The electrode materials of Na-ion batteries must exhibit fast ion transport, a property that is often negatively impacted when mobile cations order. Many layered Na (and K) intercalation compounds adopt the P3 crystal structure, which tends to stabilize cation-vacancy orderings over a wide range of Na concentrations. The ordered phases have been predicted to consist of domains that are periodically separated by antiphase boundaries (APBs) to accommodate variations in Na concentration. The mechanisms and rates with which Na diffuses within such ordered phases of P3 are not understood. We have conducted a first-principles study of Na diffusion in the P3 structure, using Nax CoO2 as a model system. We find that most simple nearest-neighbor hops in Na-vacancy ordered phases in P3 result in unstable configurations and are therefore forbidden. We identify an alternative mechanism of Na transport that is mediated by APB migration via the formation and expansion of kinks along domain boundaries. The limiting kinetic barriers for this mechanism are quite low (0.03 to 0.30 eV). Vacancy defects are not required, and furthermore have formation energies that are higher than those of the APB kink defects. Furthermore, our results suggest that APB migration is a fundamental diffusion mechanism in the P3 structure.
Kaufman, Jonas L. and Van der Ven, Anton. "Antiphase boundary migration as a diffusion mechanism in a P3 sodium layered oxide." Physical Review Materials, vol. 5, no. 5, May. 2021. https://doi.org/10.1103/physrevmaterials.5.055401
Kaufman, Jonas L., & Van der Ven, Anton (2021). Antiphase boundary migration as a diffusion mechanism in a P3 sodium layered oxide. Physical Review Materials, 5(5). https://doi.org/10.1103/physrevmaterials.5.055401
Kaufman, Jonas L., and Van der Ven, Anton, "Antiphase boundary migration as a diffusion mechanism in a P3 sodium layered oxide," Physical Review Materials 5, no. 5 (2021), https://doi.org/10.1103/physrevmaterials.5.055401
@article{osti_1850163,
author = {Kaufman, Jonas L. and Van der Ven, Anton},
title = {Antiphase boundary migration as a diffusion mechanism in a P3 sodium layered oxide},
annote = {The electrode materials of Na-ion batteries must exhibit fast ion transport, a property that is often negatively impacted when mobile cations order. Many layered Na (and K) intercalation compounds adopt the P3 crystal structure, which tends to stabilize cation-vacancy orderings over a wide range of Na concentrations. The ordered phases have been predicted to consist of domains that are periodically separated by antiphase boundaries (APBs) to accommodate variations in Na concentration. The mechanisms and rates with which Na diffuses within such ordered phases of P3 are not understood. We have conducted a first-principles study of Na diffusion in the P3 structure, using Nax CoO2 as a model system. We find that most simple nearest-neighbor hops in Na-vacancy ordered phases in P3 result in unstable configurations and are therefore forbidden. We identify an alternative mechanism of Na transport that is mediated by APB migration via the formation and expansion of kinks along domain boundaries. The limiting kinetic barriers for this mechanism are quite low (0.03 to 0.30 eV). Vacancy defects are not required, and furthermore have formation energies that are higher than those of the APB kink defects. Furthermore, our results suggest that APB migration is a fundamental diffusion mechanism in the P3 structure.},
doi = {10.1103/physrevmaterials.5.055401},
url = {https://www.osti.gov/biblio/1850163},
journal = {Physical Review Materials},
issn = {ISSN 2475-9953},
number = {5},
volume = {5},
place = {United States},
publisher = {American Physical Society (APS)},
year = {2021},
month = {05}}
Krell Institute, Ames, IA (United States); Univ. of California, Los Angeles, CA (United States); Univ. of California, Oakland, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR). Scientific Discovery through Advanced Computing (SciDAC); USDOE Office of Science (SC), Basic Energy Sciences (BES)
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 243, Issue 866https://doi.org/10.1098/rsta.1951.0006
Kaufman, Jonas L.; Vinckevičiūtė, Julija; Krishna Kolli, Sanjeev
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol. 377, Issue 2152https://doi.org/10.1098/rsta.2019.0020