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Nature of the “Z”-phase in layered Na-ion battery cathodes

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Nature of the “Z”-phase in layered Na-ion battery cathodes. / Somerville, James W.; Sobkowiak, Adam; Tapia-Ruiz, Nuria et al.
In: Energy and Environmental Science, Vol. 2019, No. 12, 01.07.2019, p. 2223-2232.

Research output: Contribution to Journal/MagazineJournal articlepeer-review

Harvard

Somerville, JW, Sobkowiak, A, Tapia-Ruiz, N, Billaud, J, Lozano, JG, House, RA, Gallington, LC, Ericsson, T, Haggstrom, L, Roberts, MR, Maitra, U & Bruce, PG 2019, 'Nature of the “Z”-phase in layered Na-ion battery cathodes', Energy and Environmental Science, vol. 2019, no. 12, pp. 2223-2232. https://doi.org/10.1039/C8EE02991A

APA

Somerville, J. W., Sobkowiak, A., Tapia-Ruiz, N., Billaud, J., Lozano, J. G., House, R. A., Gallington, L. C., Ericsson, T., Haggstrom, L., Roberts, M. R., Maitra, U., & Bruce, P. G. (2019). Nature of the “Z”-phase in layered Na-ion battery cathodes. Energy and Environmental Science, 2019(12), 2223-2232. https://doi.org/10.1039/C8EE02991A

Vancouver

Somerville JW, Sobkowiak A, Tapia-Ruiz N, Billaud J, Lozano JG, House RA et al. Nature of the “Z”-phase in layered Na-ion battery cathodes. Energy and Environmental Science. 2019 Jul 1;2019(12):2223-2232. Epub 2019 May 17. doi: 10.1039/C8EE02991A

Author

Somerville, James W. ; Sobkowiak, Adam ; Tapia-Ruiz, Nuria et al. / Nature of the “Z”-phase in layered Na-ion battery cathodes. In: Energy and Environmental Science. 2019 ; Vol. 2019, No. 12. pp. 2223-2232.

Bibtex

@article{9928ddadc5f2446fb0537faf7ef64338,
title = "Nature of the “Z”-phase in layered Na-ion battery cathodes",
abstract = "Layered sodium transition metal oxides with the P2 structure, e.g. Na2/3[Ni1/3Mn2/3]O2, are regarded as candidates for Na-ion battery cathodes. On charging, extraction of Na destabilizes the P2 phase (ABBA oxide ion stacking) in which Na+ is in trigonal prismatic coordination, resulting in layer gliding and formation of an O2 phase (ABAC stacking) with octahedral coordination. However, many related compounds do not exhibit such a simple P2 to O2 transition but rather form a so called “Z”-phase. Substituting Ni by Fe in Na2/3[Ni1/3Mn2/3]O2 is attractive as it reduces cost. The Fe containing compounds, such as Na2/3[Ni1/6Mn1/2Fe1/3]O2, form a “Z”-phase when charged above 4.1 V vs. Na+/Na. By combining ex situ and operando X-ray diffraction with scanning transmission electron microscopy and simulated diffraction patterns, we demonstrate that the “Z”-phase is most accurately described as a continuously changing intergrowth structure which evolves from P2 to O2 through the OP4 structure as an intermediate. On charging, Na+ removal results in O-type stacking faults within the P2 structure which increase in proportion. At 50% O-type stacking faults, the ordered OP4 phase forms and on further charging more O-type stacking faults are formed progressing towards a pure O2 structure. This gives the superficial appearance of a solid solution. Furthermore, in contrast to some previous studies, we did not detect Fe migration at any state-of-charge using 57Fe-M{\"o}ssbauer spectroscopy. It was, however, found that the Fe-substitution serves to disrupt cation ordering in the material.",
author = "Somerville, {James W.} and Adam Sobkowiak and Nuria Tapia-Ruiz and Juliette Billaud and Lozano, {Juan G.} and House, {Rob A} and Gallington, {Leighanne C.} and Tore Ericsson and Lennart Haggstrom and Roberts, {Matthew R.} and Urmimala Maitra and Bruce, {Peter G.}",
year = "2019",
month = jul,
day = "1",
doi = "10.1039/C8EE02991A",
language = "English",
volume = "2019",
pages = "2223--2232",
journal = "Energy and Environmental Science",
issn = "1754-5692",
publisher = "The Royal Society of Chemistry",
number = "12",

}

RIS

TY - JOUR

T1 - Nature of the “Z”-phase in layered Na-ion battery cathodes

AU - Somerville, James W.

