Sharif Digital Repository

Electric vehicles and electronics such as laptops and smartphones require an efficient amount of energy conversion and storage. As one of the reliable systems in this field, lithium-ion batteries have high energy density and lower emissions. Cathodic material is a bottleneck in the development of lithium-ion systems due to its high cost and limited energy capacity. In this study, lithium-rich oxide cathode was synthesized in the liquid phase using the co-precipitation synthesis method using six-aqueous nickel nitrate and four-aqueous manganese chloride precursors. The material was analyzed by structural characterization analysis as well as electrochemical characterizations. In this project,... 

Due to environmental concerns and continuous decrease in the price, photovoltaic (PV) generations have been increasing in the recent years. PV units can operate in grid-connected or islanded modes. In grid-connected mode, the PV unit delivers its generated power to the grid; on the other hand, in islanded mode, it supplies the local loads. In this research, a new decentralized power management and load sharing method for a photovoltaic based islanded microgrid consisting of various PV units, battery units and hybrid PV/battery units is proposed. Unlike the previous methods in the literature, there is no need to communication among the units and the proposed method is not limited to the... 

Batteries have always been used as one of the most important sources of electricity storage and supply. Among different types of batteries, lithium-ion batteries are widely used in various fields and engineering applications due to their high-density energy/power, high discharge/charge rate, and long life. The most common of these applications are using these batteries in all-electric and hybrid vehicles, which reduce environmental problems. Due to the high cost of these types of batteries and the environmental issues of battery decomposition, researchers are seeking to discover long-lasting batteries that lithium titanate oxide batteries have the most extended lifespan among lithium-ion... 

The usages of Autonomous Underwater Vehicles (AUV) are limited due to the lack of suitable portable energy sources. Researches show that chargeable batteries and fuel cells are the most appropriate energy source for AUVs in near future. The main purpose of thesis is the modeling and obtaining the governing equations for Aluminum/Air batteries containing seawater, the so-called semi fuel cell. The steady state governing equations include Navier-Stocks equations (Hydraulic-Boundary layer), chemical ionic species mass balance at boundary layer velocity field, electrochemical equations in the electrolyte and the electrode surface, equations of motion of the hydrogen bubbles and equations for the... 

Today, considering the global demand for reducing greenhouse gas emissions, rechargeable batteries are considered as a source of energy in electric vehicles, hybrid electric vehicles and smart grids. In all these applications for secondary batteries, the battery management system requires an accurate estimate state of charge of each cell. However, this estimate is difficult particularly for battery aging. In this study, a lithium-ion battery is modeled by using multidimensional multiphysics modeling and simulated in a comsol. In this simulation, the effect of the thermal conductivity coefficient on the battery temperature, initial salt concentration in electrolyte and the rate of discharge... 

Zinc-bromine redox flow batteries are promising for large-scale energy storage applications due to their high energy density and open-circuit voltage. Proposed models for predicting these batteries' performance are limited due to challenges such as zinc deposition during the charging step and the utilization of a complexing agent. In this study, a 2D dynamic model was developed to investigate the battery performance. The kinetic equations for half-reactions are considered according to their two-step electron transfer mechanism. The model predictions were validated against experimental data reported in the literature for different current densities. Afterward, effects of various operating... 

In Li-ion batteries, large volume changes of electrodes with high capacity, such as silicon electrodes during charging and discharging processes (insertion/extraction of lithium into/from the electrode), lead to restrictions on the use of this type of electrode. Given the very high capacity of silicon, predicting and modeling the behavior of silicon electrodes during electrochemical cycles is important and is also addressed in this thesis. First, using the theory of linear elasticity, relations are proposed that couple the diffusion of particles with small elastic deformation. The effect of hydrostatic stress on diffusion and stresses is investigated in lithiation processes. Then, the... 

Among the various materials, silicon anodes have the highest lithium absorption in lithium-ion batteries. But this high lithium absorption capacity can cause 300 percent volume expansion and large stresses. Experimental observations show that charge and discharge cycles may cause plastic deformation in some parts of the electrode particle. On the other hand, there is a possibility of a ratcheting phenomenon due to changing in elastic properties of the electrode material during the charging and discharging processes. However, this phenomenon has not been reported for silicon spherical electrode particles yet.This study aims to model the elastic-plastic behavior of silicon spherical electrode... 

The use of electric vehicles is increasing day by day due to the reduction of pollution, reduction of fuel costs, higher efficiency, etc. Increasing the distance traveled in each charging period of the electric vehicle battery pack and increasing the lifetime of the battery cells are the most important challenges facing the electric vehicle industry. In electric vehicles, Li-Ion battery cells are used to store energy, so to improve these challenges, we first need to carefully examine the behavior of these cells with the various conditions that occur during operation to design other circuits such as balancing circuits, Battery management system, etc. In this thesis, first a model is proposed... 

Using energy storage systems has been remarkably improved the energy systems efficiency and reliability indicators of the system and also reduced the operating costs of these systems. Thus using them in an energy system would count as an advantage. Lately, the procedure of implementation of these systems has been studied widely and various motives behind implementing them have been reviewed. For example, the effect of cost optimization in electrical vehicles on reliability indicators from the load management perspective can be addressed. Therefore this thesis has studied the effect of electrical and thermal storage systems on the reliability indicators of an energy hub and the effect of... 

