Atomic-scale investigation on lithium storage mechanism in TiNb2O7
Atomic-scale investigation on lithium storage mechanism in TiNb2O7
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DOI：
10.1039/c0ee00808g
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发表时间：
2011-08-01
影响因子：
32.5
通讯作者：
Chen, Liquan
中科院分区：
文献类型：
--
作者：
Lu, Xia;Jian, Zelang;Chen, Liquan
采用固相反应法制备了单斜层状氧化钛（TiNb2O7）作为锂离子电池的负极材料。在电流密度为30mA g(-1)（约0.1C）时，TiNb2O7电极的锂存储容量为281 mAh g(-1)，初始库仑效率高达93%。在0.8 ~ 3.0 V电压范围内，锂离子与Li/Li+的平均插入电压约为1.64 V。电极具有较小的电压迟滞（30 mA g（-1）时0.1 V）和良好的容量保持。这种优异的电化学性能使TiNb2O7成为替代尖晶石Li4Ti5O12的最有希望应用于混合动力汽车和大型固定式锂离子电池的负极材料之一。此外，我们利用先进的球差校正扫描透射电子显微镜（STEM）展示了TiNb2O7和锂化TiNb2O7的晶体结构，在原子尺度上描绘了Li， Ti， Nb和O原子占据的晶格位。揭示了与第一性原理预测相一致的可能的锂化/脱蚀过程和反应机理。
Titanium niobium oxide (TiNb2O7) with a monoclinic layered structure has been synthesized by a solid state reaction method as an anode candidate for Li-ion batteries. The TiNb2O7 electrode shows a lithium storage capacity of 281 mAh g(-1) with an initial coulombic efficiency as high as 93% at a current density of 30mA g(-1) (ca. 0.1C). The average lithium insertion voltage is about 1.64 V vs. Li/Li+ at a voltage range of 0.8-3.0 V. The electrodes exhibit small voltage hysteresis (c. a. 0.1 V at 30 mA g(-1)) and good capacity retention. Such superior electrochemical performance of TiNb2O7 makes it one of the most promising anode materials to replace spinel Li4Ti5O12 for applications in hybrid vehicles and large scale stationary Li-ion batteries. In addition, we demonstrate crystal structures of TiNb2O7 and lithiated TiNb2O7 using advanced spherical-aberration-corrected scanning transmission electron microscopy (STEM), to picture the lattice sites occupied by the Li, Ti, Nb and O atoms at atomic-scale. Possible lithiation/delithiation processes and reaction mechanisms are revealed in consistence with first-principles prediction.