Development of Flexible SWCNT based Supercapacitors through Electrohydrodynamic Atomization Technique

Abstract

Development of energy storage technologies has become immensely vital for the efficient consumption of energy and reliable utilization of renewable energy as the conventional energy resources pose serious challenges to human health, environment and energy security. Exponential growth of power production through renewable resources like solar, wind, and tidal power to replace enervating fossil fuel has called for implementing environment-friendly, sustainable energy conversion and storage systems. Miniaturized, portable, flexible electronic products demand for the development of new, flexible, lightweight, low-cost and environmentally friendly energy storage devices.With a short cycle life and low power density, rechargeable batteries cannot meet the increasing cycle stability and power demands of the electronic devices. In order to address these issues, energy storage devices with high energy density, flexible design and long lifetime have attracted tremendous research interest. Supercapacitors have been the object of important research in the last decade as they have the potential to provide higher energy density than dielectric capacitors and higher power density than batteries. A wide range of materials and processes have been studied thus far to develop supercapacitors to meet the current and future demands. In this dissertation, electrohydrodynamic atomization (EHDA) technique has been adopted to fabricate nanostructured functional thin films for applications in supercapacitors. EHDA technique is one of the fast emerging, advanced fabrication technique in the field of printed electronics. This cost-effective, room temperature technique has the potential to process organic, inorganic and polymeric materials. With the ever growing need for high performance hybrid/composite thin films, EHDA technique promises to meet the aforementioned goals easily compared to conventional technique. Initially, nanostructured ITO have been thin films been deposited through EHDA technique on flexible substrates for transparent current collector applications. The precursor was prepared by the by dispersing the nanoparticles in combination of solvents. Optimization of the process parameters to achieve the crucial Taylor cone is explained. The optical, morphological and electrical studies conducted on the deposited ITO layers have been discussed. After the deposition of transparent current collectors on flexible substrates, active layers of flexible single walled carbon nanotube (SWCNT) thin films have been fabricated on flexible substrates. The water based precursor has been modified with a combination of solvents in order to lower the surface tension and make it suitable for the EHDA process. The purity, surface morphology, chemical composition, electrical and electrochemical characteristics of the deposited SWCNT electrodes have been studied and discussed.