Structural origins of voltage mysteresis in the Na-Ion cathode P2-Na0.67[Mg0.28Mn0.72]O2: A combined spectroscopic and density functional theory study

Euan N. Bassey; Philip J. Reeves; Michael A. Jones; Jeongjae Lee; Ieuan D. Seymour; Giannantonio Cibin; Clare P. Grey

doi:10.1021/acs.chemmater.1c00248

Structural origins of voltage mysteresis in the Na-Ion cathode P2-Na_0.67[Mg_0.28Mn_0.72]O₂: A combined spectroscopic and density functional theory study

Euan N. Bassey, Philip J. Reeves, Michael A. Jones, Jeongjae Lee, Ieuan D. Seymour, Giannantonio Cibin, Clare P. Grey^*

^*Corresponding author for this work

Chemistry

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

24 Citations (Scopus)

Abstract

P2-layered sodium-ion battery (NIB) cathodes are a promising class of Na-ion electrode materials with high Na+ mobility and relatively high capacities. In this work, we report the structural changes that take place in P2-Na0.67[Mg0.28Mn0.72]O2. Using ex situ X-ray diffraction, Mn K-edge extended X-ray absorption fine structure, and 23Na NMR spectroscopy, we identify the bulk phase changes along the first electrochemical charge-discharge cycle - including the formation of a high-voltage "Z phase", an intergrowth of the OP4 and O2 phases. Our ab initio transition state searches reveal that reversible Mg2+ migration in the Z phase is both kinetically and thermodynamically favorable at high voltages. We propose that Mg2+ migration is a significant contributor to the observed voltage hysteresis in Na0.67[Mg0.28Mn0.72]O2 and identify qualitative changes in the Na+ ion mobility.

Original language	English
Pages (from-to)	4890-4906
Number of pages	17
Journal	Chemistry of Materials
Volume	33
Issue number	13
Early online date	21 Jun 2021
DOIs	https://doi.org/10.1021/acs.chemmater.1c00248
Publication status	Published - 13 Jul 2021

Bibliographical note

Funding Information:
E.N.B. acknowledges funding from the Engineering Physical Sciences Research Council (EPSRC) via the National Productivity Interest Fund (NPIF) 2018 and is also grateful for use of the ARCHER UK National Supercomputing Service via our membership in the UK’s HEC Materials Chemistry Consortium, funded by the EPSRC (EP/L000202). Research was also carried out at the Center for Functional Nanomaterials, Brookhaven National Laboratory, through the U.S. Department of Energy, Office of Basic Energy Sciences, Contract DE-AC02-98CH10866. P.J.R. thanks the Northeast Centre for Chemical Energy Storage (NECCES), an Energy Frontier Research Centre funded by the US Department of Energy, Office of Basic Energy Sciences, award DE-SC0012583. M.A.J. is grateful for the financial support of the EPSRC Centre for Doctoral Training (CDT) in Nanoscience and Nanotechnology Award EP/L015978/1. J.L. was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (no. 2019R1A6A1A10073437). E.N.B. also wishes to thank Dr M.F. Groh for assistance with setting up capillary XRD measurements.

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Bassey_etal_CM_Structural_Origins_Of_VORFinal published version, 2.57 MBLicence: CC BY

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title = "Structural origins of voltage mysteresis in the Na-Ion cathode P2-Na0.67[Mg0.28Mn0.72]O2: A combined spectroscopic and density functional theory study",

abstract = "P2-layered sodium-ion battery (NIB) cathodes are a promising class of Na-ion electrode materials with high Na+ mobility and relatively high capacities. In this work, we report the structural changes that take place in P2-Na0.67[Mg0.28Mn0.72]O2. Using ex situ X-ray diffraction, Mn K-edge extended X-ray absorption fine structure, and 23Na NMR spectroscopy, we identify the bulk phase changes along the first electrochemical charge-discharge cycle - including the formation of a high-voltage {"}Z phase{"}, an intergrowth of the OP4 and O2 phases. Our ab initio transition state searches reveal that reversible Mg2+ migration in the Z phase is both kinetically and thermodynamically favorable at high voltages. We propose that Mg2+ migration is a significant contributor to the observed voltage hysteresis in Na0.67[Mg0.28Mn0.72]O2 and identify qualitative changes in the Na+ ion mobility.",

author = "Bassey, {Euan N.} and Reeves, {Philip J.} and Jones, {Michael A.} and Jeongjae Lee and Seymour, {Ieuan D.} and Giannantonio Cibin and Grey, {Clare P.}",

