Ab initio study of the stabilities of and mechanism of superionic transport in lithium-rich antiperovskites

Recently, a family of halogen-based Li-rich antiperovskites were synthesized [J. Am. Chem. Soc. 134, 15042 (2012) (http://dx.doi.org/10.1021/ia305709z)]. and the measured superionic conductivity makes these materials promising candidates as solid electrolytes for applications in Li-ion and Li-air ba...

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Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2013-04, Vol.87 (13), Article 134303
Main Authors: Zhang, Yi, Zhao, Yusheng, Chen, Changfeng
Format: Article
Language:English
Subjects:
Activation
Condensed matter
Electronics
Energy gaps (solid state)
Mathematical analysis
Melting
Stability
Transport
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Summary:Recently, a family of halogen-based Li-rich antiperovskites were synthesized [J. Am. Chem. Soc. 134, 15042 (2012) (http://dx.doi.org/10.1021/ia305709z)]. and the measured superionic conductivity makes these materials promising candidates as solid electrolytes for applications in Li-ion and Li-air batteries. This discovery raises several pressing issues on the fundamental physics concerning the thermodynamic and electrochemical stability of the synthesized materials and the mechanism of the observed superionic Li+ transport. Here, we study the reported antiperovskites Li sub(3)OCI, Li sub(3) OBr, and their mixed compounds using first-principles density functional theory and molecular dynamics simulations. Our calculations show that these materials are thermodynamically metastable. Their large electronic band gaps and chemical stability against electrodes suggest the excellent electrochemical performance, which bodes well for the use in potentially harsh working conditions in practical battery applications. The calculated low activation enthalpy for Li-ion migration well below the crystal melting temperature and superionic transport near the Li sublattice melting state explain the experimentally observed phenomena. Our study identifies mobile Li vacancies and anion disorder as the primary driving mechanisms for superionic Li+ conductivity in the antiperovskites. This work unveils essential working principles of the Li-rich antiperovskites, which are crucial to further exploration, development, and application of these and other charge-inverted materials with tailored properties.
ISSN:1098-0121
1550-235X
DOI:10.1103/PhysRevB.87.134303