Abstract For aqueous supercapacitors, the working voltage is normally limited below 2 V because of the electrochemical stability of water, which limits improvement of the energy density and thus severely hinders their practical application. Herein, a flexible electrode of interconnected δ-MnO2 nanosheets anchored on activated carbon cloth with a potential window (vs Ag/AgCl) extending to 1.2 V is developed using simple one-step water bath only at 40 °C. A high specific capacitance up to 360.5 F g−1 at 1 A g−1 combining with good rate performance and electrochemical stability is delivered. Folding test indicates that the charge storage performance of the electrode has neglected degradation during the 2000 times of folding. Furthermore, a 2.4 V aqueous asymmetric supercapacitor is assembled based on the device configuration of activated carbon//δ-MnO2 and a high energy density of 49.8 Wh kg−1 at the power density of 1198.4 W kg−1 and good electrochemical stability, i.e., 90.6% capacitance retention after 5000 cycles can be achieved. Thanks to the good energy storage performance, high flexibility and simple preparation of the material, it is believed that this work provides a valuable exploration to develop high-performance flexible aqueous asymmetric energy storage devices.

中文翻译：

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锚定在活性炭布上的互连δ-MnO2纳米片作为高性能水性非对称超级电容器的柔性电极

摘要 对于水性超级电容器，由于水的电化学稳定性，其工作电压通常被限制在2 V以下，这限制了能量密度的提高，从而严重阻碍了其实际应用。在此，使用仅在 40°C 下的简单一步水浴开发了一种由互连的 δ-MnO2 纳米片组成的柔性电极，该电极锚定在活性炭布上，其电位窗口（相对于 Ag/AgCl）延伸至 1.2 V。提供了在 1 A g-1 下高达 360.5 F g-1 的高比电容以及良好的倍率性能和电化学稳定性。折叠测试表明电极的电荷存储性能在2000次折叠过程中忽略了退化。此外，一个 2。基于活性炭//δ-MnO2的器件配置组装了4 V水性不对称超级电容器，在1198.4 W kg-1的功率密度下具有49.8 Wh kg-1的高能量密度和良好的电化学稳定性，即90.6%可实现 5000 次循环后的电容保持率。由于该材料具有良好的储能性能、高柔韧性和简单的制备方法，相信该工作为开发高性能柔性水性不对称储能装置提供了宝贵的探索。