Issue 46, 2021

Phase-structure-dependent Na ion transport in yttrium-iodide sodium superionic conductor Na3YI6

Abstract

All-solid-state sodium-ion batteries that utilize inorganic superionic conductors show great potential in energy storage applications. However, suitable Na superionic conductors with desirable high ionic conductivities and cross-linked diffusion networks are still in their infancy. In this work, we systematically studied the structural stabilities and Na ion transport mechanisms of the halide-based Na superionic conductors with different phase structures using first-principle calculations and data mining techniques. The iodide-based Na3YI6 with C2/m, P[3 with combining macron]m1, and P[3 with combining macron]1c space groups possess fcc and hcp anion sublattices with stable octahedral Na occupations, differing from the reported fast-ion transport mechanism in the sulfide bcc anion ones with tetrahedral Na occupations. The Oct–Tet–Oct diffusion pathway and Na-site weighted phonon vibrational frequencies play crucial roles in the synergistic Na-ion transport capabilities, leading to Na ionic conductivities of 0.35, 0.18, and 9.1 × 10−3 mS cm−1 at room temperature and corresponding activation energies of 315.5, 351.1, and 454.0 meV for C2/m-Na3YI6, P[3 with combining macron]m1-Na3YI6, and P[3 with combining macron]1c-Na3YI6, respectively. Restricted by the decisive diffusion triangle, P[3 with combining macron]1c-Na3YI6 shows deficient Na-kinetic performance with one-dimensional blocked ion transport channels. The phase-structure-dependent ion transport networks involving Oct–Tet and Oct–Oct pathways broaden the diffusion channels and provide rational guidance for the experimental design of halide-based Na superionic conductors.

Graphical abstract: Phase-structure-dependent Na ion transport in yttrium-iodide sodium superionic conductor Na3YI6

Supplementary files

Article information

Article type
Paper
Submitted
20 Sep 2021
Accepted
01 Nov 2021
First published
02 Nov 2021

J. Mater. Chem. A, 2021,9, 26256-26265

Phase-structure-dependent Na ion transport in yttrium-iodide sodium superionic conductor Na3YI6

H. Huang, H. Wu, C. Chi, Y. Yang, J. Zheng, B. Huang and S. Wang, J. Mater. Chem. A, 2021, 9, 26256 DOI: 10.1039/D1TA08086E

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