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<p>Pseudocapacitive materials employ rapid, non-diffusion-limited faradaic processes to store charge, demonstrating significant potential for fast-charging batteries and supercapacitors. However, the high redox potentials of existing pseudocapacitive anodes substantially lower the overall cell voltage and energy density. Here, a cation-disordered rock-salt lithium titanium oxyfluoride (DRX-Li<sub>x</sub>TiOF<sub>2</sub>, 0 &lt; x &lt; 2) is reported to reversibly accommodate approximately 1.19&#xa0;mol of Li<sup>+</sup> (~ 310&#xa0;mAh&#xa0;g<sup>−1</sup>) and delivers high-rate performance (exceeding 64.4&#xa0;C) via pseudocapacitive Li<sup>+</sup> storage within a low potential window extending down to 0.1&#xa0;V vs. Li<sup>+</sup>/Li. This pseudocapacitive behavior is characterized by several structural and electrochemical features: the absence of phase transformation during Li<sup>+</sup> intercalation, quasi-rectangular cyclic voltammetry curves, sloping charge/discharge profiles and a surface-controlled current response. We further reveal that the pseudocapacitive characteristics originate from a three-dimensional percolation network that facilitates fast Li<sup>+</sup> migration with low energy barriers, enabled by a cation/anion-disordered structure arising from the mixed occupancy of Li/Ti cations and O/F anions. Owing to its low operating potential and high-rate capability, DRX-Li<sub>x</sub>TiOF<sub>2</sub> allows a lithium-ion capacitor to attain 4.0&#xa0;V cell voltage and achieve energy and power densities several times higher than those obtained with conventional anodes, such as battery-type Li<sub>4</sub>Ti<sub>5</sub>O<sub>12</sub> or pseudocapacitive materials like Nb<sub>2</sub>O<sub>5</sub> and TiO<sub>2</sub>. </p>

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Cation-Disordered Rock-Salt Lithium Titanium Oxyfluoride Anode Enabling High-Rate Li-Ion Storage Through a 3D Percolation Network

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年3月10日

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  • Jing Gao,
  • Minghao Hua,
  • Junze Lu,
  • Yuying Qin,
  • Shuxian Zhang,
  • Qingyu Li,
  • Lidong Yang,
  • Chengxiang Wang,
  • Xiaohang Lin,
  • Yuanwei Sun,
  • Longwei Yin,
  • Rutao Wang

摘要

Pseudocapacitive materials employ rapid, non-diffusion-limited faradaic processes to store charge, demonstrating significant potential for fast-charging batteries and supercapacitors. However, the high redox potentials of existing pseudocapacitive anodes substantially lower the overall cell voltage and energy density. Here, a cation-disordered rock-salt lithium titanium oxyfluoride (DRX-LixTiOF2, 0 < x < 2) is reported to reversibly accommodate approximately 1.19 mol of Li+ (~ 310 mAh g−1) and delivers high-rate performance (exceeding 64.4 C) via pseudocapacitive Li+ storage within a low potential window extending down to 0.1 V vs. Li+/Li. This pseudocapacitive behavior is characterized by several structural and electrochemical features: the absence of phase transformation during Li+ intercalation, quasi-rectangular cyclic voltammetry curves, sloping charge/discharge profiles and a surface-controlled current response. We further reveal that the pseudocapacitive characteristics originate from a three-dimensional percolation network that facilitates fast Li+ migration with low energy barriers, enabled by a cation/anion-disordered structure arising from the mixed occupancy of Li/Ti cations and O/F anions. Owing to its low operating potential and high-rate capability, DRX-LixTiOF2 allows a lithium-ion capacitor to attain 4.0 V cell voltage and achieve energy and power densities several times higher than those obtained with conventional anodes, such as battery-type Li4Ti5O12 or pseudocapacitive materials like Nb2O5 and TiO2.