In‐Plane Vacancy‐Enabled High‐Power Si–Graphene Composite Electrode for Lithium‐Ion Batteries
In‐Plane Vacancy‐Enabled High‐Power Si–Graphene Composite Electrode for Lithium‐Ion Batteries
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DOI：
10.1002/aenm.201100426
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发表时间：
2011-11
影响因子：
27.8
通讯作者：
Xin Zhao;C. Hayner;M. Kung;H. Kung
中科院分区：
文献类型：
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作者：
Xin Zhao;C. Hayner;M. Kung;H. Kung
当前对具有柔性和/或紧凑配置的更有效的电能存储设备的贪得无厌的需求，由具有不断增加的功能复杂性的便携式电子设备的激增所提供，当可拆卸艾德车辆成为优选的运输模式并且从间歇源的能量收集演变成实践规范时，将更加难以满足。[ 1-4 ]将具有高倍率性能的超级电容器和具有高能量密度的可再充电电池的吸引人的特征结合到单个单元中将使得能够设计用于可持续电力输送的高容量能量存储装置。[ 5-7 ]然而，到目前为止，这一目标已被证明是难以实现的。用于提高锂离子电池的电极材料的功率容量的策略通常涉及减小活性电荷存储材料的畴尺寸（例如，Si）以缩短离子扩散路径，例如通过在纳米泡沫和金属网上制造垂直排列的1-D纳米结构或纳米涂层。[ 8，9 ]通常，由于电极中活性组分的质量分数低，这种方法的总电荷存储容量有限。使用陶瓷模板制造多孔电极框架是另一种方法[ 10-12 ]，但是这些多孔电极引入了不同的问题，例如由机械脆性造成的构型可弯曲性和由减小的填充密度引起的体积能量密度的急剧下降。在这里，我们证明，石墨烯片具有高密度的面内，大小的碳空位可以转化为一个灵活的，3-D导电石墨烯支架具有优良的横面离子扩散和耐受结构变形。当用作结构平台以结合高存储容量材料（例如Si）时，获得具有增强的可接近内部和高倍率容量的稳定的自支撑复合电极，代表了对高性能Li离子电池有吸引力的电极候选者。此外，该复合材料是可延展的，并提供了结构柔性，并且可以通过成本有效的方法生产。我们的3-D石墨烯支架是用对齐的石墨烯片构建的，石墨烯片来自剥离的氧化石墨烯片，其中通过简单的湿化学方法引入了面内纳米级的碳空位。它提供了优于所报道的电极系统的有利特征的组合：
IO N The current insatiable appetite for more effi cient electrical energy storage devices with a fl exible and/or compact confi guration, fed by the proliferation of portable electronics with ever increasing functional complexity, will be even more diffi cult to satisfy when electrifi ed vehicles become the preferred mode of transportation, and energy harvesting from intermittent sources evolves into the practiced norm. [ 1–4 ] Incorporation of the attractive features of supercapacitors with high rate performance and rechargeable batteries with high energy densities into a single unit would enable the design of high-capacity energy storage devices for sustainable power delivery. [ 5–7 ] Thus far, however, this goal has proved to be diffi cult to attain. Strategies used to boost the power capability of electrode materials for Li-ion batteries generally involve reducing the domain size of the active charge-storage material (e.g., Si) in the electrode to shorten the ion diffusion paths, such as by fabricating vertically aligned 1-D nanostructures or ultrathin coatings on nanofoams and metallic mesh. [ 8 , 9 ] Generally, such an approach suffers from limited overall charge storage capacity due to a low mass fraction of the active component in the electrode. Fabricating porous electrode frameworks using sacrifi cial templates is another approach, [ 10–12 ] but these porous electrodes introduce different problems, such as confi gurational infl exibility imposed by mechanical fragility and a dramatic drop in volumetric energy density consequential of reduced packing densities. Here we demonstrate that graphene sheets possessing a high density of in-plane, -sized carbon vacancies can be transformed into a fl exible, 3-D conducting graphenic scaffold with excellent crossplane ion diffusivity and tolerance to structural deformation. When employed as a structural platform to incorporate high storage-capacity materials, such as Si, a stable, self-supporting composite electrode with enhanced accessible interior and high rate capacity is obtained, representing an attractive electrode candidate towards high-performance Li-ion batteries. Furthermore, the composite is ductile and offers confi gurational fl exibility, and can be produced by cost-effective processes. Our 3-D graphenic scaffold was constructed with aligned graphene sheets, derived from exfoliated graphene oxide sheets into which in-plane, nm-sized carbon vacancies were introduced by a facile wet chemical method. It confers a combination of advantageous features over reported electrodes systems: