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.