Hierarchically nanobranch structured freestanding metallic mesh electrode for high-performance transparent flexible supercapacitor

The intense interest in wearable electronics as a futuristic technology advancing the daily life of human being is now motivating the synergetic development of high-performance transparent flexible energy storage devices, presenting challenges for supercapacitor electrodes in terms of their electrical, optical and mechanical properties. Here, we proposed a unique supercapacitor electrode with hierarchical Ni@MnO2 nanobranch structures supported on a transparent and flexible freestanding Ni-mesh via a facile electrochemical deposition method. The hierarchically nanostructured electrodes provide a large surface area for fast ion transportation, thus strongly enhancing the supercapacitor device performance (19.65 mF/cm(2)) which is nearly an order of magnitude compared to the device with planar electrodes (2.1 mF/cm(2)), while still maintaining the high transparency (77%) and super-flexibility. Besides, the device delivers a long cycling life of 98.6% retention after 10,000 cycles, and stable working performance when bended to a series of bending angles and even after repeated folding, presenting outstanding mechanical flexibility for conformal integration with curved surfaces. This hierarchically nanostructured electrode offers a facile way for capacitance enhancement in developing wearable energy-storage devices with both high optical transmittance and mechanical reliability. (C) 2021 Elsevier B.V. All rights reserved.