Department of Mechanical Engineering, University of South Carolina, 300 Main Street, Columbia, South Carolina 29208, United States.
Nano Lett. 2011 Mar 9;11(3):1215-20. doi: 10.1021/nl104205s. Epub 2011 Feb 9.
We demonstrate the design and fabrication of a novel flexible nanoarchitecture by facile coating ultrathin (several nanometers thick) films of MnO2 to highly electrical conductive Zn2SnO4 (ZTO) nanowires grown radially on carbon microfibers (CMFs) to achieve high specific capacitance, high-energy density, high-power density, and long-term life for supercapacitor electrode applications. The crystalline ZTO nanowires grown on CMFs were uniquely served as highly conductive cores to support a highly electrolytic accessible surface area of redox active MnO2 shells and also provide reliable electrical connections to the MnO2 shells. The maximum specific capacitances of 621.6 F/g (based on pristine MnO2) by cyclic voltammetry (CV) at a scan rate of 2 mV/s and 642.4 F/g by chronopotentiometry at a current density of 1 A/g were achieved in 1 M Na2SO4 aqueous solution. The hybrid MnO2/ZTO/CMF hybrid composite also exhibited excellent rate capability with specific energy of 36.8 Wh/kg and specific power of 32 kW/kg at current density of 40 A/g, respectively, and good long-term cycling stability (only 1.2% loss of its initial specific capacitance after 1000 cycles). These results suggest that such MnO2/ZTO/CF hybrid composite architecture is very promising for next generation high-performance supercapacitors.
我们通过简便地在高度导电的 Zn2SnO4（ZTO）纳米线上涂覆几纳米厚的 MnO2 薄膜，展示了一种新型的柔性纳米结构的设计和制造，这些 ZTO 纳米线径向生长在碳纤维微纤维（CMFs）上，可实现超级电容器电极应用的高比电容、高能量密度、高功率密度和长循环寿命。生长在 CMFs 上的结晶 ZTO 纳米线独特地作为高导电性核心，支持氧化还原活性 MnO2 壳的高电解质可及表面积，并为 MnO2 壳提供可靠的电连接。在 1 M Na2SO4 水溶液中，通过循环伏安法（CV）以 2 mV/s 的扫描速率实现了 621.6 F/g（基于原始 MnO2）的最大比电容，通过恒电流计时法以 1 A/g 的电流密度实现了 642.4 F/g 的最大比电容。MnO2/ZTO/CMF 混合复合材料还表现出优异的倍率性能，在 40 A/g 的电流密度下，比能量分别为 36.8 Wh/kg 和比功率为 32 kW/kg，并且具有良好的长期循环稳定性（在 1000 次循环后仅损失其初始比电容的 1.2%）。这些结果表明，这种 MnO2/ZTO/CF 混合复合结构非常有希望用于下一代高性能超级电容器。
