Morphology memory but reconstructing crystal structure: porous hexagonal GeO2 nanorods for rechargeable lithium-ion batteries.
Morphology memory but reconstructing crystal structure: porous hexagonal GeO2 nanorods for rechargeable lithium-ion batteries.
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DOI：
10.1039/c7nr00599g
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发表时间：
2017-03
期刊：
影响因子：
6.7
通讯作者：
Wei Wei-Wei;Fangfang Jia;Peng Qu;Zhongning Huang;Hua Wang;Lin Guo
中科院分区：
文献类型：
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作者：
Wei Wei-Wei;Fangfang Jia;Peng Qu;Zhongning Huang;Hua Wang;Lin Guo
六方GeO2具有较高的理论可逆容量和较低的工作电压，被认为是一种很有前途的锂离子电池负极材料。与其他合金型负极材料类似，GeO2在实际应用中面临着锂/脱锂循环过程中体积变化大、容量衰减快等问题。构建独特的GeO2纳米结构被认为是解决这一快速容量退化问题的有效策略。然而，由于Ge前驱体在水溶液中的快速水解，GeO2纳米材料的可控合成受到了挑战。在这项工作中，我们报道了一种简单的方法，以正交晶Ca2Ge7O16纳米棒为牺牲模板，以HNO3为腐蚀剂合成GeO2纳米棒。利用Ca2Ge7O16纳米棒的形态记忆特性，制备的多孔六方GeO2纳米棒具有优异的电化学性能，50次循环后比容量高达747 mA·h·g-1，这归功于GeO2纳米棒的多孔性和一维纳米结构。这种简单的形态记忆但重构晶体结构的方法可以推广到其他GeO2纳米结构的可控制备，并获得更高效的负极材料。
Hexagonal GeO2, with high theoretical reversible capacity and low operating voltage, is regarded as a promising anode material for Li ion batteries. Being similar to other alloy type anode materials, the practical application of GeO2 is confronted with large volume change and fast capacity fading during lithiation/delithiation cycles. Constructing unique GeO2 nanostructures is proposed as an effective strategy to address this issue of fast capacity degradation. However, the controllable synthesis of GeO2 nanomaterials is challenged due to the fast hydrolysis of Ge precursors in aqueous solution. In this work, we report a simple strategy to synthesize GeO2 nanorods by using orthorhombic Ca2Ge7O16 nanorods as the sacrificial template with HNO3 as the etching agent. With the morphology memory of orthorhombic Ca2Ge7O16 nanorods, the as-prepared porous hexagonal GeO2 nanorods exhibit excellent electrochemical performance with a high capacity of 747 mA h g-1 after 50 cycles, which should be attributed to the porous and one dimensional nanostructure of GeO2 nanorods. This facile 'morphology memory but restructuring crystal structure' method could be extended to the controllable preparation of other GeO2 nanostructures, and achieve more efficient anode materials.