3D hierarchical MnO2 microspheres with ultrathin nanosheets structure and high specific surface area (184.32 m2 g-1) are synthesized by rapid microwave heating method in just 10 minutes. In this work ionic electrlolyte (EMIMBF4/DMF) based asymmetric supercapacitor device is successfuly prepared by using 3D hierarchical MnO2 microspheres as cathode and active carbon as anode materials. The (EMIMBF4/DMF) electrolyte enables significant enhancement in the potential windows of individual electrode materials and asymmetric device which results in much improved electrochemical performance. Asymmetric device operates successfully within a potential window of 3.0 V and exhibits outstanding energy density of 105 Wh kg-1 at a power density of 1494 W kg-1 with good cycling life stability (20 % loss after 6000 cycles) at much higher current density 6 A g-1. Moreover 3D hierarchical MnO2 microspheres also exhibit an outsatnding Li ion storage performance with the discharge capacity of 715 mAh g-1 even after 200 cycles at a current density of 300 mA g-1. The discharge capacity retention (78 % @ 2nd cycle) after 200 cycles at 300 mA g-1 is the highest amongst all the reported anode materials based on MnO2. High specific capacities and outstanding cyclability further indicates its strong potential as an anode of lithium-ion battery. The promising energy storage applications can be ascribed to high specific surface area, mesoporous structure and ultrathin nanosheets building blocks of MnO2 microspheres.

中文翻译：

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3D分层MnO2微球：高性能超级电容器和锂离子电池的潜在材料

通过快速微波加热法在短短10分钟内合成具有超薄纳米片结构和高比表面积（184.32 m2 g-1）的3D分层MnO2微球。在这项工作中，通过使用3D分层MnO2微球作为阴极并使用活性炭作为阳极材料成功地制备了基于离子电解质（EMIMBF4 / DMF）的不对称超级电容器。（EMIMBF4 / DMF）电解质可以显着提高单个电极材料和不对称器件的电势窗口，从而大大改善电化学性能。非对称器件在3.0 V的电势窗口内成功运行，并在功率密度为1494 W kg-1的情况下表现出出色的能量密度为105 Wh kg-1，在更高的电流密度下具有良好的循环寿命稳定性（6000次循环后损耗20％） 6 A g-1。此外，即使在200 mA循环下以300 mA g-1的电流密度放电后，3D分层MnO2微球也具有出众的Li离子存储性能，放电容量为715 mAh g-1。在所有报告的基于MnO2的负极材料中，200 mA循环200次循环后的放电容量保持率（第二循环时为78％）是最高的。高比容量和出色的可循环性进一步表明了其作为锂离子电池负极的强大潜力。前景广阔的储能应用可以归因于MnO2微球的高比表面积，中孔结构和超薄纳米片构建块。在所有报告的基于MnO2的负极材料中，200 mA循环200次循环后的放电容量保持率（第二循环时为78％）是最高的。高比容量和出色的可循环性进一步表明了其作为锂离子电池负极的强大潜力。前景光明的储能应用可以归因于MnO2微球的高比表面积，中孔结构和超薄纳米片构建块。在所有报告的基于MnO2的负极材料中，200 mA循环200次循环后的放电容量保持率（第二循环时为78％）是最高的。高比容量和出色的可循环性进一步表明了其作为锂离子电池负极的强大潜力。前景广阔的储能应用可以归因于MnO2微球的高比表面积，中孔结构和超薄纳米片构建块。