Chemical shift reference scale for Li solid state NMR derived by first-principles DFT calculations

S S Köcher; P P M Schleker; M F Graf; R-A Eichel; K Reuter; J Granwehr; Ch Scheurer

doi:10.1016/j.jmr.2018.10.003

Chemical shift reference scale for Li solid state NMR derived by first-principles DFT calculations

J Magn Reson. 2018 Dec:297:33-41. doi: 10.1016/j.jmr.2018.10.003. Epub 2018 Oct 9.

Authors

S S Köcher¹, P P M Schleker², M F Graf³, R-A Eichel⁴, K Reuter⁵, J Granwehr³, Ch Scheurer⁵

Affiliations

¹ Chair for Theoretical Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstraße 4, 85747 Garching, Germany; Institute of Energy and Climate Research (IEK-9), Forschungszentrum Jülich, 52425 Jülich, Germany; Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 1-2, 52074 Aachen, Germany. Electronic address: simone.koecher@ch.tum.de.
² Institute of Energy and Climate Research (IEK-9), Forschungszentrum Jülich, 52425 Jülich, Germany; Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, 45470 Mülheim an der Ruhr, Germany.
³ Institute of Energy and Climate Research (IEK-9), Forschungszentrum Jülich, 52425 Jülich, Germany; Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 1-2, 52074 Aachen, Germany.
⁴ Institute of Energy and Climate Research (IEK-9), Forschungszentrum Jülich, 52425 Jülich, Germany; Institute of Physical Chemistry, RWTH Aachen University, Landoltweg 2, 52056 Aachen, Germany.
⁵ Chair for Theoretical Chemistry and Catalysis Research Center, Technische Universität München, Lichtenbergstraße 4, 85747 Garching, Germany.

PMID: 30347386
DOI: 10.1016/j.jmr.2018.10.003

Abstract

For studying electrode and electrolyte materials for lithium ion batteries, solid-state (SS) nuclear magnetic resonance (NMR) of lithium moves into focus of current research. Theoretical simulations of magnetic resonance parameters facilitate the analysis and interpretation of experimental Li SS-NMR spectra and provide unique insight into physical and chemical processes that are determining the spectral profile. In the present paper, the accuracy and reliability of the theoretical simulation methods of Li chemical shielding values is benchmarked by establishing a reference scale for Li SS-NMR of diamagnetic compounds. The impact of geometry, ionic mobility and relativity are discussed. Eventually, the simulation methods are applied to the more complex lithium titanate spinel (Li₄Ti₅O₁₂, LTO), which is a widely discussed battery anode material. Simulation of the Li SS-NMR spectrum shows that the commonly adopted approach of assigning the resonances to individual crystallographic sites is not unambiguous.

Keywords: Chemical shift; DFT simulations; Disordered materials; Ionic dynamics; Lithium NMR; Solid–state NMR.