Master Degree / Yüksek Lisans Tezleri

Permanent URI for this collectionhttps://hdl.handle.net/11147/3008

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  • Master Thesis
    Development of a Novel Low-Pressure Nanofiltration Membrane for Li+ Mg2+ Separation
    (2023) Aslıyüce, İsmail Tunahan; Altınkaya, Sacide Alsoy
    Lithium-based batteries stand out as a crucial technology for energy storage. Between 2020 and 2022, lithium production surged from 77,000 to 100,000 tons. The majority of the world's lithium reserves are situated in water resources. Nevertheless, the direct extraction of lithium requires additional chemical processes due to the presence of other salts. Nanofiltration is recommended as an environmentally friendly and economical method for lithium purification. The main objective of this thesis is to develop a nanofiltration membrane for efficient Li+ and Mg2+ separation. The support membrane was prepared through the phase inversion technique using polyamide-imide (PAI) in the casting solution and polyethyleneimine in the coagulation bath. In-situ dopamine polymerization under oxygen backflow formed an intermediate layer on the support surface for further modification. PDA-modified support was first coated with polyethyleneimine (PEI) functionalized alumina particles and then low molecular weight PEI (800Da). The final membrane design was optimized for Li+ purity and Li+ recovery. The produced nanofiltration membrane exhibited significant rejection rates, notably around ~90% % for Mg2+ and approximately ~ -21% for Li+. Additionally, it demonstrated a pure water permeability of 9.7 L/m2hbar. Each membrane layer underwent characterization through various techniques, including SEM, EDX, zeta potential analysis, AFM, and contact angle measurements. The membrane was subjected to stability tests under dynamic and static conditions. Li+ and Mg+2 rejections, separation factor, and salt solution flux did not change after 30 days of storage in 2000 ppm salt solution and during 72 h dynamic filtration test.
  • Master Thesis
    Numerical and Experimental Investigation of an Electric Vehicle Battery Module Thermal Management System
    (Izmir Institute of Technology, 2022) Gediksiz, Çağlar; Çetkin, Erdal
    Today, electric vehicles play an essential role in preventing pollution from fossil sources. Therefore, it is vital to develop battery technology in electric vehicles. The biggest problem experienced is the thermal runaways, which is a phenomenon that may cause burning and explosions following the decrease in battery capacities. The thermal runaway problem can be solved by using the thermal management system to keep the temperature range under control. In this study, a 6.7 kWh battery pack was produced. Battery pack operation consists of two parts, mechanical and thermal. In the mechanical part, battery pack assembly and drop tests, one of the mechanical tests, were carried out. At the end of the battery pack assembly, voltage measurements were made, and the accuracy of the assembly was demonstrated. Besides, a numerical and experimental study supported drop tests. As a result of this study, the battery case did not show permanent deformation (2.529x 108 N/m2) as suggested in the numerical experiments (1.263x 108 N/m2). Discharge characteristics and battery module model were discussed in the thermal management part. The information in the literature confirmed the discharge characteristic. The gap between the battery cells reached its most efficient value at 8 mm. In the developed battery module, thermal management was attempted using a heat plate and a cooling pipe. According to the numerical results, the battery module reaches 311.37K at 10C discharge. In the experimental process, the battery pack was charged with 15 amps and discharged with 30 amps. Moreover, the temperature values reached a maximum of 31 degrees. In the experiment on electric vehicles, a maximum discharge level of 255 A was observed. In this experiment, the battery pack reached a maximum of 36 degrees.
