Oxide-based ternary composite solid-state electrolyte for next-generation lithium batteries

Abstract

Oxide-based solid electrolytes are gaining popularity among researchers owing to their great structural stability. In this work, a novel oxide-based ternary composite (AlPO₄-SiO₂-Li₄P₂O₇) electrolyte is synthesized via a conventional solid-state process with excellent water stability and high ionic conductivity. The crystallographic structure of ternary composite is confirmed using x-ray diffraction and has a significant effect on ionic conductivity. The thermogravimetric analysis result shows a 22.26 wt% loss in the region of 25°C to 900°C due to the evaporation of volatile constituents, including nitrates, carbonates, and moisture. Surface analysis results revealed compact morphology and low porosity with arbitrary grain sizes. Electrochemical impedance spectroscopy has been used to evaluate ionic conductivities. The Mn-ternary composite sintered at 900°C has shown ionic conductivity of 1.63 × 10⁻⁶ S/cm at ambient temperature. 8 wt%-LiBr enhanced the ionic conductivity up to 1.68 × 10⁻⁴ S/cm by significantly reducing the grain boundaries without high-temperature sintering. Results suggested the suitability of LiBr mixed ternary composites as a favorite candidate for lithium batteries in terms of safety, stability, and high ionic conductivity.