High-performance supercapacitors based on MnO2 tube-in-tube arrays

MnO2 tube-in-tube arrays supported on carbon fiber cloth (MnO2 TTAs/CFC) were designed and synthesized. As a robust integrated 3D electrode with high utilization rate and fast ion transport, the MnO2 TTAs/CFC exhibits a high areal specific capacitance (C-sp) of 322 mF cm(-2) (similar to 1007 F g(-1) for MnO2 at 0.125 A g(-1)) and superior cycling stability (95.1% retention of the initial C-sp after 2000 cycles) at a high scan rate of 100 mV s(-1). The assembled flexible all-solid-state symmetric supercapacitors (SSCs) based on MnO2 TTAs/CFC electrodes show a high volumetric energy density of 0.073 mW h cm(-3) at a power density of 25 W kg(-1) and high cycling stability (96.4% retention of the initial C-sp after 2000 cycles). This study demonstrates that the 3D MnO2 TTAs/CFC electrodes hold great potential for use in flexible energy storage devices.