Electrophoretic Fabrication and Characterizations of Manganese Oxide/Carbon Nanotube Nanocomposite Pseudocapacitors

This study reports the electrochemical performance and stability of MnOx-multiwall carbon nanotubes (MWCNTs) nanocomposite/Ni pseudocapacitor electrodes fabricated by a modified electrophoretic deposition (EPD) method. The nanocomposite electrode consisting of highly dispersed manganese oxide on MWCNTs was synthesized by a redox titration method at room temperature. The electrochemical properties of the electrode were demonstrated by cyclic voltammetry. The mean specific capacitances at a constant scan rate of 100 mV/s of MnOx-MWCNTs nanocomposites without and with heat treatment at temperatures 150, 200, and 250 degrees C for 2 h are 378, 402, 445, and 469 F/g, respectively, which indicate an increase with increasing annealing temperature. During stability tests, the as-grown MnOx-MWCNTs nanocomposite electrode can preserve 80% of its original capacitance after 6000 cycles of operation which can be increased to 86% after annealing at 200 degrees C for 2 h. The EPD MnOx/MWCNTs coaxial nanocomposite pseudocapacitors with manganese oxide ionized by H+ ion process exhibit high specific capacitance, fast reaction rate, high stability, and have high potential for practical applications. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3601862] All rights reserved.