Solid state planar micro supercapacitors materials interfaces state of art electrode design and self powered device

Abstract

The demand for miniaturization of energy storage systems has accelerated the development of on-chip micro-power devices for integration into portable electronic devices. Micro-supercapacitors can suitably cater to the need by functioning as efficient miniaturized energy storage devices with high power density, fast charge-discharge rates and long cyclic lifetime. The electrode material and its design are two dominant factors affecting the performance of a micro-supercapacitor. The thesis work focuses on fabrication of solid-state micro-supercapacitors using electrode design and material as the parameters to enhance the performance. The interfaces of materials were designed to attain pseudocapacitive properties for high electrochemical performance. Further, the strength of the electric field was improved through the rational design of electrodes utilized for the fabrication of micro-supercapacitors. Solid-state micro-supercapacitor is presented with a planar sharp edge concentric circular geometry of gold electrode coated on a glass substrate and pseudocapacitive material for the charge storage. A few metal oxides and metal dichalcogenides such as ruthenium dioxide, manganese oxide (MnO), molybdenum disulphide (MoS2) are known to exhibit capacitive response similar to the carbon materials through a phenomena called pseudocapacitance. Thesis work uses key pseudocapacitive materials like iron (III) oxide (Fe2O3), MnO, and MoS2 in a matrix of electrically conducting carbon foam (CF) for solid-state micro-supercapacitor. Fe2O3 nanoparticles were directly synthesized on the walls of a three-dimensional (3D) CF matrix for high surface (209 m2/g) and enhanced pseudocapacitance. A systematic optimization was performed to achieve an optimal ratio of CF and Fe2O3 for a maximum enhancement of ~48% in charge storage capacity in a three-electrode electrochemical measurement. Polyvinyl alcohol phosphoric acid was used solid and transparent electrolyte. The modified electrode design with ~23% larger perimeter and higher elec...