AU - Sobkowiak, Adam

AU - Tapia-Ruiz, Nuria

AU - Billaud, Juliette

AU - Lozano, Juan G.

AU - House, Rob A

AU - Gallington, Leighanne C.

AU - Ericsson, Tore

AU - Haggstrom, Lennart

AU - Roberts, Matthew R.

AU - Maitra, Urmimala

AU - Bruce, Peter G.

PY - 2019/7/1

Y1 - 2019/7/1

N2 - Layered sodium transition metal oxides with the P2 structure, e.g. Na2/3[Ni1/3Mn2/3]O2, are regarded as candidates for Na-ion battery cathodes. On charging, extraction of Na destabilizes the P2 phase (ABBA oxide ion stacking) in which Na+ is in trigonal prismatic coordination, resulting in layer gliding and formation of an O2 phase (ABAC stacking) with octahedral coordination. However, many related compounds do not exhibit such a simple P2 to O2 transition but rather form a so called “Z”-phase. Substituting Ni by Fe in Na2/3[Ni1/3Mn2/3]O2 is attractive as it reduces cost. The Fe containing compounds, such as Na2/3[Ni1/6Mn1/2Fe1/3]O2, form a “Z”-phase when charged above 4.1 V vs. Na+/Na. By combining ex situ and operando X-ray diffraction with scanning transmission electron microscopy and simulated diffraction patterns, we demonstrate that the “Z”-phase is most accurately described as a continuously changing intergrowth structure which evolves from P2 to O2 through the OP4 structure as an intermediate. On charging, Na+ removal results in O-type stacking faults within the P2 structure which increase in proportion. At 50% O-type stacking faults, the ordered OP4 phase forms and on further charging more O-type stacking faults are formed progressing towards a pure O2 structure. This gives the superficial appearance of a solid solution. Furthermore, in contrast to some previous studies, we did not detect Fe migration at any state-of-charge using 57Fe-Mössbauer spectroscopy. It was, however, found that the Fe-substitution serves to disrupt cation ordering in the material.

AB - Layered sodium transition metal oxides with the P2 structure, e.g. Na2/3[Ni1/3Mn2/3]O2, are regarded as candidates for Na-ion battery cathodes. On charging, extraction of Na destabilizes the P2 phase (ABBA oxide ion stacking) in which Na+ is in trigonal prismatic coordination, resulting in layer gliding and formation of an O2 phase (ABAC stacking) with octahedral coordination. However, many related compounds do not exhibit such a simple P2 to O2 transition but rather form a so called “Z”-phase. Substituting Ni by Fe in Na2/3[Ni1/3Mn2/3]O2 is attractive as it reduces cost. The Fe containing compounds, such as Na2/3[Ni1/6Mn1/2Fe1/3]O2, form a “Z”-phase when charged above 4.1 V vs. Na+/Na. By combining ex situ and operando X-ray diffraction with scanning transmission electron microscopy and simulated diffraction patterns, we demonstrate that the “Z”-phase is most accurately described as a continuously changing intergrowth structure which evolves from P2 to O2 through the OP4 structure as an intermediate. On charging, Na+ removal results in O-type stacking faults within the P2 structure which increase in proportion. At 50% O-type stacking faults, the ordered OP4 phase forms and on further charging more O-type stacking faults are formed progressing towards a pure O2 structure. This gives the superficial appearance of a solid solution. Furthermore, in contrast to some previous studies, we did not detect Fe migration at any state-of-charge using 57Fe-Mössbauer spectroscopy. It was, however, found that the Fe-substitution serves to disrupt cation ordering in the material.

U2 - 10.1039/C8EE02991A

DO - 10.1039/C8EE02991A

M3 - Journal article

VL - 2019

SP - 2223

EP - 2232

JO - Energy and Environmental Science

JF - Energy and Environmental Science

SN - 1754-5692

IS - 12

ER -