DFT simulations of 7Li solid state NMR spectral parameters and Li+ ion migration barriers in Li2ZrO3. Issue 47 (26th April 2016)

• Record Type: Journal Article
• Authors: Ferreira, Ary R.; Reuter, Karsten; Scheurer, Christoph
• Is Part Of: RSC advances. Volume 6:Issue 47(2016)
• Page Start: 41015
• Page End: 41024
• Publication Date: 2016-04-26
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6ra03339c
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : Energy barriers for Li + migration in Li2 ZrO3 as well as GIPAW NMR isotropic spectral parameters for 7 Li were computed, aiming to provide guidance for the interpretation and prediction of spectra of more complex systems like materials for LIBs. Abstract : Lithium zirconate (LZO) is a prototype material for studies of Li + ion mobility with a wide range of possible applications such as a ceramic breeder for nuclear reactors, a reversible sorbent for carbon dioxide capture, a coating for cathodes and anodes or even directly as an anode material in lithium-ion batteries (LIBs). Solid state nuclear magnetic resonance (NMR) is a powerful experimental technique with the potential to provide microscopic insights into Li + ion dynamics in solid materials, in particular if combined with theory to interpret the measured spectra. We use first-principles atomistic simulations based on density functional theory (DFT) to investigate the Li + ion migration mechanisms in LZO. Computed barrier heights for several possible Li + ion exchange pathways are in very good agreement with the experimentally reported values and confirm the relevance of lithium vacancies for the observed Li + ion mobilities. Additionally, 7 Li NMR isotropic spectral parameters such as quadrupolar coupling constants and chemical shifts, can be obtained by the gauge-including projector-augmented-wave (GIPAW) method in very good agreement with the experimental values, underpinning the validity of the computational models. The close analysis of these spectral parameters shows a clear correlation to simple descriptors for the local structural environment of the Li + ions, opening up a pathway to further modelling based on computationally cheaper methods. We note, however, that there is also a consistently poor agreement with experimental data for 7 Li anisotropic properties like the asymmetry parameter of the electric field gradient (EFG) tensor, which calls for further theoretical method development in this field.