Advancing solid-state lithium phosphate electrolyte: Synthesis and characterization of Li2NaPO4–ZrO2 nanocomposites for solid-state batteries

Lithium phosphates are one of the most promising groups of inorganic solid electrolytes under investigation owing to their excellent Li-ion conductivity. A series of compositions with different weight percentages of (1-x) Li2NaPO4-(x) ZrO2 samples have been prepared by the solid-state technique and characterized by FT-IR, XRD, SEM-EDS, TEM, and Impedance Spectroscopy. Among the various compositions, 20 wt % ZrO2 exhibits the highest ionic conductivity, i.e., σ = 4.5 × 10−3 Scm−1, and the lowest activation energy 0.0759 eV at 298 K. XRD analysis reveals that the addition of ZrO2 nano-filler up to the optimum value of 20 wt % suggests the formation of the amorphous phase. SEM micrographs reveal that the introduction of ZrO2 nanofiller reduces the crystallinity of the Li2NaPO4 and enhances the ionic conductivity compared with pure Li2NaPO4. Our study marks substantial advancement in the synthesis of innovative nanocomposite solid electrolytes for batteries with superior energy storage capacities. Graphical abstract caption: Graphical abstract for 20-LNPZ nanocomposite solid electrolyte. [Display omitted] •Li2NaPO4–ZrO2 nanocomposite with different wt. % of ZrO2 has been successfully synthesized by solid-state method.•The 20-LNPZ nanocomposite exhibited the maximum ionic conductivity of 4.5 × 10−3 Scm−1 at room temperature.•The introduction of ZrO2 nanofiller reduces the crystallinity of the Li2NaPO4 to a greater extent.•A simple synthetic procedure, improved ionic conductivity of the synthesized nanocomposite have promising potential for high-performance batteries.