Nanocomposite electrodes for electrochemical supercapacitors

Abstract

<p>The electrochemical supercapacitors (ESs) are an emerging technology that promises to play an important role in meeting the demands of electronic devices and systems both now and in the future. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. Nanostructured manganese oxides in various forms have been found to be promising electrode materials for ES.</p> <p>Cathodic electrodeposition method has been developed for the fabrication of nanostructured manganese dioxide films. Manganese oxide films were obtained by galvanostatic, pulse and reverse pulse electrodeposition from KMnO₄ solutions. The diffusion-controlled deposition mechanism is based on the reduction of anionic MnO₄^- at the cathode surface. It was shown that film porosity is beneficial for the charge transfer during deposition, crack prevention in thick films and electrolyte diffusion in fabricated ES electrodes. The microstructure, chemical properties and charge storage properties of films prepared by different deposition methods are investigated and compared.</p> <p>Novel chemical precipitation methods have been developed to produce manganese dioxide and Ag-doped manganese dioxide nanoparticles. Composite electrodes for ES were fabricated by impregnation of slurries of the manganese dioxide nanoparticles and carbon black into porous nickel foam current collectors. The microstructure and chemical properties of the powders were characterized. The capacitive behaviour of the composite electrodes was studied.</p>