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<p>Inactive cation doping has demonstrated potential in stabilizing high-capacity ultrahigh-Ni layered oxide cathodes. Yet, maximizing their structural and thermal stability with a limited doping content remains a significant challenge. In this study, we have sought to address this challenge by regulating the distribution of cation dopants in polycrystalline material and designing a surface Nb-dopant-enriched ultrahigh-Ni and Co-free cathode. In situ X-ray diffraction and density functional theory calculation demonstrate that surface Nb-dopant enrichment alleviates the H2/H3 phase transition and reduces the volume shrinkage, making the absence of microcracks in the ultrahigh-Ni cathode. Furthermore, the side reactions occurring at the electrode/electrolyte interface are mitigated, leading to a reduction in electrochemical impedance and the facilitation of stable redox contributions. The designed ultrahigh-Ni cathode shows significantly improved structural stability and obtains an outstanding capacity retention of 97.1% even after 400 cycles, which exceeds the 66.5% capacity retention of the pristine cathode. Moreover, the enhanced thermal stability of the surface Nb-dopant-enriched cathode is evidenced by its higher thermal runaway temperature and lower heat release. This proposed strategy offers a feasible solution for stabilizing ultrahigh-Ni cathodes under a low doping content.</p> Graphical abstract <p></p>

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Enabling structurally and thermally stable ultrahigh-Ni and Co-free oxide cathodes by Nb-dopant-enriched surface

  • 期刊论文

  • 发表日期：

    2025年9月10日

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  • Mao-Sheng Gong,
  • Jia-Cheng Li,
  • Feng Li,
  • Mo-Han Dong,
  • Ze-Zhou Lin,
  • Hong-Zhou Zhang,
  • Xuan-Ming Chang,
  • Pei-Yu Hou,
  • Xi-Jin Xu,
  • Lian-Qi Zhang

摘要

Inactive cation doping has demonstrated potential in stabilizing high-capacity ultrahigh-Ni layered oxide cathodes. Yet, maximizing their structural and thermal stability with a limited doping content remains a significant challenge. In this study, we have sought to address this challenge by regulating the distribution of cation dopants in polycrystalline material and designing a surface Nb-dopant-enriched ultrahigh-Ni and Co-free cathode. In situ X-ray diffraction and density functional theory calculation demonstrate that surface Nb-dopant enrichment alleviates the H2/H3 phase transition and reduces the volume shrinkage, making the absence of microcracks in the ultrahigh-Ni cathode. Furthermore, the side reactions occurring at the electrode/electrolyte interface are mitigated, leading to a reduction in electrochemical impedance and the facilitation of stable redox contributions. The designed ultrahigh-Ni cathode shows significantly improved structural stability and obtains an outstanding capacity retention of 97.1% even after 400 cycles, which exceeds the 66.5% capacity retention of the pristine cathode. Moreover, the enhanced thermal stability of the surface Nb-dopant-enriched cathode is evidenced by its higher thermal runaway temperature and lower heat release. This proposed strategy offers a feasible solution for stabilizing ultrahigh-Ni cathodes under a low doping content.

Graphical abstract