Oxygen Vacancy Enhanced Two-Dimensional Lithium Titanate for Ultrafast and Long-Life Bifunctional Lithium Storage,ACS Applied Materials & Interfaces

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Oxygen Vacancy Enhanced Two-Dimensional Lithium Titanate for Ultrafast and Long-Life Bifunctional Lithium Storage
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2021-04-19 , DOI: 10.1021/acsami.1c02962
Zhenjie Liu ₁ , Yudai Huang ₁ , Yanjun Cai ₂ , Xingchao Wang ₁ , Yue Zhang ₁ , Yong Guo ₁ , Juan Ding ₁ , Wenhua Cheng ₁

Affiliation

Boosting sufficient Li⁺ ion mobility in Li₄Ti₅O₁₂ (LTO) is crucial for high-rate performance lithium storage. Here, an ultrafast charge storage oxygen vacancy two-dimensional (2D) LTO nanosheet was successfully fabricated through a one-pot hydrothermal method. The selectively doped Al³⁺ into octahedron Li⁺/Ti⁴⁺ 16d sites not only provide bulk oxygen vacancy and appropriate distorted TiO₆ octahedra to facilitate Li⁺ ions diffusion, but also serve as a “pillar” to stabilize the Ti–O framework. The oxygen vacancy lowers Li⁺ ion diffusion energy barrier. Moreover, the 2D structure provides open diffusion channels for fast Li⁺ ion transport. As a result, the sample shows excellent electrochemical performance for bifunctional lithium storage. As a lithium-ion battery anode, the capacity retention reaches 112.8 mA h g^–1 after 5000 cycles at 40 C with a fading rate of 0.288% per 100 cycles. Meanwhile, as a lithium-ion capacitor anode, it exhibits an excellent rate capacity of 120 mA h g^–1 after 5000 cycles at 500 C with nearly 100% Coulombic efficiency. The produced LTO shows much higher rate capacity and longer lifetime than the reported LTO. Density functional theory calculations also demonstrate that oxygen vacancy can facilitate Li⁺ ion diffusion kinetics. The relationship between oxygen vacancy content and Li⁺ ions diffusion energy barrier in LTO is quantified. This work pioneers a defect engineering strategy for synthesized high-performance electrode materials.

中文翻译：

氧空位增强型二维钛酸锂，可用于超快和长寿命的双功能锂存储

在Li ₄ Ti ₅ O ₁₂（LTO）中提高足够的Li ⁺离子迁移率对于高速率性能锂存储至关重要。在这里，通过一锅水热法成功地制造了超快电荷存储氧空位二维（2D）LTO纳米片。选择性地将Al ³⁺掺杂到八面体Li ⁺ / Ti ⁴⁺ 16d位点中，不仅提供大量的氧空位和适当变形的TiO ₆八面体以利于Li ⁺离子扩散，而且还充当了“柱状”以稳定Ti-O骨架。氧空位降低Li ⁺离子扩散能垒。此外，2D结构提供了开放的扩散通道，可实现快速的Li ⁺离子传输。结果，该样品显示出用于双功能锂存储的优异的电化学性能。作为锂离子电池阳极，在40 C下经过5000次循环后，容量保持率达到112.8 mA hg ^–1，每100次循环的褪色率为0.288％。同时，作为锂离子电容器阳极，它在500 C下经过5000次循环后，库仑效率高达100％，具有120 mA hg ^–1的优异倍率容量。与报告的LTO相比，生产的LTO显示出更高的倍率容量和更长的使用寿命。密度泛函理论计算还表明，氧空位可以促进Li ⁺离子扩散动力学。定量分析了LTO中氧空位含量与Li ⁺离子扩散能垒之间的关系。这项工作开创了用于合成高性能电极材料的缺陷工程策略。

更新日期：2021-04-29

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