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<p>Increasing the operating voltage can significantly increase the energy density of LiCoO<sub>2</sub>, but it is accompanied by severe structural damage and interface degradation. Especially at a high voltage above 4.5&#xa0;V, LiCoO<sub>2</sub> faces severe challenges, such as irreversible phase transition, lattice oxygen loss, and electrode–electrolyte interface evolution. Herein, a high-voltage LiCoO<sub>2</sub> cathode material with bulk doping and surface coating synergistic modification was designed and prepared. The doped Mg<sup>2+</sup> ions entered the lithium layers as pillars, stabilizing the layered framework. Meanwhile, Li<sub>1.3</sub>La<sub>0.3</sub>Ti<sub>1.7</sub>(PO<sub>4</sub>)<sub>3</sub> was uniformly coated on the surface of LiCoO<sub>2</sub>, which is beneficial for suppressing Co<sup>3+/2+</sup> ion leaching and interface side reactions during cycling. Furthermore, Li<sub>1.3</sub>La<sub>0.3</sub>Ti<sub>1.7</sub>(PO<sub>4</sub>)<sub>3</sub> is a fast ion conductor, which facilitates the rapid transport of lithium ions on the surface of the cathode material. Owing to the synergistic effect of Mg<sup>2+</sup> ion doping and Li<sub>1.3</sub>La<sub>0.3</sub>Ti<sub>1.7</sub>(PO<sub>4</sub>)<sub>3</sub> coating, the orbitals of Co 3d and O 2p in LiCoO<sub>2</sub> crystal are changed, and the irreversible phase transition and oxygen loss are inhibited. The modified material exhibited an excellent electrochemical performance. A discharge capacity of 175.5 mAh·g<sup>−1</sup> at 10 C rate, as well as a capacity retention of 90.14% after 200 cycles at 1 C rate, was achieved in the modified material. This work supplies a new method for developing high-voltage oxide cathodes through bulk and interfacial modification.</p>

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Optimizing the electrochemical performance of LiCoO2 at 4.5 V via synergistic modification of Mg2+ ion doping and Li1.3La0.3Ti1.7(PO4)3 coating

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  • 出版模式：

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  • 发表日期：

    2025年7月1日

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  • Gaoqiang Mao,
  • Jingfan Lu,
  • Haiyan Cai,
  • Wanjing Yu,
  • Hui Tong,
  • Xueyi Guo,
  • Leiying Zeng,
  • Long Jiang

摘要

Increasing the operating voltage can significantly increase the energy density of LiCoO2, but it is accompanied by severe structural damage and interface degradation. Especially at a high voltage above 4.5 V, LiCoO2 faces severe challenges, such as irreversible phase transition, lattice oxygen loss, and electrode–electrolyte interface evolution. Herein, a high-voltage LiCoO2 cathode material with bulk doping and surface coating synergistic modification was designed and prepared. The doped Mg2+ ions entered the lithium layers as pillars, stabilizing the layered framework. Meanwhile, Li1.3La0.3Ti1.7(PO4)3 was uniformly coated on the surface of LiCoO2, which is beneficial for suppressing Co3+/2+ ion leaching and interface side reactions during cycling. Furthermore, Li1.3La0.3Ti1.7(PO4)3 is a fast ion conductor, which facilitates the rapid transport of lithium ions on the surface of the cathode material. Owing to the synergistic effect of Mg2+ ion doping and Li1.3La0.3Ti1.7(PO4)3 coating, the orbitals of Co 3d and O 2p in LiCoO2 crystal are changed, and the irreversible phase transition and oxygen loss are inhibited. The modified material exhibited an excellent electrochemical performance. A discharge capacity of 175.5 mAh·g−1 at 10 C rate, as well as a capacity retention of 90.14% after 200 cycles at 1 C rate, was achieved in the modified material. This work supplies a new method for developing high-voltage oxide cathodes through bulk and interfacial modification.