Abstract Trimanganese tetraoxide (Mn3O4) nanoframeworks were successfully prepared using a novel and facile hydrothermal route based on the redox–reaction between KMnO4 and formamide. The volume ratio between formamide and water has a crucial effect on the sample's morphology. When applied as the electrode material for supercapacitors, Mn3O4 nanoframeworks delivered a high specific capacity of 568 F g−1 at 0.5 A g−1 and excellent capacity retention of 98.3% after 5000 continuous cycles at 5 A g−1. The excellent performance was ascribed to its unique hollow and mesoporous features. Furthermore, Mn3O4//Bi2O3 asymmetric supercapacitor (ASC) was assembled using Mn3O4 nanoframeworks as a positive electrode and Bi2O3 nanoflowers as a negative electrode, respectively. The device delivered a maximum energy density of 16.4 W h kg−1 at 187.5 W kg−1. A Mn3O4//Bi2O3 ASC device can drive a mini–fan, indicating that Mn3O4 nanoframework is a potential positive electrode material for ASCs.

中文翻译：

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四氧化三锰纳米框架：形态控制的合成及其在不对称超级电容器中的应用

摘要 基于 KMnO4 与甲酰胺之间的氧化还原反应，使用一种新颖且简便的水热途径成功制备了四氧化三锰 (Mn3O4) 纳米框架。甲酰胺和水的体积比对样品的形态有至关重要的影响。当用作超级电容器的电极材料时，Mn3O4 纳米框架在 0.5 A g-1 下可提供 568 F g-1 的高比容量，在 5 A g-1 下连续循环 5000 次后容量保持率高达 98.3%。优异的性能归功于其独特的中空和介孔特性。此外，分别使用Mn3O4纳米框架作为正极和Bi2O3纳米花作为负极组装了Mn3O4//Bi2O3不对称超级电容器（ASC）。该器件在 187.5 W kg-1 时提供了 16.4 W h kg-1 的最大能量密度。