Zheng Donghui, Li Man, Li Yongyan, Qin Chunling, Wang Yichao, Wang Zhifeng
School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300130, China.
School of Life and Environmental Sciences, Deakin University, Waurn Ponds, VIC 3216, Australia.
Beilstein J Nanotechnol. 2019 Jan 25;10:281-293. doi: 10.3762/bjnano.10.27. eCollection 2019.
Developing a facile and environmentally friendly approach to the synthesis of nanostructured Ni(OH) electrodes for high-performance supercapacitor applications is a great challenge. In this work, we report an extremely simple route to prepare a Ni(OH) nanopetals network by immersing Ni nanofoam in water. A binder-free composite electrode, consisting of Ni(OH) nanopetals network, Ni nanofoam interlayer and Ni-based metallic glass matrix (Ni(OH)/Ni-NF/MG) with sandwich structure and good flexibility, was designed and finally achieved. Microstructure and morphology of the Ni(OH) nanopetals were characterized. It is found that the Ni(OH) nanopetals interweave with each other and grow vertically on the surface of Ni nanofoam to form an "ion reservoir", which facilitates the ion diffusion in the electrode reaction. Electrochemical measurements show that the Ni(OH)/Ni-NF/MG electrode, after immersion in water for seven days, reveals a high volumetric capacitance of 966.4 F/cm at a current density of 0.5 A/cm. The electrode immersed for five days exhibits an excellent cycling stability (83.7% of the initial capacity after 3000 cycles at a current density of 1 A/cm). Furthermore, symmetric supercapacitor (SC) devices were assembled using ribbons immersed for seven days and showed a maximum volumetric energy density of ca. 32.7 mWh/cm at a power density of 0.8 W/cm, and of 13.7 mWh/cm when the power density was increased to 2 W/cm. The fully charged SC devices could light up a red LED. The work provides a new idea for the synthesis of nanostructured Ni(OH) by a simple approach and ultra-low cost, which largely extends the prospect of commercial application in flexible or wearable devices.
开发一种简便且环保的方法来合成用于高性能超级电容器应用的纳米结构氢氧化镍电极是一项巨大挑战。在这项工作中，我们报告了一种极其简单的路线，即通过将镍纳米泡沫浸入水中来制备氢氧化镍纳米花瓣网络。设计并最终实现了一种无粘结剂复合电极，它由具有三明治结构且柔韧性良好的氢氧化镍纳米花瓣网络、镍纳米泡沫中间层和镍基金属玻璃基体（Ni(OH)/Ni-NF/MG）组成。对氢氧化镍纳米花瓣的微观结构和形态进行了表征。发现氢氧化镍纳米花瓣相互交织并垂直生长在镍纳米泡沫表面，形成一个“离子库”，这有利于电极反应中的离子扩散。电化学测量表明，浸入水中七天后的Ni(OH)/Ni-NF/MG电极在电流密度为0.5 A/cm时展现出966.4 F/cm³的高体积电容。浸入五天的电极表现出优异的循环稳定性（在电流密度为1 A/cm下3000次循环后初始容量的83.7%）。此外，使用浸入七天的条带组装了对称超级电容器（SC）器件，在功率密度为0.8 W/cm³时显示出约32.7 mWh/cm³的最大体积能量密度，当功率密度增加到2 W/cm³时为13.7 mWh/cm³。完全充电的SC器件能够点亮一个红色发光二极管。这项工作为通过简单方法和超低成合纳米结构氢氧化镍提供了新思路，极大地扩展了其在柔性或可穿戴设备中的商业应用前景。
