High-performance electrochemical capacitors using electrodeposited MnO_2 on carbon nanotube array grown on carbon fabric

摘要

Carbon fabric (CF)-carbon nanotube array (CNTA)/MnO_2 composites with a 3D porous structure are prepared by the electrochemical deposition for high-performance electrochemical capacitors. MnO_2 nanoflowers assembled with the petal-like nanosheets uniformly attach on the surface of CNTs. Electrochemical characterization indicates that the maximum specific capacitance of CF-CNTA/MnO_2 reach to 740 F g~(-1) (based on MnO_2 alone) with a mass loading of 0.34 mg cm~(-2) at the scan rate of 2 mV s~(-1), which is much better than that of MnO_2 electrodeposited on the stainless steel and the CF. And the specific capacitance can remain 326 Fg~(-1) even with a mass loading of 4.09 mg cm~(-2). While a reasonable area-normalized capacitance of 2081 mF cm~(-2) is achieved with this high mass loading at 0.1 mV s~(-1). The rate capability measurement shows the CF-CNTA/MnO_2 achieved a high retention of 70% with a scan rate range of 2-200 mV s~(-1), which outperform others 3D porous MnO_2-based electrodes reported previously. These excellent electrochemical performances are attributed to large surface area, 3D porous structure and aligned ion diffusion channels of the CF-CNTA/MnO_2 composite electrodes.