Polypyrrole-coated hierarchical porous composites nanoarchitectures for advanced solid-state flexible hybrid devices

Design and fabrication of advanced functional materials is essential but still a challenge for current energy storage devices. Herein, polypyrrole coated highly porous vanadium oxide (V₂O₅at Ppy) nanorod and nanoplate arrays with large mass loadings, have been successfully constructed on carbon felt (CF) via a facile solvothermal reaction followed by in-situ polymerization technique. Interestingly, the structure of the V₂O₅ thin films can be simply tuned from porous nanoplates to nanorods with controlled calcination time. In addition, MnO₂ nanowires with Ppy coating were also grown on the CF substrates to form MnO₂at Ppy/CF electrode through the similar method. As integrate electrodes for energy storage devices, V₂O₅at Ppy/CF nanorods demonstrate more superior electrochemical properties compared to V₂O₅at Ppy/CF nanoplates. By virtue of their intriguing structural features and uniformly Ppy coating, a solid-state flexible hybrid device (SFHD) based on V₂O₅at Ppy/CF and MnO₂at Ppy/CF as the negative and positive electrode, respectively, manifests outstanding cycling stability (approximately 89% retention even after 20,000 cycles), excellent mechanical flexibility, and remarkable energy density (28.6Whkg^-1 at power density of around 200Wkg^-1), which makes it hold great potential to be unexceptionably flexible devices for portable and wearable electronics.