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<p>Lithium-rich layer oxides are expected to be high-capacity cathodes for next-generation lithium-ion batteries, but their performance is hindered by irreversible anionic redox, leading to voltage decay, lag, and slow kinetics. In order to solve these problems, we regulate the Ni/Mn spin state in Li<sub>1.2</sub>Mn<sub>0.6</sub>Ni<sub>0.2</sub>O<sub>2</sub> by Be doping, which generates the superexchange interaction and activates Ni-t<sub>2g</sub> orbitals. The activation of Ni-t<sub>2g</sub> orbitals triggers the reductive coupling mechanism between Ni/O, which improves the reversibility and kinetics of anionic redox. The strong π-type Ni-t<sub>2g</sub>/O-2<i>p</i> interaction forms a stable Ni-(O–O) configuration, suppressing excessive anion oxidation. In this work, the Be modified cathodes have good cycle stability, 0.04 mAh/g and 0.5 mV decay per cycle over 400 cycles at 1 C (60 min, 250 mA g<sup>−1</sup>), with a rate performance of 187 mAh/g at 10 C (6 min, 2500 mA g<sup>−1</sup>), providing a strategy for stabilising oxygen redox chemistry and designing high performance lithium-rich cathodes.</p>

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Superexchange interaction regulates Ni/Mn spin states triggering Ni-t2g/O-2p reductive coupling enabling stable lithium-rich cathode

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年4月25日

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  • Chaoliang Zheng,
  • Yaqing Wang,
  • Huican Mao,
  • Juan Zhang,
  • Xiaoxu Yang,
  • Jie Li,
  • Di Zhang,
  • Xindong Wang,
  • Feiyu Kang,
  • Jianling Li

摘要

Lithium-rich layer oxides are expected to be high-capacity cathodes for next-generation lithium-ion batteries, but their performance is hindered by irreversible anionic redox, leading to voltage decay, lag, and slow kinetics. In order to solve these problems, we regulate the Ni/Mn spin state in Li1.2Mn0.6Ni0.2O2 by Be doping, which generates the superexchange interaction and activates Ni-t2g orbitals. The activation of Ni-t2g orbitals triggers the reductive coupling mechanism between Ni/O, which improves the reversibility and kinetics of anionic redox. The strong π-type Ni-t2g/O-2p interaction forms a stable Ni-(O–O) configuration, suppressing excessive anion oxidation. In this work, the Be modified cathodes have good cycle stability, 0.04 mAh/g and 0.5 mV decay per cycle over 400 cycles at 1 C (60 min, 250 mA g−1), with a rate performance of 187 mAh/g at 10 C (6 min, 2500 mA g−1), providing a strategy for stabilising oxygen redox chemistry and designing high performance lithium-rich cathodes.