Self-supported metal-organic framework-based nanostructures as binder-free electrodes for supercapacitors

Metal-organic framework (MOF), an interesting class of functional inorganic material, has recently emerged as a suitable electrode material or template/percursor of electrode material for supercapacitors (SCs). The key in utilizing...

Electrochemical Improvement of the MWCNT/Al Electrodes for Supercapacitors

An original technique of chemical deposition (CVD) by catalytic pyrolysis of ethanol vapor was used to directly grow multiwall carbon nanotubes (MWCNTs) layers on aluminum foil. The grown nanotubes had excellent adhesion and direct electrical contact to the aluminum substrate. This material was perfect for use in electrochemical supercapacitors. In this work, the possibility of a significant increase in the specific capacity of MWCNTs by simple electrochemical oxidation was investigated. The optimal conditions for improving the characteristics of the MWCNT/Al electrodes were found. Electrochemical treatment of MWCNT/Al electrodes in a 0.005 M Na2SO4 solution at a potential of 4–5 V for 20–30 min increased the specific capacity of MWCNTs from 30 F/g to 140 F/g. The properties of modified nanotubes were investigated by X-ray photoelectron spectroscopy, cyclic voltammetry (CV), and impedance spectroscopy. A significant increase in the concentration of oxygen-containing functional groups on the surface of MWCNTs was found as a result of electrochemical oxidation. The modified MWCNT/Al electrodes maintained excellent stability to multiple charge–discharge cycles. After 20,000 CVs, the capacity loss was less than 5%. Thus, the results obtained significantly expanded the possibilities of using MWCNT/Al composite materials obtained by the method of direct deposition of carbon nanotubes on aluminum foil as electrodes for supercapacitors.

Nanostructured electrodes for supercapacitors

The paper presents the results of studies on the formation of planar capacitive systems based on nanoporous anodic oxide films and a conducting polymer. According to voltammetry data, the capacity of the systems under study was determined. The structure of the porous layers was judged by impedance spectroscopy and electron microscopy.