Loading...
Search for: lithium
0.013 seconds
Total 202 records

    Highly regioselective, base-catalyzed, biginelli-type reaction of aldehyde, phenylacetone and urea/thiourea kinetic vs. thermodynamic control

    , Article Journal of Sulfur Chemistry ; Volume 39, Issue 2 , 2018 , Pages 151-163 ; 17415993 (ISSN) Nematpour, M ; Rezaee, E ; Jahani, M ; Tabatabai, A ; Sharif University of Technology
    Taylor and Francis Ltd  2018
    Abstract
    An efficient one-pot regioselective synthesis of various novel 3,4-dihydropyrimidin-2(1H)-one (DHPMs) via a three-component Biginelli-type condensation of aldehyde, phenylacetone and urea/thiourea under two different based-catalyzed conditions is described. In kinetic control path, lithium N, N-diisopropylamide (LDA-20 mol % generated in situ from n-BuLi and diisopropylamine) was used as the base, in tetrahydroforane (THF) as the solvent at 0°C. Thermodynamic control path was run with NaH as the base, in EtOH as the solvent under reflux status. The simple procedure, mild base-catalytic reaction conditions, no column chromatography and good to high yields are important features of this... 

    The effect of Li on the tensile properties of cast Al-Mg2Si metal matrix composite

    , Article Materials Science and Engineering A ; Volume 490, Issue 1-2 , 2008 , Pages 250-257 ; 09215093 (ISSN) Hadian, R ; Emamy, M ; Varahram, N ; Nemati, N ; Sharif University of Technology
    2008
    Abstract
    The effects of both Li modification and cooling rate on the microstructure and tensile properties of an in situ prepared Al-15%Mg2Si composite were investigated. It was found that the addition of 0.3%Li reduces the average size of Mg2Si primary particles from ∼30 to ∼6 μm. The effect of cooling rate was investigated by the use of a mold with different section test bars. The results showed an increase in both UTS and elongation values with reduction in section thicknesses corresponding to increasing cooling rates. Adding Li also raised the tensile strength and elongation values and reduced the number of decohered particles observed in fracture surfaces thereby increasing the alloy's... 

    Sodium borohydride-solid LiClO4: An effective reagent for reducing aldehydes and ketones in aprotic solvent

    , Article Synthetic Communications ; Volume 35, Issue 17 , 2005 , Pages 2271-2276 ; 00397911 (ISSN) Halimjani, A. Z ; Saidi, M. R ; Sharif University of Technology
    2005
    Abstract
    An efficient and simple method for the reduction of aldehydes, ketones and acid chlorides has been accomplished by using NaBH4-solid LiClO 4 in mild conditions at ambient temperature with complete chemoselectivity in reduction of α,β-unsaturated aldehydes and ketones. The reaction is fast with high yield and simple workup. Copyright © Taylor & Francis, Inc  

    Advanced gel polymer electrolyte for lithium-ion polymer batteries

    , Article ASME 2013 7th Int. Conf. on Energy Sustainability Collocated with the ASME 2013 Heat Transfer Summer Conf. and the ASME 2013 11th Int. Conf. on Fuel Cell Science, Engineering and Technology ; July , 2013 ; 9780791855515 (ISBN) Zhang, R ; Hashemi, N ; Ashuri, M ; Montazami, R ; Advanced Energy Systems Division, Solar Energy Division ; Sharif University of Technology
    2013
    Abstract
    We report improved performance of Li-ion polymer batteries through advanced gel polymer electrolytes (GPEs). Compared to solid and liquid electrolytes, GPEs are advantageous as they can be fabricated in different shapes and geometries; also ionic properties are significantly superior to that of solid and liquid electrolytes. We have synthetized GPE in form of membranes by trapping ethylene carbonate and propylene carbonate in a composite of polyvinylidene fluoride and N-methylpyrrolidinore. By applying phase-transfer method, we synthetized membranes with micro-pores, which led to higher ionic conductivity. The proposed membrane is to be modified further to have higher capacity, stronger... 

    Properties, crystallization mechanism and microstructure of lithium disilicate glass-ceramic

    , Article Journal of Non-Crystalline Solids ; Volume 356, Issue 4-5 , 2010 , Pages 208-214 ; 00223093 (ISSN) Goharian, P ; Nemati, A ; Shabanian, M ; Afshar, A ; Sharif University of Technology
    Abstract
    In this study, lithium disilicate glass-ceramic in the TiO2-ZrO2-Li2O-CaO-Al2O3-SiO2 system was investigated for dentistry applications by incorporation of P2O5 and Nb2O5 as nucleation agent. The influence of the particles size (nano and submicron size) and nucleating agents on the crystalline phases, microstructure, crystallization mechanism and mechanical properties were investigated. Our data indicated that in ceramic glass with nano and submicron P2O5, the main crystalline phase was lithium disilicate. The results also showed that change of P2O5 particle's size had significant effect on the crystalline phases and microstructure. By replacement of submicron P2O5 with submicron Nb2O5,... 

