Most manganese oxide-based electrodes used for energy-storage applications suffer from poor ion and electron transport, particularly at high mass loadings and with thick electrodes. To counter this issue, 3D electrodes were developed; however, enhancing their areal and volumetric performance at high mass loadings is still a challenge. In this study, highly compact and 3D porous manganese dioxide and holey reduced graphene oxide (3D MnO₂/HRGO) composite films were developed to ensure a high performance in supercapacitors at electrode thicknesses greater than 100 µm. The thick composite films were fabricated by the self-limiting deposition of MnO₂ on 3D HRGO hydrogel scaffolds followed by capillary evaporation-induced drying. The 3D MnO₂/HRGO electrodes optimized at a thickness of 216 μm showed outstanding specific areal and volumetric capacitances of 2.3 F cm⁻² and 108.0 F cm⁻³ at 1 mA cm⁻² and an impressive rate capability with a capacitance retention of 72.2% in the range of 1–40 mA cm⁻². Furthermore, supercapacitors assembled with the 3D MnO₂/HRGO electrodes with high mass loadings exhibited impressively high areal and volumetric energy densities of 149.7 μWh cm⁻² and 2.8 mWh cm⁻³, respectively.

大多数用于储能应用的基于氧化锰的电极都存在离子和电子传输差的问题，尤其是在高质量负载和厚电极时。为了解决这个问题，开发了 3D 电极；然而，在高质量负载下提高它们的面积和体积性能仍然是一个挑战。在这项研究中，开发了高度紧凑的 3D 多孔二氧化锰和多孔还原氧化石墨烯 (3D MnO ₂ /HRGO) 复合膜，以确保电极厚度大于 100 µm 的超级电容器的高性能。通过在 3D HRGO 水凝胶支架上自限沉积 MnO ₂然后进行毛细管蒸发诱导干燥来制造厚复合膜。3D MnO ₂在 216 μm 厚度下优化的 /HRGO 电极在 1 mA cm ^{-2 下}表现出出色的比表面积和体积电容，分别为 2.3 F cm ^-2和 108.0 F cm ^-3以及令人印象深刻的倍率性能，在该范围内的电容保持率为 72.2% 1–40 mA cm ^-2。此外，与具有高质量负载的 3D MnO ₂ /HRGO 电极组装的超级电容器分别显示出令人印象深刻的高面积和体积能量密度，分别为 149.7 μWh cm ^-2和 2.8 mWh cm ^-3。