2024-03-29T08:21:34Z
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2023-01-16T04:12:47Z
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Quantitative analysis of cation mixing and local valence states in LiNixMn2−xO4 using concurrent HARECXS and HARECES measurements
Yamamoto, Yu
68346
Kataoka, Kunimitsu
68347
Akimoto, Junji
68348
Tatsumi, Kazuyoshi
68349
Kousaka, Takashi
68350
Ohnishi, Jun
68351
Takahashi, Teruo
68352
Muto, Shunsuke
68353
lithium ion secondary batteries
positive electrode materials
cation mixing
site-specific EELS
electron channeling
multiple linear regression
Cation mixing in positive electrode materials for rechargeable lithium ion batteries, LiNixMn2−xO4 (x = 0, 0.2, 0.5) and Li0.21Ni0.7Mn1.64O4−δ (denoted as x = 0.7), is analyzed by high-angular-resolution electron-channeling X-ray/electron spectroscopy (HARECXS/HARECES) techniques, using energy-dispersive X-ray spectroscopy and electron energy-loss spectroscopy. Mixing between the tetrahedral lithium sites and the octahedral transition metal sites is quantified, and the site-dependent valence states of the transition metals are examined. In the non-doped (x = 0) sample, Mn was found to occupy only octahedral sites as either Mn3+ or Mn4+. For x = 0.2–0.7, some of the nickel ions (6–13% depending on x) occupy tetrahedral anti-sites. All the nickel ions are in the divalent state, regardless of the occupation site. For x = 0.2 and 0.7, manganese ions occupy both octahedral and tetrahedral sites; those in the octahedral sites are tetravalent, while the tetrahedral sites contain a mixture of divalent and trivalent ions. For x = 0.5, manganese occupies only the octahedral sites, with all ions determined to be in the tetravalent state (within experimental accuracy). All the samples substantially satisfied the local charge neutrality conditions. This study demonstrates the feasibility of using HARECXS/HARECES for quantitative analysis of the atomic configuration and valence states in lithium manganese oxide spinel materials.
journal article
Oxford University Press
2016-06
application/pdf
Microscopy (Tokyo)
3
65
253
262
http://doi.org/10.1093/jmicro/dfw008
http://hdl.handle.net/2237/25265
2050-5698
https://nagoya.repo.nii.ac.jp/record/23075/files/MICROSCOPY_v65_n3_2016_p253-262.pdf
eng
https://doi.org/10.1093/jmicro/dfw008
This is a pre-copyedited, author-produced version of an article accepted for publication in [Microscopy (Tokyo)] following peer review. The version of record [Microscopy (Tokyo). v.65, n.3, 2016, p.253-262] is available online at: http://dx.doi.org/10.1093/jmicro/dfw008