note = "Funding Information: E.N.B. acknowledges funding from the Engineering Physical Sciences Research Council (EPSRC) via the National Productivity Interest Fund (NPIF) 2018 and is also grateful for use of the ARCHER UK National Supercomputing Service via our membership in the UK{\textquoteright}s HEC Materials Chemistry Consortium, funded by the EPSRC (EP/L000202). Research was also carried out at the Center for Functional Nanomaterials, Brookhaven National Laboratory, through the U.S. Department of Energy, Office of Basic Energy Sciences, Contract DE-AC02-98CH10866. P.J.R. thanks the Northeast Centre for Chemical Energy Storage (NECCES), an Energy Frontier Research Centre funded by the US Department of Energy, Office of Basic Energy Sciences, award DE-SC0012583. M.A.J. is grateful for the financial support of the EPSRC Centre for Doctoral Training (CDT) in Nanoscience and Nanotechnology Award EP/L015978/1. J.L. was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (no. 2019R1A6A1A10073437). E.N.B. also wishes to thank Dr M.F. Groh for assistance with setting up capillary XRD measurements. Publisher Copyright: {\textcopyright} ",

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month = jul,

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doi = "10.1021/acs.chemmater.1c00248",

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AU - Bassey, Euan N.

AU - Reeves, Philip J.

AU - Jones, Michael A.

AU - Lee, Jeongjae

AU - Seymour, Ieuan D.

AU - Cibin, Giannantonio

AU - Grey, Clare P.

N1 - Funding Information: E.N.B. acknowledges funding from the Engineering Physical Sciences Research Council (EPSRC) via the National Productivity Interest Fund (NPIF) 2018 and is also grateful for use of the ARCHER UK National Supercomputing Service via our membership in the UK’s HEC Materials Chemistry Consortium, funded by the EPSRC (EP/L000202). Research was also carried out at the Center for Functional Nanomaterials, Brookhaven National Laboratory, through the U.S. Department of Energy, Office of Basic Energy Sciences, Contract DE-AC02-98CH10866. P.J.R. thanks the Northeast Centre for Chemical Energy Storage (NECCES), an Energy Frontier Research Centre funded by the US Department of Energy, Office of Basic Energy Sciences, award DE-SC0012583. M.A.J. is grateful for the financial support of the EPSRC Centre for Doctoral Training (CDT) in Nanoscience and Nanotechnology Award EP/L015978/1. J.L. was supported by the National Research Foundation of Korea (NRF) grant funded by the Korean government (MEST) (no. 2019R1A6A1A10073437). E.N.B. also wishes to thank Dr M.F. Groh for assistance with setting up capillary XRD measurements. Publisher Copyright: ©

PY - 2021/7/13

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N2 - P2-layered sodium-ion battery (NIB) cathodes are a promising class of Na-ion electrode materials with high Na+ mobility and relatively high capacities. In this work, we report the structural changes that take place in P2-Na0.67[Mg0.28Mn0.72]O2. Using ex situ X-ray diffraction, Mn K-edge extended X-ray absorption fine structure, and 23Na NMR spectroscopy, we identify the bulk phase changes along the first electrochemical charge-discharge cycle - including the formation of a high-voltage "Z phase", an intergrowth of the OP4 and O2 phases. Our ab initio transition state searches reveal that reversible Mg2+ migration in the Z phase is both kinetically and thermodynamically favorable at high voltages. We propose that Mg2+ migration is a significant contributor to the observed voltage hysteresis in Na0.67[Mg0.28Mn0.72]O2 and identify qualitative changes in the Na+ ion mobility.

AB - P2-layered sodium-ion battery (NIB) cathodes are a promising class of Na-ion electrode materials with high Na+ mobility and relatively high capacities. In this work, we report the structural changes that take place in P2-Na0.67[Mg0.28Mn0.72]O2. Using ex situ X-ray diffraction, Mn K-edge extended X-ray absorption fine structure, and 23Na NMR spectroscopy, we identify the bulk phase changes along the first electrochemical charge-discharge cycle - including the formation of a high-voltage "Z phase", an intergrowth of the OP4 and O2 phases. Our ab initio transition state searches reveal that reversible Mg2+ migration in the Z phase is both kinetically and thermodynamically favorable at high voltages. We propose that Mg2+ migration is a significant contributor to the observed voltage hysteresis in Na0.67[Mg0.28Mn0.72]O2 and identify qualitative changes in the Na+ ion mobility.

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ER -

Structural origins of voltage mysteresis in the Na-Ion cathode P2-Na_0.67[Mg_0.28Mn_0.72]O₂: A combined spectroscopic and density functional theory study

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