  • Master Thesis
    Lithium Extraction From Geothermal Brine by Adsorption Method With Electrolytic Y-Mno2 Sorbent
    (Izmir Institute of Technology, 2022) Toprak, Seyra; Demir, Mustafa Muammer; Baba, Alper
    In recent years, studies on the recovery of lithium metal have attracted great attention due to its wide application areas, especially in lithium-ion batteries. Recovery of lithium from brines is preferred considering the environmental impacts in mining. The application of manganese oxide sorbents to recover lithium from geothermal brines has been extensively studied as it is a potential source of lithium. In this thesis, adsorption was performed in Tuzla Geothermal Power Plant (TGPP) at 87 °C and 2 bar using a mini-pilot system in the reactor near the reinjection well of the plant to investigate the adsorption performance in field conditions. As a new approach, electrolytic manganese dioxide (γ-MnO2), which is widely used as cathode material in batteries, was used as the sorbent material for lithium and its adsorption/desorption performance was investigated. Batch adsorption experiments were performed in synthetic lithium solution and the optimum working conditions were determined as pH 12, adsorbent concentration of 3 g/L, and initial lithium-ion concentration of 200 mg/L. The highest adsorption capacity of the sorbent in the Langmuir model was found as 9.74 mg/g. The maximum adsorption performance was obtained at 1h adsorption in Tuzla GPP. In the continuation of the study, desorption was carried out in acidic medium with the brine-treated sorbent. Lithium concentration was enriched to around 250 ppm with repetitive desorption studies. Reusability of the sorbent was investigated and the reused sorbent showed almost 40% performance compared to virgin powder. γ-MnO2 was found as a promising sorbent for the separation of lithium from geothermal brines.
  • Master Thesis
    Synthesis and Characterization of High Nickel Content Cathode Materials for High Performance and Capacity Reach in Li-Ion Batteries
    (Izmir Institute of Technology, 2022) Uğur, Turgut; Karabudak, Engin
    Due to their high energy density, low self-discharge properties, nearly negligible memory effect, high open-circuit voltage, and extended service life, lithium-ion batteries continue to gain interest as a promising energy storage technology. In the automotive industry, high-energy lithium-ion batteries have become the preferred power source for electric vehicles and hybrid electric vehicles in recent years. With the development of lithium-ion battery technology, several materials have been used into the cathodes and anodes in order to improve performance. LiNiCoAlO4, LiMn2O4, LiNiMnCoO4, Li4Ti5O12 and LiFePO4are five lithium-ion batteries that are commonly utilized in commercial EVs today. NMC cathode material is one of the most effective lithium-ion battery materials for balancing specific qualities. The battery cathode of NMC is strengthened with a specific ratio of three synthetic components (Nickel, Manganese and Cobalt). Depending on the proportions of these three chemical constituents, battery performance can vary. Synthesis, characterisation, and electrochemical studies of cathode materials with a high Nickel content were performed in this project in an effort to boost the specific capacity and durability of Li-ion batteries. In these preliminary studies, the synthesis and characterization of Ni(OH)2 structures, which serve as a starting material for the synthesis of cathode materials with a high Nickel content, was also a goal. In the research, the spherical Ni(OH)2 structure was effectively synthesized, and excellent electrochemical results were achieved. SEM and XRD analyses were performed on the resulting products.
  • Master Thesis
    Synthesis and Characterization of Aluminum Doped To Extend Cathode Life in Li-Ion Batteries
    (01. Izmir Institute of Technology, 2021) Tekin, Onur; Karabudak, Engin
    Lithium-ion batteries have an important place in meeting the energy needs and are of greater importance than their cognates, thanks to their characteristics as secondary batteries. Volumetric and gravimetric energy densities are the main features that carry lithium-ion batteries to the top. Lithium-ion batteries consist of different parts: cathode, anode, separator and electrolyte. While the anode materials are generally based on silicon, carbon and tin, the cathode materials include layered LiCoO2, spinel LiMn2O4, olivine LiFePO4, layered LiNi0,8Co0,15Al0,05O2(NCA) and layered LiNiCoMnO2 (NMC). Nmc and nca cathode materials stand out due to their high energy densities. Of course, lithium-ion batteries also have some disadvantages. A prime example of this is the capacity reductions it experiences with the increasing number of cycles. The main reasons for the decrease in capacity are; The transformation of the layered structure into spinel structure, the contamination of the Lio structure on the cathode to the electrolyte structure as a result of the side reactions that occur, damage the stable structure of the electrolyte and lead to Li loss. Metal oxide surface modification methods come to the fore in studies conducted to prevent these disadvantages. In this study, nmc structure was synthesized by reprecipitation method. Xrd, and sem analyzes of the obtained structure were taken. Al2O3 surface modification method was applied on the cathode surface. Cyclic voltammetry analyzes of the nmc structures with and without the modification applied were made with the help of potentiometry and the results were compared.