Abstract Novel three-dimensional (3D) MnO2 hierarchical microspheres (HMSs) assembled by porous nanoplates with a thickness of 50–130 nm were solvothermally prepared and combined with subsequent annealing of the precursors at 450 °C in air. Such MnO2 HMSs possessed a BET specific surface area of 48.6 m2 g−1 with a mean pore size of about 14.5 nm, respectively. The shapes and size of final MnO2 products can be controlled by changing the amount of surfactant cetyltrimethylammonium bromide (CTAB) and volume ratios of water to ethanol. Irregular particles were produced in the absence of water, and the morphologies of MnO2 samples transformed from well-defined HMSs to microcubes with the content of water increasing. These MnO2 HMSs show both a high specific capacitance of 129 F g−1 at 0.5 A g−1 in 0.5 M of Na2SO4 aqueous solution and a good cycling stability of 98.6% capacitance retention after 1000 cycles at a current density of 1 A g−1, demonstrating very excellent electrochemical performance. The result suggests that such MnO2 HMSs may be a promising electrode material in the field of supercapacitors due to its mesoporous and integrated hierarchical structure.

中文翻译：

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由多孔纳米板组装的 MnO2 分级微球用于高性能超级电容器

摘要 溶剂热法制备了由厚度为 50-130 nm 的多孔纳米板组装的新型三维 (3D) MnO2 分级微球 (HMS)，并结合随后在 450 °C 空气中对前体进行退火。这种 MnO2 HMS 的 BET 比表面积为 48.6 m2 g-1，平均孔径分别约为 14.5 nm。可以通过改变表面活性剂十六烷基三甲基溴化铵 (CTAB) 的用量和水与乙醇的体积比来控制最终 MnO2 产品的形状和尺寸。在无水的情况下会产生不规则的颗粒，随着水含量的增加，MnO2 样品的形态从明确的 HMS 转变为微立方体。这些 MnO2 HMS 在 0.5 A g-1 中显示出 129 F g-1 的高比电容。5 M 的 Na2SO4 水溶液和良好的循环稳定性，在 1 A g-1 的电流密度下循环 1000 次后电容保持率为 98.6%，表明非常优异的电化学性能。结果表明，这种MnO2 HMSs由于其介孔和集成的分级结构，可能是超级电容器领域有前途的电极材料。