Computational insights into the superionic behavior of amorphous lithium oxyhalide 1.6Li2O-TaCl5 solid electrolyte

Inorganic solid electrolyte (SE)-based all-solid-state batteries have attracted huge attention as a potential next-generation energy storage technology. Among them, halide compounds are especially interesting candidates for SEs owing to their remarkable ionic conductivity (≥ 11 mS cm −1 ) at room temperature, great oxidation stability and deformability. This work presents a sophisticated computational approach to examine the phase stability, ionic conductivity, electrochemical behavior and compatibility with typical cathode materials, of lithium oxyhalide (1.6Li 2 O-TaCl 5 ; named as LOTC) which has exhibited an excellent ionic conductivity (∼13.8 mS cm −1 ) at room temperature. Different from the prevailing mechanisms based on concerted Li-ion motions and rotations of anions, vibrations of Cl − anions and dynamic Li Cl interactions via Li Cl networks are key to the fast movement of Li-ions in amorphous LOTC. The results also indicate that the LOTC structure is thermodynamically metastable and the interface of LOTC with LiFePO 4 and LiMn 1.5 Ni 0.5 O 4 cathodes exhibits significantly improved chemical stability. The results provide fresh insights for creating effective materials for solid-state technologies and demonstrate the potential of LOTC for use in high-performance energy storage systems. • Amorphous lithium oxyhalide offers high ionic conductivity (13.8 mS cm −1 ). • The amorphous structure leads to higher lithium-ion conduction. • The designed lithium oxyhalide is thermodynamically metastable. • However, it is electrochemically stable with LiFePO 4 and LiMn 1.5 Ni 0.5 O 4 .