High-performance transparent and flexible supercapacitor electrode based on nanopetal-structured MnO2

The rapid development in portable and wearable electronics have stimulated the interest in the integrated energy storage devices. Flexible and transparent supercapacitors are responsible candidates for energy storage devices due to the high performance, quick charge/discharge and safety operation. Specially, it is a great challenge to fabricate transparent flexible electrodes serving as the critical component of supercapacitor. Herein, we constructure a novel and unique hierarchical nanopetal-structured MnO2 on the freestanding metallic mesh framework as the supercapacitor electrode. The freestanding nanostructured electrode without substrate-supported shows highly transparent (similar to 81.6%) and ultrathin thickness (similar to 9 mu m), moreover, the ultrathin thickness enabling the electrode with significant flexibility for further wearable systems. The as-fabricated nanostructured electrode provides a large surface area, which delivers an enhanced areal capacitance up to 24.8 mF/cm(2) that 2.5 times to the electrode without nanostructures. Additionally, the symmetric solidstate supercapacitors inherit the super-flexibility from the freestanding nanostructured electrode that enable the devices to be foldable and even crumpled into any objects. The solidstate supercapacitors can also maintain the long cycling stability of 99% retention after 10000 charge-discharge cycles, demonstrating high mechanical stability.