TiO2 nanoflowers@Au@MnO2 core-shell composite based on modified Ti foil for flexible supercapacitor electrode

Abstract

Flexible supercapacitors have received increasing attention due to its portable, flexibility, lightweight and stability. Herein, the flexible supercapacitor electrode with core-shell structure is prepared by in-situ growth of 3D TiO2 nanoflowers on activated Ti foil and uniform coating of Au film and MnO2 nanowires. The porous Ti conductive substrate is achieved by adjusting HCl-KOH corrosion time, thereby providing more channels for charge transport. Free-standing 3D structure of TiO2 NFs provides more surface area to facilitate ions intercalation/deintercalation. Au thin film plays a pivotal role in enhancing conductivity of Ti/TiO2 substrate and adhesion of MnO2 nanowires. The TiO2 NFs@Au@MnO2 composite electrode performs an excellent specific capacitance (1322.5 F g−1 at 1 A g−1) and satisfying cycling stability (86.3% capacity retention after 2000 cycles). Additionally, the assembled solid-state symmetric supercapacitor also displays superior electrochemical performance (223.75 F g−1 at 0.5 A g−1), favourable rate capability (85.8% capacity retention after 2000 cycles) and remarkable flexibility. The combination of 3D architecture nanocomposite electrode with other carbon-based materials will open up a prospect for developing flexible asymmetric supercapacitors.