Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, College of Environmental and Chemical Engineering, Shanghai University of Electric Power , Shanghai 200090, China.
Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Institute of New Energy, Fudan University , Shanghai 200433, China.
ACS Appl Mater Interfaces. 2017 Nov 22;9(46):40394-40403. doi: 10.1021/acsami.7b14761. Epub 2017 Nov 7.
Manganese oxides (MnO) are regarded as typical and promising electrode materials for supercapacitors. However, the practical electrochemical performance of MnO is far from its theoretical value. Nowadays, numerous efforts are being devoted to the design and preparation of nanostructured MnO with the aim of improving its electrochemical properties. In this work, ultralong MnO nanowires were fabricated in a process induced by carbon quantum dots (CQDs); subsequently, a binder-free flexible electrode membrane was easily obtained by vacuum filtration of the MnO nanowires. The effects of the CQDs not only induced the formation of one-dimensional nanostructured MnO, but also significantly improved the wettability between electrode and electrolyte. In other words, the MnO membrane demonstrated a superhydrophilic character in aqueous solution, indicating the sufficient and abundant contact probability between electrode and electrolyte. The binder-free flexible MnO electrode exhibited a preeminent specific capacitance of 340 F g at 1 A g; even when the current density reached 20 A g, it still maintained 260 F g (76% retention rate compared to that at 1 A g). Moreover, it also showed good cycling stability with 80.1% capacity retention over 10 000 cycles at 1 A g. Furthermore, an asymmetric supercapacitor was constructed using the MnO membrane and active carbon as the positive and negative electrodes, respectively, which exhibited a high energy density of 33.6 Wh kg at 1.0 kW kg, and a high power density of 10 kW kg at 12.5 Wh kg.
二氧化锰（MnO）被认为是超级电容器的典型和有前途的电极材料。然而，MnO 的实际电化学性能远低于其理论值。如今，人们正在致力于设计和制备纳米结构的 MnO，以提高其电化学性能。在这项工作中，通过碳量子点（CQDs）诱导的过程制备了超长的 MnO 纳米线；随后，通过 MnO 纳米线的真空过滤很容易得到无粘合剂的柔性电极膜。CQDs 的作用不仅诱导了一维纳米结构 MnO 的形成，而且显著提高了电极和电解质之间的润湿性。换句话说，MnO 膜在水溶液中表现出超亲水性，表明电极和电解质之间有足够和丰富的接触概率。无粘合剂的柔性 MnO 电极具有卓越的比电容，在 1 A g 时为 340 F g；即使电流密度达到 20 A g，它仍保持 260 F g（与 1 A g 时相比保持率为 76%）。此外，它还表现出良好的循环稳定性，在 1 A g 下 10000 次循环后容量保持率为 80.1%。此外，使用 MnO 膜和活性炭作为正负极构建了非对称超级电容器，其在 1.0 kW kg 时具有 33.6 Wh kg 的高能量密度，在 12.5 Wh kg 时具有 10 kW kg 的高功率密度。
