Li1.3Al0.3Ti1.7(PO4)3 (LATP) solid electrolytes synthesized by microwave-assisted hydrothermal reactions for Li all-solid-state battery applications

Sub-micron LATP solid electrolytes have been prepared via a facile microwave-assisted hydrothermal method. The structure and ionic conductivity of LATP has been investigated as a function of hydrothermal synthesis temperature by powder X-ray diffraction (XRD), thermal analysis, scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). The hydrothermal synthesis temperature is pivotal in controlling the uniformity of the LATP particle size distribution and the surface morphology of the electrolyte. Optimal LATP pellets prepared from powder synthesized at 180 °C exhibit an ionic conductivity of 1.4 × 10−4 S cm−1 at 298 K, while variable temperature measurements yielded activation energy of 0.253 eV for Li diffusion. These favorable values could reflect the uniform particle size distribution, high crystallinity and a relative density as high as 97 %. The optimum electrolyte material was applied in an NCM523/LATP/Graphite pouch cell, which demonstrated a stable capacity (≥ 92.5 % at a Coulombic efficiency of ∼100 %) for >400 cycles. The results indicate that LATP synthesized by microwave-assisted hydrothermal methods performs very effectively as a solid electrolyte and is a credible candidate for all-solid-state LIBs.