Sharif Digital Repository

In the first part of this research, for the first time, we introduced a flexible high performance graphene-based supercapacitor using silver fiber fabric as the current collector. The silver fiber fabric offers remarkable advantages such as light weight, mechanical flexibility and ease of integration with electronic textiles, which well-suited for wearable energy storage devices. A new hybrid material of graphene-silver fiber fabric (rGO/SFF) was prepared through a facile electrophoretic deposition of graphene and being used as a binder-free flexible supercapacitor electrode. In order to obtain the optimum condition, the effect of deposition time was investigated and a duration time of 10... 

In this research, metal oxides and hydroxides with carbon materials and conductive polymers (CPs), as well as transition metal oxysulfide nanostructures (TMOS), hybrid of Tin oxide and sulfie and polyphasphate-reduced graphene oxide (PPO-RGO) have been used as an active electrode materials for supercapacitors. In the first section of thesis, Tiron and graphene oxide (GO) were used as an anionic dopants to increase the capacity and stability of polypyrrole (PPy). In order to increase the capacity of Tiron/PPy/GO nanocomposite, vanadium oxide (V2O5) was used. The Tiron/PPy/GO/V2O5 nanocomposite was deposited on a stainless steel (SS) as a substrate via one-step electrochemical deposition... 

Development of renewable energy production from sun and wind and the development of hybrid electric vehicles seem to be integral components in modern societies in order to overcome the environmental pollution and reduce the use of fossil fuel sources. In such devices energy storage plays an important role and supercapacitor is one the important energy storage devices. Structure of supercapacitor electrodes has considerable effect on supercapacitor performance. Graphene as a 2D carbon structure can improve electrochemical properties of electrodes. Here three different hybrid structure of graphene have been realized. The high capacitance and cyclic stability of graphene nanosheets decorated... 

Titanium carbide MXene (Ti_3 C_2 T_x) has attracted significant research interest because of its extraordinary advantages as advanced electrode material for energy storage. In this study, 4-aminodiphenylamine functionalized Ti_3 C_2 T_x/polyaniline composite synthesized by in situ growth of PANI on 4-aminodiphenylamine functionalized Ti_3 C_2 T_x nanosheets. First, Ti_3 C_2 T_x MXene nanosheets was prepared according to the minimally intensive layer delamination (MILD) method followed by sonication. Ti_3 C_2 T_x nanosheets were modified with 4-aminodiphenylamine diazonium salt. The FTIR، FE-SEM and EDS analysis were used to characterize modified Ti_3 C_2 T_x. Finally, the Ti_3 C_2 T_x... 

Supercapacitors are safe and environmentally friendly energy storage devices that have been considered for their diverse applications. One of the most important factors that control supercapacitors' capacity is the electrode material's structure and properties. Adding heteroatoms or composite materials synthesis is one way to improve electrode performance. In this study, a facile, fast, and economical hydrothermal method was used to synthesize N doped, P doped or N/P co-doped 3D reduced graphene oxide (rGO) for high-performance supercapacitor application. Nitrogen and phosphorus elements were replaced by carbon atoms simultaneously during the graphene oxide hydrothermal reduction procedure.... 

Energy conversion and storage as well as life sciences are among the areas of our daily life. Interest in carbon nanomaterials for energy storage systems such as supercapacitors has enormously risen due to their attractive electrical conductivity, chemical inertness, and charge storage capacity. Producing these nanomaterials with a simple, scalable, and cost-effective method is the major problem for commercializing them. The reduction of graphitic oxide is a versatile procedure to prepare 3D graphene. Despite many green methods, the dynamics behind ultrafast thermal graphitization have remained elusive. Here, we demonstrate an effort to understand the graphitization mechanism of graphitic... 

Energy conversion and storage as well as life sciences are among the areas of our daily life. Interest in carbon nanomaterials for energy storage systems such as supercapacitors has enormously risen due to their attractive electrical conductivity, chemical inertness, and charge storage capacity. Producing these nanomaterials with a simple, scalable, and cost-effective method is the major problem for commercializing them. The reduction of graphitic oxide is a versatile procedure to prepare 3D graphene. Despite many green methods, the dynamics behind ultrafast thermal graphitization have remained elusive. Here, we demonstrate an effort to understand the graphitization mechanism of graphitic... 

The search for sustainable and clean energy sources to replace fossil fuels has become one of the most important scientific and technological challenges today due to the threat of fossil fuel shortages and environmental pollution. Therefore, the need for clean energy production and storage resources, including supercapacitors, has increased day by day. Today, supercapacitors have been considered suitable for energy storage due to their high-power density, appropriate energy density, long cycle life, and high safety. The aim of the present study was to obtain activated carbon fabric as electrode material in electrochemical energy storage applications and specifically supercapacitors. The... 

Transition metal oxides and carbon based materials (especially graphene) are common electrode materials in supercapacitors. The metal oxide limitation is due to their high agglomeration and low electrical conductivity. On the other hand graphene base materials due to their unique structure as well as high electrical conductivity and high surface area increase energy storage capability. However, chemically produced graphene generally suffers from high agglomeration and re-stacking after removal from the solution and drying, g, which results in reduced electrochemical performance of graphene sheets in supercapacitors. To take full advantage of these two groups of materials, it is expected that... 

In this thesis, the improving effects of TiO2 nanotubes (TiO2NTs) fabricated by anodizing of titanium as suitable substrate for deposition active materiales in supercapacitors were considered. PANI/Pd/TiO2NTs electrodes with highly porous structures and good capacitive characteristics were prepared by electrodeposition of polyaniline on palladium nanoparticles loaded TiO2 nanotubes. The results illustrated that the specific capacitance of these electrodes was around 1060 Fg−1 in 1.0 M H2SO4 electrolyte as measured at a constant current of 2.0 Ag−1, whereas it was 210 Fg−1 for the PANI/TiO2NTs electrode. NiO-ZnO/TiO2NTs electrodes were synthesized by the electrodeposition of... 

