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<p>The rapid advancement of electronic devices has resulted in increasingly demanding performance requirements for high-voltage LiCoO<sub>2</sub> (LCO) cathodes. However, LCO exhibits significant irreversible phase transitions and detrimental side reactions under high voltages. Herein, Mg/Zr co-doped and Li<sub>3</sub>PO<sub>4</sub>-coated LiCoO<sub>2</sub> (denoted as MZP-LCO) was synthesized through an element self-diffusion reaction at a high temperature. Mg<sup>2</sup>⁺ and Zr<sup>4+</sup> can partially replace Li⁺ in the LCO structure, creating a homogeneous concentration distribution with a 60 nm thickness from the surface to the interior. Mg<sup>2</sup>⁺ serves as a stabilizing “pillar” to suppress Co–O layer sliding during deep delithiation, enhancing the structural integrity of LCO, while Zr<sup>4+</sup> expands the Li⁺ deintercalation channels, thereby increasing the capacity. Furthermore, a Li<sub>3</sub>PO<sub>4</sub> nano-coating layer forms<i> in situ</i> on the surface of the LCO, improving Li⁺ transport efficiency and successfully inhibiting harmful side reactions at the electrode surface. The half-cell of MZP-LCO exhibits a capacity of 154.7&#xa0;mAh⋅g<sup>−1</sup> after 200 cycles at 0.5C within 3.0–4.6&#xa0;V, and demonstrates superior rate capability, maintaining a capacity of 156.1&#xa0;mAh⋅g<sup>−1</sup> at 10C. The exceptional electrochemical performance can be attributed to the synergistic effects of the uniform Mg/Zr doping within the LCO and the Li<sub>3</sub>PO<sub>4</sub> coating nanolayer on the surface. These findings offer valuable insights for resolving the issues related to LCO cathode performance degradation at high voltages.</p> Graphical abstract <p></p>

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Bulk-surface dual modification via Mg/Zr doping and Li3PO4 coating for suppressing phase transition and side reaction in 4.6 V LiCoO2

  • 期刊论文

  • 发表日期：

    2025年8月1日

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  • Li-Mei Ma,
  • Yi Liu,
  • Meng-Hui Qiu,
  • Yan-Hong Yin,
  • Xian-Bin Liu,
  • Ting Liu,
  • Ye-Sheng Li

摘要

The rapid advancement of electronic devices has resulted in increasingly demanding performance requirements for high-voltage LiCoO2 (LCO) cathodes. However, LCO exhibits significant irreversible phase transitions and detrimental side reactions under high voltages. Herein, Mg/Zr co-doped and Li3PO4-coated LiCoO2 (denoted as MZP-LCO) was synthesized through an element self-diffusion reaction at a high temperature. Mg2⁺ and Zr4+ can partially replace Li⁺ in the LCO structure, creating a homogeneous concentration distribution with a 60 nm thickness from the surface to the interior. Mg2⁺ serves as a stabilizing “pillar” to suppress Co–O layer sliding during deep delithiation, enhancing the structural integrity of LCO, while Zr4+ expands the Li⁺ deintercalation channels, thereby increasing the capacity. Furthermore, a Li3PO4 nano-coating layer forms in situ on the surface of the LCO, improving Li⁺ transport efficiency and successfully inhibiting harmful side reactions at the electrode surface. The half-cell of MZP-LCO exhibits a capacity of 154.7 mAh⋅g−1 after 200 cycles at 0.5C within 3.0–4.6 V, and demonstrates superior rate capability, maintaining a capacity of 156.1 mAh⋅g−1 at 10C. The exceptional electrochemical performance can be attributed to the synergistic effects of the uniform Mg/Zr doping within the LCO and the Li3PO4 coating nanolayer on the surface. These findings offer valuable insights for resolving the issues related to LCO cathode performance degradation at high voltages.

Graphical abstract