Si Haochen, Sun Li, Zhang Yuanxing, Wu Lin, Zhang Yu, Zhang Yihe
Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid Wastes, National Laboratory of Mineral Materials, School of Materials Science and Technology, China University of Geosciences, Beijing, 100083, PR China.
Dalton Trans. 2020 Feb 5;49(5):1637-1645. doi: 10.1039/c9dt04391h.
Despite its high theoretical capacitance, molybdenum dioxide still cannot be well applied in supercapacitors due to its low conductivity and structural instability. Generally, compositing molybdenum dioxides with carbon materials can provide new possibilities. In this work, we successfully fabricated a budding-branch like MoO2@C composite wrapped by carbon nanotubes (CNTs). Different from those MoO2 nanodots synthesized by traditional approaches, the MoO2 nanodots in this composite were distributed uniformly inside the carbon rods, which effectively alleviated their self-aggregation and benefited their electron transportation. The introduction of the CNTs further provided the composite with better contact with the electrolyte and increased charge transfer. The prepared MoO2@C/CNT electrode exhibits a superior specific capacitance of 1667.2 F g-1 at 1 A g-1 and an excellent reversibility of 92.8% capacitance retention after 3000 cycles. Furthermore, asymmetric supercapacitor devices based on the MoO2@C/CNT composite and active carbon were assembled, which showed promising electrochemical properties at an extended operating voltage of 1.4 V and could light a green LED device for 15 minutes after charging for 30 s.
尽管二氧化钼具有较高的理论电容，但由于其低导电性和结构不稳定性，仍无法很好地应用于超级电容器。一般来说，将二氧化钼与碳材料复合可以提供新的可能性。在这项工作中，我们成功制备了一种被碳纳米管（CNT）包裹的芽状分支结构的MoO2@C复合材料。与传统方法合成的MoO2纳米点不同，该复合材料中的MoO2纳米点均匀分布在碳棒内部，有效减轻了它们的自聚集，有利于电子传输。碳纳米管的引入进一步使复合材料与电解质有更好的接触并增加了电荷转移。制备的MoO2@C/CNT电极在1 A g-1电流密度下表现出1667.2 F g-1的优异比电容，在3000次循环后电容保持率高达92.8%，具有出色的可逆性。此外，基于MoO2@C/CNT复合材料和活性炭组装了不对称超级电容器器件，该器件在1.4 V的扩展工作电压下表现出良好的电化学性能，充电30 s后可为绿色LED器件供电15分钟。
