A systematic study of 25Mg NMR in paramagnetic transition metal oxides: Applications to Mg-ion battery materials

Jeongjae Lee; Ieuan D. Seymour; Andrew J. Pell; Siân E. Dutton; Clare P. Grey

doi:10.1039/c6cp06338a

A systematic study of ²⁵Mg NMR in paramagnetic transition metal oxides: Applications to Mg-ion battery materials

Jeongjae Lee, Ieuan D. Seymour, Andrew J. Pell, Siân E. Dutton, Clare P. Grey^*

^*Corresponding author for this work

Chemistry

Research output: Contribution to journal › Article › peer-review

46 Citations (Scopus)

Abstract

Rechargeable battery systems based on Mg-ion chemistries are generating significant interest as potential alternatives to Li-ion batteries. Despite the wealth of local structural information that could potentially be gained from Nuclear Magnetic Resonance (NMR) experiments of Mg-ion battery materials, systematic ²⁵Mg solid-state NMR studies have been scarce due to the low natural abundance, low gyromagnetic ratio, and significant quadrupole moment of ²⁵Mg (I = 5/2). This work reports a combined experimental ²⁵Mg NMR and first principles density functional theory (DFT) study of paramagnetic Mg transition metal oxide systems Mg₆MnO₈ and MgCr₂O₄ that serve as model systems for Mg-ion battery cathode materials. Magnetic parameters, hyperfine shifts and quadrupolar parameters were calculated ab initio using hybrid DFT and compared to the experimental values obtained from NMR and magnetic measurements. We show that the rotor assisted population transfer (RAPT) pulse sequence can be used to enhance the signal-to-noise ratio in paramagnetic ²⁵Mg spectra without distortions in the spinning sideband manifold. In addition, the value of the predicted quadrupolar coupling constant of Mg₆MnO₈ was confirmed using the RAPT pulse sequence. We further apply the same methodology to study the NMR spectra of spinel compounds MgV₂O₄ and MgMn₂O₄, candidate cathode materials for Mg-ion batteries.

Original language	English
Pages (from-to)	613-625
Number of pages	13
Journal	Physical Chemistry Chemical Physics
Volume	19
Issue number	1
DOIs	https://doi.org/10.1039/c6cp06338a
Publication status	Published - 11 Nov 2016

Bibliographical note

Funding Information:
Via our membership of the UK's HEC Materials Chemistry Consortium, which is funded by EPSRC (EP/L000202), this work used the ARCHER UK National Supercomputing Service (http://www.archer.ac.uk). Research was also carried out at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886. J. L. acknowledges Trinity College Cambridge for the graduate studentship. I. D. S. acknowledges the Geoffrey Moorhouse Gibson Studentship from Trinity College Cambridge. A. J. P. acknowledges the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy under Contract DE-AC02-05CH11231, under the Batteries for Advanced Transportation Technologies (BATT) Program Subcontract 7057154. We thank Dr Derek Middlemiss for helpful discussions and providing a copy of the mean field magnetism code, and Dr Dinu Iuga for helpful advices on DFS experiments.

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© the Owner Societies 2017.

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10.1039/c6cp06338a

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title = "A systematic study of 25Mg NMR in paramagnetic transition metal oxides: Applications to Mg-ion battery materials",

abstract = "Rechargeable battery systems based on Mg-ion chemistries are generating significant interest as potential alternatives to Li-ion batteries. Despite the wealth of local structural information that could potentially be gained from Nuclear Magnetic Resonance (NMR) experiments of Mg-ion battery materials, systematic 25Mg solid-state NMR studies have been scarce due to the low natural abundance, low gyromagnetic ratio, and significant quadrupole moment of 25Mg (I = 5/2). This work reports a combined experimental 25Mg NMR and first principles density functional theory (DFT) study of paramagnetic Mg transition metal oxide systems Mg6MnO8 and MgCr2O4 that serve as model systems for Mg-ion battery cathode materials. Magnetic parameters, hyperfine shifts and quadrupolar parameters were calculated ab initio using hybrid DFT and compared to the experimental values obtained from NMR and magnetic measurements. We show that the rotor assisted population transfer (RAPT) pulse sequence can be used to enhance the signal-to-noise ratio in paramagnetic 25Mg spectra without distortions in the spinning sideband manifold. In addition, the value of the predicted quadrupolar coupling constant of Mg6MnO8 was confirmed using the RAPT pulse sequence. We further apply the same methodology to study the NMR spectra of spinel compounds MgV2O4 and MgMn2O4, candidate cathode materials for Mg-ion batteries.",

