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<p>Utilization of ultrahigh-nickel LiNi<sub><i>x</i></sub>Co<sub><i>y</i></sub>Mn<sub>1−<i>x</i>−<i>y</i></sub>O<sub>2</sub> (NCM) (<i>x</i> &gt; 0.97) in Li-ion battery can distinctively boost its energy density through enhancing the discharge capacity of the cathode. However, the deterioration of capacity and thermal stability of the ultrahigh-nickel NCM becomes more serious with approaching Ni content to limit. Here, we proposed a facile and effective strategy by introducing high-valence tungsten (W) into ultrahigh-nickel polycrystalline LiNi<sub>0.98</sub>-Co<sub>0.01</sub>Mn<sub>0.01</sub>O<sub>2</sub> (PCNCM98). The microstructure of W-doped PCNCM98 (W-PCNCM98) primary particle is well-refined and compactly stacked; however, the PCNCM98 is equiaxial and non-uniform with much larger primary particle size. The refined W-PCNCM98 shows enhanced mechanical strength compared with PCNCM98. The average particle hardness of W-PCNCM98 is 104 MPa, which is 1.5 times higher than that of the PCNCM98 (68 MPa). The enhanced mechanical property of W-PCNCM98 effectively suppresses the lattice volume changes and relieves the formation of microcracks resulting from the drastic lattice volume expansion/contraction, which corresponds to the H2–H3 phase transition. Thereafter, the cycling performance of W-PCNCM98 in a pouch-type full cell is significantly enhanced with capacity retention of 73% after 2000 cycles at 1 C at 25 °C, which is 54% higher than that of the PCNCM98. In addition, the enhanced structural stability and strong electron affinity of W<sup>6+</sup> also lead to the enhancement of the thermal stability of W-PCNCM98. The exothermic peak for the W-PCNCM98 cathode was postponed to 203 °C accompanied by a heat generation of 1287 J g<sup>−1</sup>, while for the PCNCM98 it is 190 °C (1528 J g<sup>−1</sup>). This high-valent element, such as tungsten, doping strategy sheds light on the importance of stabilizing the structure of ultrahigh-nickel NCM cathode materials that could accelerate its large-scale applications in electric vehicle market.</p>

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Promoting cycling and thermal stability of ultrahigh-nickel oxide cathodes with well-controlled microstructure and stiffness

  • 期刊论文

  • 发表日期：

    2026年5月14日

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  • Xiaozhen Zhang,
  • Shanshan Bi,
  • Jiande Lin,
  • Yang Ding,
  • Lufeng Yang,
  • Junye Yang,
  • Jianming Zheng,
  • Ying Lin,
  • Xunxin Chen,
  • Zhifeng He,
  • Haitang Zhang,
  • Ang Fu,
  • Yixiao Li,
  • Yong Cheng,
  • Mingzeng Luo,
  • Chuanjing Xu,
  • Yaxin Huang,
  • Deyin Wu,
  • Pengfei Yan,
  • Yu Qiao,
  • Ming-Sheng Wang,
  • Kazumasa Takeshi,
  • Yuli Li,
  • Haipeng Guo,
  • Yan Zhou,
  • Li Wang,
  • Jie Chen,
  • Yong Yang

摘要

Utilization of ultrahigh-nickel LiNixCoyMn1−x−yO2 (NCM) (x > 0.97) in Li-ion battery can distinctively boost its energy density through enhancing the discharge capacity of the cathode. However, the deterioration of capacity and thermal stability of the ultrahigh-nickel NCM becomes more serious with approaching Ni content to limit. Here, we proposed a facile and effective strategy by introducing high-valence tungsten (W) into ultrahigh-nickel polycrystalline LiNi0.98-Co0.01Mn0.01O2 (PCNCM98). The microstructure of W-doped PCNCM98 (W-PCNCM98) primary particle is well-refined and compactly stacked; however, the PCNCM98 is equiaxial and non-uniform with much larger primary particle size. The refined W-PCNCM98 shows enhanced mechanical strength compared with PCNCM98. The average particle hardness of W-PCNCM98 is 104 MPa, which is 1.5 times higher than that of the PCNCM98 (68 MPa). The enhanced mechanical property of W-PCNCM98 effectively suppresses the lattice volume changes and relieves the formation of microcracks resulting from the drastic lattice volume expansion/contraction, which corresponds to the H2–H3 phase transition. Thereafter, the cycling performance of W-PCNCM98 in a pouch-type full cell is significantly enhanced with capacity retention of 73% after 2000 cycles at 1 C at 25 °C, which is 54% higher than that of the PCNCM98. In addition, the enhanced structural stability and strong electron affinity of W6+ also lead to the enhancement of the thermal stability of W-PCNCM98. The exothermic peak for the W-PCNCM98 cathode was postponed to 203 °C accompanied by a heat generation of 1287 J g−1, while for the PCNCM98 it is 190 °C (1528 J g−1). This high-valent element, such as tungsten, doping strategy sheds light on the importance of stabilizing the structure of ultrahigh-nickel NCM cathode materials that could accelerate its large-scale applications in electric vehicle market.