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DOI	10.1039/c8ee02991a
	Nature of the "z"-phase in layered Na-ion battery cathodes
	Somerville J.W.; Sobkowiak A.; Tapia-Ruiz N.; Billaud J.; Lozano J.G.; House R.A.; Gallington L.C.; Ericsson T.; Häggström L.; Roberts M.R.; Maitra U.; Bruce P.G.
发表日期	2019
ISSN	1754-5692
起始页码	2223
结束页码	2232
卷号	12 期号:7
英文摘要	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. © The Royal Society of Chemistry 2019.
语种	英语
scopus关键词	Cathodes; Charging (batteries); High resolution transmission electron microscopy; Ions; Iron compounds; Scanning electron microscopy; Sodium-ion batteries; Stacking faults; Transition metal oxides; Transition metals; Intergrowth structure; Na-ion batteries; Octahedral coordination; Prismatic coordination; Related compounds; Scanning transmission electron microscopy; Ssbauer spectroscopies; State of charge; Sodium compounds; chemical compound; diffraction; electrode; electron microscopy; fuel cell; transition element
来源期刊	Energy and Environmental Science
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/162768
作者单位	Dept. of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom; Paul Scherrer Institut, Electrochemical Laboratory, Villigen PSI, CH-5232, Switzerland; X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, United States; Dept. of Chemistry, Ångstrom Lab., Uppsala University, Box 538, Uppsala, SE-751 21, Sweden; Faraday Institution, Harwell Campus, Quad One, Becquerel Avenue, Didcot, OX11 0RA, United Kingdom; Etteplan Sweden AB, Solna, SE-171 54, Sweden; Dept. of Chemistry, University of Lancaster, Lancaster, United Kingdom; Dept. de Ingenieria y Ciencia de Los Materiales y Del Transporte, Universidad de Sevilla (EPS-US), Sevilla, Spain; Inst. of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, Giessen, 35392, Germany
推荐引用方式 GB/T 7714	Somerville J.W.,Sobkowiak A.,Tapia-Ruiz N.,et al. Nature of the "z"-phase in layered Na-ion battery cathodes[J],2019,12(7).
APA	Somerville J.W..,Sobkowiak A..,Tapia-Ruiz N..,Billaud J..,Lozano J.G..,...&Bruce P.G..(2019).Nature of the "z"-phase in layered Na-ion battery cathodes.Energy and Environmental Science,12(7).
MLA	Somerville J.W.,et al."Nature of the "z"-phase in layered Na-ion battery cathodes".Energy and Environmental Science 12.7(2019).