Novel yttrium and silicon co-doped Li1.3+x+yAl0.3−xYxTi1.7Siy(P1−yO4)3 solid electrolyte for lithium batteries: Effect on ionic conductivity and crystal structure

Abstract

Doping of superfast ionic conductors like NASICON has been shown to boost ionic conductivity and the efficiency of lithium batteries. NASICON-type yttrium and silicon-doped lithium aluminum titanium phosphate (LATP) solid electrolytes have been synthesized via the conventional solid-state method at different sintering temperatures. Their intrinsic physical, chemical, and electrochemical properties are analyzed using x-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. Yttrium and silicon co-doped LATP (LAYTSP) powder sintered at 900°C exhibits homogeneous hexagonal morphology and better crystallinity than the pure LATP solid electrolyte synthesized by the same methodology. LAYSTP demonstrated a higher ionic conductivity of 5.98 × 10⁻⁶ S/cm at ambient conditions. Mixing 5%-LiCl with LAYTSP-900°C improved the ionic conductivity significantly up to 1.88 × 10⁻⁴ S/cm. Cell viability testing demonstrated that our cells exhibit long-term stability and are suitable for applications requiring sustained high voltages.