Atomistic insight into enhanced ionic conductivity in mixed halide sodium ion conductor Na3YClxBr6-x

TI Ri and KC Ri and IJ Kim and JR Hwang and CJ Yu, APPLIED PHYSICS LETTERS, 126, 203904 (2025).

DOI: 10.1063/5.0257157

Exploring solid-state electrolytes with high ionic conductivity and low electronic conductivity is of great importance in realizing all-solid- state batteries. Here, we provide an atomistic insight into the enhancement of Na ionic conductivity in mixed halides Na3YClxBr6-x (NYCBx) using ab initio calculations and machine-learning interatomic potential-based molecular dynamics simulations. Our calculations reveal that the electronic conductivity decreases as the Cl content increases, while the Na ionic conductivity reaches the highest value in NYCB3 with a middle content. Through analysis of phonon density of states, halogen mixing is found to cause a large distortion of metal-halogen polyhedra and superposition of cation and anion sublattice vibrations, leading to high Na ionic mobility.

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