<p>TiNb<sub>2</sub>O<sub>7</sub> represents an up-and-coming anode material for fast-charging lithium-ion batteries, but its practicalities are severely impeded by slow transfer rates of ionic and electronic especially at the low-temperature conditions. Herein, we introduce crystallographic engineering to enhance structure stability and promote Li<sup>+</sup> diffusion kinetics of TiNb<sub>2</sub>O<sub>7</sub> (TNO). The density functional theory computation reveals that Ti<sup>4+</sup> is replaced by Sb<sup>5+</sup> and Nb<sup>5+</sup> in crystal lattices, which can reduce the Li<sup>+</sup> diffusion impediment and improve electronic conductivity. Synchrotron radiation X-ray 3D nano-computed tomography and in situ X-ray diffraction measurement confirm the introduction of Sb/Nb alleviates volume expansion during lithiation and delithiation processes, contributing to enhancing structure stability. Extended X-ray absorption fine structure spectra results verify that crystallographic engineering also increases short Nb-O bond length in TNO-Sb/Nb. Accordingly, the TNO-Sb/Nb anode delivers an outstanding capacity retention rate of 89.8% at 10 C after 700 cycles and excellent rate performance (140.4 mAh g<sup>−1</sup> at 20 C). Even at −30&#xa0;°C, TNO-Sb/Nb anode delivers a capacity of 102.6 mAh g<sup>−1</sup> with little capacity degeneration for 500 cycles. This work provides guidance for the design of fast-charging batteries at low-temperature condition.</p>

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Crystallographic Engineering Enables Fast Low-Temperature Ion Transport of TiNb2O7 for Cold-Region Lithium-Ion Batteries

  • Lihua Wei,
  • Shenglu Geng,
  • Hailu Liu,
  • Liang Deng,
  • Yiyang Mao,
  • Yanbin Ning,
  • Biqiong Wang,
  • Yueping Xiong,
  • Yan Zhang,
  • Shuaifeng Lou

摘要

TiNb2O7 represents an up-and-coming anode material for fast-charging lithium-ion batteries, but its practicalities are severely impeded by slow transfer rates of ionic and electronic especially at the low-temperature conditions. Herein, we introduce crystallographic engineering to enhance structure stability and promote Li+ diffusion kinetics of TiNb2O7 (TNO). The density functional theory computation reveals that Ti4+ is replaced by Sb5+ and Nb5+ in crystal lattices, which can reduce the Li+ diffusion impediment and improve electronic conductivity. Synchrotron radiation X-ray 3D nano-computed tomography and in situ X-ray diffraction measurement confirm the introduction of Sb/Nb alleviates volume expansion during lithiation and delithiation processes, contributing to enhancing structure stability. Extended X-ray absorption fine structure spectra results verify that crystallographic engineering also increases short Nb-O bond length in TNO-Sb/Nb. Accordingly, the TNO-Sb/Nb anode delivers an outstanding capacity retention rate of 89.8% at 10 C after 700 cycles and excellent rate performance (140.4 mAh g−1 at 20 C). Even at −30 °C, TNO-Sb/Nb anode delivers a capacity of 102.6 mAh g−1 with little capacity degeneration for 500 cycles. This work provides guidance for the design of fast-charging batteries at low-temperature condition.