Mg-Ion Conduction in Antiperovskite Solid Electrolytes Revealed by <sup><b>25</b></sup>Mg Ultrahigh Field NMR and First-Principles Calculations
Magnesium-ion batteries hold the potential to outperform the energy density of lithium-ion batteries, given the divalent charge carried by each Mg<sup>2+</sup> cation, but remain in an early stage of development. Here, <sup>25</sup>Mg solid-state nuclear magnetic resonance (ssNMR) is used to gain insight into the local structure and Mg-ion dynamics of candidate Mg-ion solid electrolytes, the antiperovskites Mg<sub>3</sub>SbN and Mg<sub>3</sub>AsN. Using the highest available magnetic field (35.2 T) for high-resolution solid-state NMR, the largest <sup>25</sup>Mg quadrupole coupling constants (<i>C</i><sub>Q</sub>) yet measured of up to 22 MHz are reported and corroborated by first-principles calculations. Predicted <i>C</i><sub>Q</sub> values are shown to correlate with the antiperovskite's tolerance factor; thus, <sup>25</sup>Mg NMR linewidths can report on lattice distortions and phase stability of these antiperovskites. Variable-temperature <sup>25</sup>Mg NMR spectra demonstrate changes at elevated temperatures, ascribed to Mg-ion motional effects. <sup>25</sup>Mg <i>T</i><sub>1</sub> relaxometry measurements at ultrahigh field reveal a lower activation energy for the more distorted Mg<sub>3</sub>AsN phase, matching computational predictions of a lower energy barrier for Mg<sup>2+</sup> ion migration and suggesting that additional scrutiny of antiperovskites as Mg-ion conductors is warranted. Given the inherent challenges of <sup>25</sup>Mg NMR, this work demonstrates the benefits of combining ultrahigh field NMR spectroscopy, advanced pulse sequences, modern signal processing, and first-principles calculations to facilitate NMR of quadrupolar nuclei as a tool to probe the local structure and ion dynamics in beyond-Li battery materials.
Authors
- David M. Halat (ORCID: https://orcid.org/0000-0002-0919-1689)
- Saul H. Lapidus (ORCID: https://orcid.org/0000-0002-7486-4325)
- Grant C. B. Alexander (ORCID: https://orcid.org/0000-0002-6041-4737)
- Baris Key (ORCID: https://orcid.org/0000-0002-1987-1629)
- Donald J. Siegel (ORCID: https://orcid.org/0000-0001-7913-2513)
- Harris E. Mason (ORCID: https://orcid.org/0000-0002-1840-0550)
- Jordi Cabana (ORCID: https://orcid.org/0000-0002-2353-5986)
- Kwangnam Kim (ORCID: https://orcid.org/0000-0003-1149-1733)
- Jeong Seop Yoon (ORCID: https://orcid.org/0000-0002-9002-094X)
- Ivan Hung (ORCID: https://orcid.org/0000-0001-8916-739X)
- Adam R. Altenhof (ORCID: https://orcid.org/0000-0002-8095-6373)
- Jeffrey A. Reimer (ORCID: https://orcid.org/0000-0002-4191-3725)
- Amrit Venkatesh (ORCID: https://orcid.org/0000-0001-5319-9269)
- Zhehong Gan (ORCID: https://orcid.org/0000-0002-9855-5113)
- Xiao-Ling Wang (ORCID: https://orcid.org/0000-0002-8718-0408)
- Haoyu Liu (ORCID: https://orcid.org/0000-0002-6741-7295)
Institutions
- Florida State University (US)
- Argonne National Laboratory (US)
- Lawrence Livermore National Laboratory (US)
- Los Alamos National Laboratory (US)
- Lawrence Berkeley National Laboratory (US)
- Colorado School of Mines (US)
- California State University, East Bay (US)
- University of Michigan (US)
- Mineral Products Association (GB)
- University of Illinois Chicago (US)
- Division of Chemistry (US)
- Division of Materials Science and Engineering (AU)
- National High Magnetic Field Laboratory (US)
- Walker (United States) (US)
- Advanced Photon Source
- The University of Texas at Austin (US)
- University of California, Berkeley (US)
Publication Details
- Journal
- Journal of the American Chemical Society
- Published
- 2025-07-24
- DOI
- https://doi.org/10.1021/jacs.5c07442
- Citations
- 2
- Primary Topic
- Thermal Expansion and Ionic Conductivity
- Type
- article
- Field-Weighted Citation Impact
- 1.04
Funders
- U.S. Department of Energy
- National Institutes of Health
- National Nuclear Security Administration
- Division of Materials Research
- Basic Energy Sciences