Nano-Sized Structurally Disordered Metal Oxide Composite Aerogels as High-Power Anodes in Hybrid Supercapacitors
Nano-Sized Structurally Disordered Metal Oxide Composite Aerogels as High-Power Anodes in Hybrid Supercapacitors
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DOI：
10.1021/acsnano.7b09062
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发表时间：
2018-03-01
期刊：
影响因子：
17.1
通讯作者：
Niederberger, Markus
中科院分区：
文献类型：
--
作者：
Huang, Haijian;Wang, Xing;Niederberger, Markus
介绍了一种制备高度无序晶体结构的纳米金属氧化物纳米粒子并将其加工成稳定的水分散体的一般方法。以这些纳米粒子为基块，制备了一系列纳米粒子@还原石墨烯氧化物(RGO)复合气凝胶，并将其直接用作锂离子混合超级电容器(Li-HSC)的大功率阳极。为了阐明无序度的影响，制备了颗粒尺寸相似的晶态纳米颗粒的对照样品。结果表明，与晶态样品相比，结构无序样品的电化学性能有显著提高。特别是，结构无序的NixFeyOz@rGO在5Ag(-1)下的容量为388mAhg(-1)，是结晶样品的6倍。以无序NixFeyOz@rGO为例，分析了性能提高的原因。密度泛函理论计算表明，与晶态样品相比，结构无序的NixFeyOz纳米粒子在Li+插入过程中体积膨胀较小，并表现出较大的伪电容效应。结合活性碳(AC)阴极，进行了锂离子混合超级电容器的全电池测试，结果表明，平行于AC混合系统的结构无序的金属氧化物纳米粒子@rGO在1.0-4.0V的电压范围内提供了高的能量和功率密度。这些结果表明，结构无序的纳米材料可能是探索Li-HSCs高功率阳极的感兴趣的候选材料。
A general method for preparing nano-sized metal oxide nanoparticles with highly disordered crystal structure and their processing into stable aqueous dispersions is presented. With these nanoparticles as building blocks, a series of nanoparticles@reduced graphene oxide (rGO) composite aerogels are fabricated and directly used as high-power anodes for lithium-ion hybrid supercapacitors (Li-HSCs). To clarify the effect of the degree of disorder, control samples of crystalline nanoparticles with similar particle size are prepared. The results indicate that the structurally disordered samples show a significantly enhanced electrochemical performance compared to the crystalline counterparts. In particular, structurally disordered NixFeyOz@rGO delivers a capacity of 388 mAh g(-1) at 5 A g(-1), which is 6 times that of the crystalline sample. Disordered NixFeyOz@rGO is taken as an example to study the reasons for the enhanced performance. Compared with the crystalline sample, density functional theory calculations reveal a smaller volume expansion during Li+ insertion for the structurally disordered NixFeyOz nanoparticles, and they are found to exhibit larger pseudocapacitive effects. Combined with an activated carbon (AC) cathode, full-cell tests of the lithium-ion hybrid supercapacitors are performed, demonstrating that the structurally disordered metal oxide nanoparticles@rGO parallel to AC hybrid systems deliver high energy and power densities within the voltage range of 1.0-4.0 V. These results indicate that structurally disordered nanomaterials might be interesting candidates for exploring high-power anodes for Li-HSCs.