Dense nanostructured solid electrolyte with high Li-ion conductivity by spark plasma sintering technique

Spark plasma sintering (SPS) technique has been attempted to prepare dense lithium ion conductors composed of nanostructured Li1.4Al0.4Ti1.6(PO4)3 with the NASICON-type structure. Typical 100% of theoretical density in the pellets was achieved for the sample by SPS at 650 °C, a much lower temperature compared to the solid-state sintering process. The ionic conductivity of 1.12 × 10−3 S/cm, the highest one for inorganic Li+-ion conductors as reported up to date was obtained at 25 °C with an activation energy (Ea) of 0.25 eV. The enhancement in ionic conductivity of the SPS pellets was supposed mainly due to the decrease in the particle size as well as the extremely high density of the samples.