One of the main challenges in managing flow batteries usage is estimating their state of charge. Since The concentration of ions in the battery indicates the battery's charge and, on the other hand, the sensors for measuring the concentration are expensive, observers should be used to estimate the concentrations of the ions in the battery. This work is done by measuring the cell voltage, and finally, using the mathematical model of the battery, the amount of concentrations and state of charge is calculated. In this work, a vanadium flow battery was initially modeled accurately and mechanistically using COMSOL software to replace an actual flow battery in subsequent studies. Also, two... 

In regard to the benefits of solar energy such as endlessness and pureness, design and implementation of a convertor for absorbing energy from solar cells is of interest. Thus, a suitable convertor with acceptable efficiency is designed to charge the batteries. In order to increase the efficiency and to decrease the electromagnetic interference, a novel method is proposed for soft switching. Due to the nonlinear behavior of solar cells and also variations of their input energy with respect to the change of solar emission and temperature, two controllers - one for maximum power point tracking from solar cells and the other to appropriately charge the 48-volt batteries - are designed.... 

To ensure stable and optimal operation of lithium-ion batteries (LIBs), it is necessary to use a management system for online monitoring and accurate estimation of battery State of Charge (SOC). Due to LIBs' complex dynamics and effective factors such as temperature and side reactions, battery SOC estimation has become one of the greatest challenges for experts in the field. In this research, an adaptive sliding mode observer has been designed and evaluated for a cylindrical lithium manganese oxide battery with a capacity of 1258 mAh. At first, rigorous simulation of lithium-ion battery has been performed by utilizing the P2D electrochemical as well as thermal and aging model to be the main... 

In Li batteries, lithium ions are exchanged between two electrodes, along with the accompaning electron transfer to maintain riability good ionic conductivities and electrolytes stability are achived through additives to the electrolyte. Such matrial should possess good anions acceptability. This work investigates the potential of aza-ethers in this regard. The softness criteris is basically employed. DFT calculation for selected molecules of different size, substituents and interacting atoms are used to correlate softness, electrophilicity, Fukui no, etc to the usefulness of the corresponding matrials  

Focusing on fossil fuel to secure energy demand lead to big challenges. Hydrogen as alternative for fossil fuel has attracted a lot of attentions. Fuel cell with an electrochemical reaction which it’s byproducts are water and heat convert Hydrogen into electricity. High efficiency and low environmental pollution, persuade many researchers toward fuel cell commercialization. But problems such as high cost, high power oscillation and inertia, avoid fuel cell from significant development. One way to deal with these problems is using the fuel cell and battery hybrid system. In recent decade too many research has been made in utilizing this hybrid system in transportation. This project... 

Nuclear batteries have been attractive since the beginning of the twentieth century due to their longer life in comparison with other types of batteries. These batteries are produced in different types with different efficiencies depending on the method used to convert their energy. In this study, due to the lack of the resources in the country to study the types of nuclear batteries, first we did an overview of the classification and operation of different types of nuclear batteries, especially on the latest type of nuclear batteries, PIDEC, that has not been studied in the country so far. The most important feature of a PIDEC is that it has an intermediate stage to transmit the maximum... 

Lithium ion battery is one of the innovative and emerging technologies in energy sector that has played a major role in electricity supply security by integration of renewable energy technologies in electrical grid, implementation of electrical transportation system and de-carbonation of the both sectors in recent years. On the other hand, the formation of the potential market of technology as one of the functions of the technological innovation system plays an essential role in creation and advancement of innovation in the energy sector. Therefore, in this thesis, the development of lithium ion battery technology in Iran has been investigated from the perspective of the technology market in... 

Although much progress has been made in eliminating, conserving, and reducing migration and emissions of radioactive materials, the risk of radioactive material release into the environment is still one of the most important hazards in the use of nuclear energy. In this study, graphene compounds have been used as adsorbents for the removal of radioactive materials due to their high level, cost-effectiveness and simplicity of the synthesis process of various composites. In this regard, the removal of strontium and cobalt by graphene compounds has been investigated. Magnetite nanoparticles were anchored on the surface of graphene by sol-gel method and adsorption in batch mode was investigated.... 

Li7La3Zr2O12 (LLZO) solid-state electrolyte is a very promising electrolyte for a variety of ion lithium solid-state batteries, due to high conductivity of Li ions at room temperature as well as its chemical stability with Li metal anode. LLZO phase has two tetragonal and cubic symmetries. The conductivity of the cubic phase is two times higher than that for the tetragonal phase. To stabilize the cubic phase at room temperature, 0.2, 0.25, and 0.3 mol% Aluminum was doped to LLZO solid-state electrolyte. This powder was synthesized by sol-gel combustion method at 1000˚C. The cubic phase and lack of impurity of the samples doped with 0.25 and 0.3% Aluminum were determined by X-ray Diffraction... 

Titanium nitride-carbon nanocomposites are synthesized by the reaction of TiCl4 and NaN3 in supercritical benzene medium that also serves as a carbon source. In order to improve the crystallinity of the as-prepared precursor (SI), it is further heat-treated at 1000 ˚C for 3-10 h using anhydrous ammonia and UHP nitrogen atmospheres at 1000 ˚C (SIII-SV). Moreover, to improve electrochemical behavior, the synthesized nanocomposite (SIV) is modified with Pt nanoparticles using a polyol process. For better understanding of synthesized catalyst nature and justifying their variant ORR activity several analyses are done. X-ray diffraction (XRD), Raman spectrum, field emission scanning electron...