, x = 0.3 shows the lowest activation energy of 0.42 eV in the temperature range of room temperature to 300°C.