Synthesis of Li1.3Al0.3Ti1.7(PO4)3-coated LiCoO2 cathode powder for all-solid-state lithium batteries

ABSTRACT In this study, water-based precursor solutions with citric acid as the chelating agent were prepared, and the effect of the pH of the precursor solutions on the morphology and microstructure of the Li1.3Al0.3Ti1.7(PO4)3 (LATP) coating layer was investigated. A clear precursor solution was prepared and its colour changed depending on the pH of the solution, suggesting that citric acid effectively formed chelate complexes composed of Li, Al, Ti and P ions. The scanning electron microscopy and energy-dispersive X-ray spectroscopy mapping analyses showed that a low pH resulted in a homogeneous LATP coating layer with a fine particle size and less dense morphology. When the pH value was increased, dense and enhanced surface coverage was obtained, whereas an inhomogeneous atomic distribution was confirmed in the LATP coating. The LATP-coated LiCoO2 (LCO) cathode exhibited enhanced specific capacity retention compared to that of the pristine LCO cathode.