author = "Jeongjae Lee and Seymour, {Ieuan D.} and Pell, {Andrew J.} and Dutton, {Si{\^a}n E.} and Grey, {Clare P.}",

note = "Funding Information: Via our membership of the UK's HEC Materials Chemistry Consortium, which is funded by EPSRC (EP/L000202), this work used the ARCHER UK National Supercomputing Service (http://www.archer.ac.uk). Research was also carried out at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886. J. L. acknowledges Trinity College Cambridge for the graduate studentship. I. D. S. acknowledges the Geoffrey Moorhouse Gibson Studentship from Trinity College Cambridge. A. J. P. acknowledges the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy under Contract DE-AC02-05CH11231, under the Batteries for Advanced Transportation Technologies (BATT) Program Subcontract 7057154. We thank Dr Derek Middlemiss for helpful discussions and providing a copy of the mean field magnetism code, and Dr Dinu Iuga for helpful advices on DFS experiments. Publisher Copyright: {\textcopyright} the Owner Societies 2017.",

year = "2016",

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doi = "10.1039/c6cp06338a",

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AU - Dutton, Siân E.

AU - Grey, Clare P.

N1 - Funding Information: Via our membership of the UK's HEC Materials Chemistry Consortium, which is funded by EPSRC (EP/L000202), this work used the ARCHER UK National Supercomputing Service (http://www.archer.ac.uk). Research was also carried out at the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886. J. L. acknowledges Trinity College Cambridge for the graduate studentship. I. D. S. acknowledges the Geoffrey Moorhouse Gibson Studentship from Trinity College Cambridge. A. J. P. acknowledges the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy under Contract DE-AC02-05CH11231, under the Batteries for Advanced Transportation Technologies (BATT) Program Subcontract 7057154. We thank Dr Derek Middlemiss for helpful discussions and providing a copy of the mean field magnetism code, and Dr Dinu Iuga for helpful advices on DFS experiments. Publisher Copyright: © the Owner Societies 2017.

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N2 - Rechargeable battery systems based on Mg-ion chemistries are generating significant interest as potential alternatives to Li-ion batteries. Despite the wealth of local structural information that could potentially be gained from Nuclear Magnetic Resonance (NMR) experiments of Mg-ion battery materials, systematic 25Mg solid-state NMR studies have been scarce due to the low natural abundance, low gyromagnetic ratio, and significant quadrupole moment of 25Mg (I = 5/2). This work reports a combined experimental 25Mg NMR and first principles density functional theory (DFT) study of paramagnetic Mg transition metal oxide systems Mg6MnO8 and MgCr2O4 that serve as model systems for Mg-ion battery cathode materials. Magnetic parameters, hyperfine shifts and quadrupolar parameters were calculated ab initio using hybrid DFT and compared to the experimental values obtained from NMR and magnetic measurements. We show that the rotor assisted population transfer (RAPT) pulse sequence can be used to enhance the signal-to-noise ratio in paramagnetic 25Mg spectra without distortions in the spinning sideband manifold. In addition, the value of the predicted quadrupolar coupling constant of Mg6MnO8 was confirmed using the RAPT pulse sequence. We further apply the same methodology to study the NMR spectra of spinel compounds MgV2O4 and MgMn2O4, candidate cathode materials for Mg-ion batteries.

AB - Rechargeable battery systems based on Mg-ion chemistries are generating significant interest as potential alternatives to Li-ion batteries. Despite the wealth of local structural information that could potentially be gained from Nuclear Magnetic Resonance (NMR) experiments of Mg-ion battery materials, systematic 25Mg solid-state NMR studies have been scarce due to the low natural abundance, low gyromagnetic ratio, and significant quadrupole moment of 25Mg (I = 5/2). This work reports a combined experimental 25Mg NMR and first principles density functional theory (DFT) study of paramagnetic Mg transition metal oxide systems Mg6MnO8 and MgCr2O4 that serve as model systems for Mg-ion battery cathode materials. Magnetic parameters, hyperfine shifts and quadrupolar parameters were calculated ab initio using hybrid DFT and compared to the experimental values obtained from NMR and magnetic measurements. We show that the rotor assisted population transfer (RAPT) pulse sequence can be used to enhance the signal-to-noise ratio in paramagnetic 25Mg spectra without distortions in the spinning sideband manifold. In addition, the value of the predicted quadrupolar coupling constant of Mg6MnO8 was confirmed using the RAPT pulse sequence. We further apply the same methodology to study the NMR spectra of spinel compounds MgV2O4 and MgMn2O4, candidate cathode materials for Mg-ion batteries.

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A systematic study of ²⁵Mg NMR in paramagnetic transition metal oxides: Applications to Mg-ion battery materials

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