Electrochemical supercapacitors are the charge-storage devices having high power density.The materials in the nano-size form with high surface area and high porosity give the best performances as the electrode materials for supercapacitors because of their distinctive characteristics of conducting pathways, and nanoscale dimensions. Therefore, the synthesis and the capacitive characterization of the high surface area nanomaterials such as nanotubes, nanowires,etc, have been carried out extensively in the past few years. In this research Polyaniline nanowires were electrochemically deposited on stainless steel electrode with the technique of Choronoamperometry and pulse Voltammetry and... 

High-capacity electrode materials are crucial for enhancing the performance of supercapacitors. Transition metal sulfides are considered promising materials for supercapacitor applications due to their high theoretical capacity and good electrical conductivity. Additionally, cerium oxide improves the performance of supercapacitors due to stable reversible oxidation states and greatly supported the faradaic redox reaction. In this study, ceria nanosheets incorporated with MCoS (M=Mn, Zn, Cu) were synthesized successfully through a facile hydrothermal method by sulfidation of MCo LDH/CeO2. The structural and morphological characteristics were analyzed using X-ray diffraction, scanning electron... 

Today, supercapacitors are an inseparable component of electronic devices such as hybrid cars, telecommunication equipment, and personal electronic devices, and this device is also used to store clean energy. In this research, polyacrylic acid hydrogel was first synthesized to be used as a supercapacitor electrode and polyaniline was used as an electrically conductive polymer in its structure to improve the electrical properties of this hydrogel. To achieve this structure, the previously synthesized polyacrylic acid hydrogel was immersed in a solution of aniline monomer and other components necessary for the aniline polymerization reaction, and after the soaking process was completed, the... 

Supercapacitors are one of the most important energy storage devices that have been researched with respect to the development of hybrid cars. Polymer composites have received much attention due to the electrochemical properties of conductive polymers and the synergistic effects of the composite components. In the present Thesis, in order to investigate the synergistic effect of gold nanoparticles with MnO2 nanorods as a metal oxide and polyaniline as a conductive polymer and graphene as a carbon material, two groups of composites were synthesized in the presence and absence of graphene. Characterization of the electrode material is carried out by XRD, FT-IR and FE-SEM tests. The... 

In the urban railway transportation system, large amount of power is consumed for starting the movement and acceleration. A great part of this energy is transformed to the train kinetic energy which in the case of break is reduced to zero. Thus recovering of train kinetic energy during the brake can help to reduce train energy consumption. One of the possible ways is using energy storage during the brake and using it again during acceleration. Storage can be performed in three kinds, fixed, mobile and hybrid. In this thesis, super capacitors have been investigated as fixed and mobile storages. After reviewing electrical railway transportation systems, elements of these systems have been... 

In urban rail transport systems such as subway, Trains are constantly accelerate and brake, so the braking system is of great importance in energy consumption and constitute about 30 to 40 percent of total energy consumption trains, thus retrieval braking energy will lead to significant savings in urban rail transport systems. In this paper, in the beginning, different storage equipments for storage braking energy have been studied and compared and finally Supercapacitors due to technical and economic features have been selected for the storge of equipment. These systems can be implemented in both stationary and onboard. For precise evaluation and select the appropriate storage system, by... 

Given the high rate of energy dissipation in electric urban rail lines, methods of saving energy in these systems have become a topic of interest. The use of energy saving equipment to save the energy wasted in braking (Because of the diode rectifier, thermal energy is usually wasted and is not reversible) can play an important role in reducing the energy loss. The role of energy storage equipment, from other aspects such as voltage regulation and increasing the system reliability is also remarkable. In this thesis, the various possible methods for saving energy in the Metro system are expressed.
The various types of storage devices with increased reuse of braking energy which is the... 

Nowdays, distributed generation (DG) systems based on renewable energy sources have significantly increased around the world as an alternative solution to enhance the power quality and reliability and reduce the need for extensive transmission system as well. An evolved recent concept called microgrid is developed by grouping a cluster of loads and DG units in a common local area which increases the integaration of sustainable energy generation systems. This thesis presents control of a medium voltage (MV) microgrid considering multi-hybrid distributed generation systems (MHGS) and renewable energy resources in island mode. The first part is focused on the development a control strategy for... 

In recent years, MXenes, a class of 2D materials, have drawn significant interest because of their special properties and layered structures. Among the MXenes family, Ti3C2 is a promising candidate in energy storage field due to its unique electrical conductivity, hydrophilicity, surface redox reactions, excellent packing density and high volumetric capacitance. In this thesis, synthesis and supercapacitor application of Ti3C2 have been investigated. HCl and LiF solution and mild exfoliation method has been used for etching Al layers from Ti3AlC2 and MXene synthesis. To analyze the structure of this material, scanning electron microscopy, atomic force microscopy, X-ray diffraction... 

Recently, Supercapacitors, as one of the most important energy storage devices, have attracted attensions by the scientists. Supercapcitor devices with appoporate design can store energy by two different mechanisms: i) physical (like conventional capacitors, i.e. by using polarization of the electrolyte, and ii) formation of electric double layer) and chemical mechanisms (like batteries, with reversible faradic reactions). These energy storage mechanisms allow these devices not only store high energy density but also they can provide high power density. In this project, two Co3O4/Co(OH)2 and Co3O4@Sponge-like rGO electrodes are made with chemical and electrochemical methods. To characterize...