Ordered Large-Pore Mesoporous Li4Ti5O12 Spinel Thin Film Electrodes with Nanocrystalline Framework for High Rate Rechargeable Lithium Batteries: Relationships among Charge Storage, Electrical Conductivity, and Nanoscale Structure
Ordered Large-Pore Mesoporous Li4Ti5O12 Spinel Thin Film Electrodes with Nanocrystalline Framework for High Rate Rechargeable Lithium Batteries: Relationships among Charge Storage, Electrical Conductivity, and Nanoscale Structure
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DOI：
10.1021/cm202185y
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发表时间：
2011-10-11
影响因子：
8.6
通讯作者：
Brezesinski, Torsten
中科院分区：
文献类型：
--
作者：
Haetge, Jan;Hartmann, Pascal;Brezesinski, Torsten
采用软模板法合成了具有纳米晶骨架的介孔钛酸锂（Li 4 Ti 5 O 12）薄膜电极，并对其进行了表征。各种国家的最先进的技术，包括电子显微镜，掠入射小角度X射线散射，阻抗谱，飞行时间二次离子质谱，和X射线光电子能谱验证溶胶-凝胶衍生的Li 4 Ti 5 O 12材料在这项工作中采用的是很好地定义在纳米尺度和微米尺度。此外，数据显示，薄膜在650 ℃空气中退火后高度结晶，并采用纯相形式的尖晶石结构。数据还表明，最初的无定形框架的转换几乎没有成本平均直径为18 nm的孔的扭曲的立方网络的排序。除了结构表征，我们还研究了导电性和充电/放电行为，并显示出生产具有中孔形态的高质量材料的好处。介孔Li 4 Ti 5 O 12薄膜电极不仅在短充电时间内表现出增强的锂离子存储能力，而且能够在高达MC的速率下保持稳定的循环性能。我们认为，开放的纳米级孔隙率与导电性的普通散装纳米晶Li 4 Ti 5 O 12的相同的顺序的独特组合是负责在这些薄膜材料中观察到的容易的锂嵌入。
Herein is reported the soft-templating synthesis and characterization of mesoporous lithium titanate (Li4Ti5O12) thin film electrodes with a nanocrystalline framework. Various state-of-the-art techniques, including electron microscopy, grazing incidence small-angle X-ray scattering, impedance spectroscopy, time-of-flight secondary ion mass spectrometry, and X-ray photoelectron spectroscopy verify that the sol gel derived Li4Ti5O12 materials employed in this work are well-defined at both the nanoscale and the microscale. In addition, the data show that the thin films are highly crystalline after annealing in air at 650 degrees C and adopt the spinel structure in phase-pure form. The data also show that the conversion of the initially amorphous framework comes at little cost to the ordering of the distorted cubic network of pores averaging 18 nm in diameter. Apart from the structural characterization, we also examine the electrical conductivity and the charging/discharging behavior and show the benefits of producing a high quality material with mesoporous morphology. Mesoporous Li4Ti5O12 thin film electrodes not only exhibit enhanced lithium ion storage capabilities at short charging times but also are able to maintain stable cycling performance at rates as high as MC. We contend that the unique combination of open nanoscale porosity with electrical conductivity of the same order as that of ordinary bulk nanocrystalline Li4Ti5O12 is responsible for the facile lithium intercalation observed in these thin film materials.