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

Abstract

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 (∼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.