Cr2O3@TiO2 yolk/shell octahedrons derived from a metal–organic framework for high-performance lithium-ion batteries
Cr2O3@TiO2 yolk/shell octahedrons derived from a metal–organic framework for high-performance lithium-ion batteries
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DOI：
10.1016/j.micromeso.2014.10.026
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发表时间：
2015-02
影响因子：
5.2
通讯作者：
Buxue Wang;Ziqi Wang;Yuanjing Cui;Yu Yang;Zhiyu Wang;Banglin Chen;G. Qian
中科院分区：
文献类型：
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作者：
Buxue Wang;Ziqi Wang;Yuanjing Cui;Yu Yang;Zhiyu Wang;Banglin Chen;G. Qian
以金属有机骨架MIL-101（Cr 3+）为模板剂和核发生剂，合成了一种新型的纳米级蛋黄/壳八面体Cr2O3@TiO2，并将其作为锂离子电池负极材料。在纳米MIL-101（Cr ~（3+））表面包覆非晶态TiO_2壳层，在Ar气氛下煅烧，然后在空气气氛下煅烧，形成纳米Cr_2O_3@TiO_2。经热处理后，无定形TiO 2包覆的MIL-101（Cr）转变为纳米级Cr2 O3晶体，并形成多核的蛋黄/壳八面体，SEM和TEM形貌显示了这一点。所得Cr2O3@TiO 2具有中等孔隙率，BET表面积为146 m2 g-1，其Cr2 O3核的直径为10-40 nm。在0.5 C充放电倍率下，500次循环后，其可逆容量为510 mA h g− 1，远优于无TiO 2壳的裸纳米Cr2 O3，是性能最好的Cr2 O3负极材料之一。Cr2O3@TiO2电化学性能的提高主要是由于其粒径小、孔隙率适中，有利于电解质的渗透和Li+离子的快速扩散，其蛋黄/壳结构中的空隙空间缓冲了Cr2 O3的体积变化，其TiO 2壳层抑制了内部颗粒的粉碎。
To make use of a metal–organic framework MIL-101(Cr3+) as template and core generator, we report synthesis of a novel nanoscale yolk/shell octahedron of Cr2O3@TiO2and its high performance as the anode material for lithium ion battery. Nanoscale MIL-101(Cr3+) was coated with amorphous TiO2shell and calcinated under Ar and then in air atmospheres to form nanoscale Cr2O3@TiO2. After heat treatment, the amorphous TiO2coated MIL-101(Cr) was transformed into nanosized Cr2O3crystals with crystalline TiO2cover, forming multicore yolk/shell octahedrons, as demonstrated from their SEM and TEM morphologies. The resulting Cr2O3@TiO2has moderate porosity with the BET surface area of 146 m2g−1, and the diameter of its Cr2O3cores is 10–40 nm. It has demonstrated a reversible capacity of 510 mA h g−1after 500 cycles at 0.5 C charge/discharge rate, which is much better than the bare nano Cr2O3without TiO2shell, and is one of the best-performed Cr2O3anode materials. The improved electrochemical performance of Cr2O3@TiO2is attributed to its small particle size with moderate porosity for the infiltration of electrolyte and the fast diffusion of Li+ions, its void space within yolk/shell structure to buffer volumetric variation of Cr2O3and its TiO2shell to restrain pulverized inner particles.