Local Structure Distortion and Oxygen Substitution in Zr-Based Halide Nanocomposites: Key to Enhanced Ionic Conductivity for All-Solid-State Batteries

Designing highly conductive and (electro)chemically stable inorganic solid electrolytes (SEs) from cost-effective precursors is critical for developing all-solid-state batteries (ASSBs). Herein, we report a series of low-cost zirconium (Zr) -based halide nanocomposite SEs, Li1+2xZr1–xTaxO3xCl5–3x (x = 0.33, 0.4, 0.5), synthesized via mechanochemical interaction between LiTaO3 and ZrCl4. The optimized composition, Li1.8Zr0.6Ta0.4O1.2Cl3.8, exhibits enhanced ionic conductivity from 0.46 to 1.12 mS cm–1 and decreased electronic conductivity. Mechanochemical processing modulates the local structural environments of the halide nanocomposites, facilitating ion transport. Combined characterization, including X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and synchrotron X-ray absorption spectroscopy, reveals that oxygen-substituted nanocomposites with distorted local structures are key to improving ion transport. Finally, we demonstrate ASSBs using Li1.8Zr0.6Ta0.4O1.2Cl3.8 as the SE, single-crystalline LiNi0.8Co0.1Mn0.1O2 (scNCM811) as the cathode, and Li–In alloy as the anode, achieving stable cycling at room temperature and 1 C rate.