Phase boundary structure of LixFePO4 cathode material revealed by atomic-resolution scanning transmission electron microscopy

Akiho Nakamura, Sho Furutsuki, Shin Ichi Nishimura, Tetsuya Tohei, Yukio Sato, Naoya Shibata, Atsuo Yamada, Yuichi Ikuhara

研究成果: ジャーナルへの寄稿記事

17 引用 (Scopus)

抄録

A variety of cathode materials in lithium ion batteries exhibit phase separations during electrochemical reactions, where two phases with different Li compositions are in equilibrium across the phase interface. Because of the lattice mismatch between these phases, large structural distortions are introduced around the interface region. To characterize their potential effect upon the Li migration behavior, the phase interface structure should be determined accurately. In this study, we perform sophisticated structural analyses for phase interfaces in the well-known cathode material LixFePO4, using atomic resolution scanning transmission electron microscopy. The lattice deformation behavior and Li composition gradient are separately measured across the interface and superimposed after spatial calibrations. The combined result reveals that their relationship significantly deviates from simple models, such as Vegard's law or other higher order interpolations. Notably, the interface region has small lattice sizes comparable to the FePO4 phase, while having intermediate Li compositions. The origin of observed structure is discussed considering the local phase stability by estimating the pair distance variations of dominant attractive/repulsive ionic couples. Because of the nonlinear variations of each structural parameter, well-optimized experiments with high spatial resolutions and sufficient accuracies are required to correctly understand the phase interface structures.

元の言語英語
ページ(範囲)6178-6184
ページ数7
ジャーナルChemistry of Materials
26
発行部数21
DOI
出版物ステータス出版済み - 11 11 2014

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Phase interfaces
Phase boundaries
Cathodes
Transmission electron microscopy
Scanning electron microscopy
Chemical analysis
Lattice mismatch
Phase stability
Phase separation
Interpolation
Calibration
Experiments

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

これを引用

Phase boundary structure of LixFePO4 cathode material revealed by atomic-resolution scanning transmission electron microscopy. / Nakamura, Akiho; Furutsuki, Sho; Nishimura, Shin Ichi; Tohei, Tetsuya; Sato, Yukio; Shibata, Naoya; Yamada, Atsuo; Ikuhara, Yuichi.

:: Chemistry of Materials, 巻 26, 番号 21, 11.11.2014, p. 6178-6184.

研究成果: ジャーナルへの寄稿記事

Nakamura, A, Furutsuki, S, Nishimura, SI, Tohei, T, Sato, Y, Shibata, N, Yamada, A & Ikuhara, Y 2014, 'Phase boundary structure of LixFePO4 cathode material revealed by atomic-resolution scanning transmission electron microscopy', Chemistry of Materials, 巻. 26, 番号 21, pp. 6178-6184. https://doi.org/10.1021/cm5024986
Nakamura, Akiho ; Furutsuki, Sho ; Nishimura, Shin Ichi ; Tohei, Tetsuya ; Sato, Yukio ; Shibata, Naoya ; Yamada, Atsuo ; Ikuhara, Yuichi. / Phase boundary structure of LixFePO4 cathode material revealed by atomic-resolution scanning transmission electron microscopy. :: Chemistry of Materials. 2014 ; 巻 26, 番号 21. pp. 6178-6184.
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abstract = "A variety of cathode materials in lithium ion batteries exhibit phase separations during electrochemical reactions, where two phases with different Li compositions are in equilibrium across the phase interface. Because of the lattice mismatch between these phases, large structural distortions are introduced around the interface region. To characterize their potential effect upon the Li migration behavior, the phase interface structure should be determined accurately. In this study, we perform sophisticated structural analyses for phase interfaces in the well-known cathode material LixFePO4, using atomic resolution scanning transmission electron microscopy. The lattice deformation behavior and Li composition gradient are separately measured across the interface and superimposed after spatial calibrations. The combined result reveals that their relationship significantly deviates from simple models, such as Vegard's law or other higher order interpolations. Notably, the interface region has small lattice sizes comparable to the FePO4 phase, while having intermediate Li compositions. The origin of observed structure is discussed considering the local phase stability by estimating the pair distance variations of dominant attractive/repulsive ionic couples. Because of the nonlinear variations of each structural parameter, well-optimized experiments with high spatial resolutions and sufficient accuracies are required to correctly understand the phase interface structures.",
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AU - Sato, Yukio

AU - Shibata, Naoya

AU - Yamada, Atsuo

AU - Ikuhara, Yuichi

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