4.7 v Operation of the Cr4+/Cr3+ Redox Couple in Na3Cr2(PO4)2F3

Kosuke Kawai, Daisuke Asakura, Shin Ichi Nishimura, Atsuo Yamada*

*この研究の対応する著者

研究成果: Article査読

3 被引用数 (Scopus)

抄録

Increasing the energy density of sodium-ion battery systems requires high-voltage cathode materials to compensate for the inherently higher redox potential of the Na/Na+ couple compared to the Li/Li+ couple (difference of 0.3 V). Distinct from the high-voltage (>4.2 V) operation using late transition metals (Co3+/Co2+ or Ni3+/Ni2+) in previously reported polyanionic compounds, here we identify the record-high Cr4+/Cr3+ (3d2/3d3) redox potential in Na3-xCr2(PO4)2F3 (0 < x < 1) at 4.7 V vs Na/Na+. Despite higher d-band position at early 3d transition metal with smaller effective nuclear charge compared to late transition metals, Cr 3d(t2g) in less than half-filled state possesses no energy level increments arising from crystal field splitting and intra-orbital Coulombic penalty, leading to extremely high voltages of the Cr4+/Cr3+ (3d2/3d3) redox couple.

本文言語English
ページ(範囲)1373-1379
ページ数7
ジャーナルChemistry of Materials
33
4
DOI
出版ステータスPublished - 2021 2月 23
外部発表はい

ASJC Scopus subject areas

  • 化学 (全般)
  • 化学工学(全般)
  • 材料化学

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