    Preparation of sulfur micro-particles suitable for lithium sulfur batteries using sulfur vapor deposition

    , Article Materials Research Express ; Volume 6, Issue 10 , 2019 ; 20531591 (ISSN) Hakimi, M ; Borzabadi Farahani, A ; Sanaee, Z ; Ghasemi, S ; Mohajerzadeh, S ; Sharif University of Technology
    Institute of Physics Publishing  2019
    Abstract
    The current paper reports the deposition of sulfur micro-particles using sulfur vapor deposition (SVD). Sulfur particles in size of 5 to 45 μm were deposited on a stainless steel substrate to be used as the cathode with porous structure in lithium sulfur (Li-S) batteries. Mass loading of about 0.5 mg cm-2 was obtained from this pure sulfur cathode. The structure of this binder-free cathode was characterized by field emission scanning electron microscopy (FESEM), x-ray spectroscopy (EDS), and x-ray diffraction (XRD). The electrochemical performance of the battery with two different organic liquid ether- and carbonate-based electrolytes was investigated and the results demonstrated that the... 

    Solid lithium perchlorate as a powerful catalyst for the synthesis of β-aminoalcohols under solvent-free conditions

    , Article Canadian Journal of Chemistry ; Volume 83, Issue 5 , 2005 , Pages 505-507 ; 00084042 (ISSN) Azizi, N ; Saidi, M. R ; Sharif University of Technology
    2005
    Abstract
    Lithium perchlorate catalyzed the ring opening of epoxides with amines to provide the corresponding β-aminoalcohols in excellent yields with high regioselectivity. The reaction proceeds rapidly under mild and neutral conditions and worked well with primary, secondary, aliphatic, aromatic, and hindered amines in short times at room temperature, in the absence of solvent. © 2005 NRC Canada  

    Mechanism understanding of Li-ion separation using a perovskite-based membrane

    , Article Membranes ; Volume 12, Issue 11 , 2022 ; 20770375 (ISSN) Golmohammadi, M ; Habibi, M ; Rezvantalab, S ; Mehdizadeh Chellehbari, Y ; Maleki, R ; Razmjou, A ; Sharif University of Technology
    MDPI  2022
    Abstract
    Lithium ions play a crucial role in the energy storage industry. Finding suitable lithium-ion-conductive membranes is one of the important issues of energy storage studies. Hence, a perovskite-based membrane, Lithium Lanthanum Titanate (LLTO), was innovatively implemented in the presence and absence of solvents to precisely understand the mechanism of lithium ion separation. The ion-selective membrane’s mechanism and the perovskite-based membrane’s efficiency were investigated using Molecular Dynamic (MD) simulation. The results specified that the change in the ambient condition, pH, and temperature led to a shift in LLTO pore sizes. Based on the results, pH plays an undeniable role in... 

    Cycling performance of LiFePO4/graphite batteries and their degradation mechanism analysis via electrochemical and microscopic techniques

    , Article Ionics ; Volume 28, Issue 1 , 2022 , Pages 213-228 ; 09477047 (ISSN) Sharifi, H ; Mosallanejad, B ; Mohammadzad, M ; Hosseini Hosseinabad, S. M ; Ramakrishna, S ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2022
    Abstract
    In this work, cycling-induced aging occurring in 18650-type LiFePO4/graphite full cells at different C-rates is studied extensively. The mechanism of performance degradation is investigated using a combination of electrochemical and microstructural analyses. Half-cell studies are carried out after dismantling the full cells, using fresh and cycled LiFePO4 cathode and graphite anode to independently study them. The results show that the capacity of LiFePO4 electrodes is significantly recovered. The rate of capacity fading in the discharge state considered as irreversible capacity in the graphite is higher than LiFePO4 half cells, indicating a greater degradation in the performance of this... 

    Lithium Extraction with TiO2 Nanotube Synthesized by Anodizing Method

    , M.Sc. Thesis Sharif University of Technology Taghvaei, Nastaran (Author) ; Askari, Masoud (Supervisor)
    Abstract
    Due to the technology advancement and the large-scale application of lithium-ion batteries in recent years, the market demand for lithium is growing rapidly and the availability of land lithium resources is decreasing significantly. As such, the focus of lithium extraction technologies has shifted to water lithium resources involving salt-lake brines and sea water. The ion exchange process is a promising method for lithium extraction from brine and seawater having low concentrations of this element. Among various aqueous recovery technologies, the lithium ion-sieve (LIS) technology is considered the most promising one. This is because LISs are excellent adsorbents with high lithium uptake... 

    Thermal Behavior of Rechargeable Li-ion Batteries; Experimental Evaluations and Modeling

    , Ph.D. Dissertation Sharif University of Technology Shadman Rad, Mojtaba (Author) ; Baghalha, Morteza (Supervisor) ; Kazemeini, Mohammad (Co-Advisor)
    Abstract
    The main objective of this research is to experimentally evaluate thermal behavior of commercially available rechargeable Li-ion batteries based on minimum measurements on main battery parameters and then develop experimental based models to investigate their thermal behavior. Li-ion batteries with Graphit anodes and Li(Ni0.8¬Co0.15Al0.05)O2 cathodes will be used for this purpose. Voltage and temperature developments during cycling under various currents at controlled ambient temperatures are measured by battery tester. Measurements show that temperature evolutions demonstrate falls and rises at specific State-of-Charge (SoC) of the battery during cycling and therefore some heat consumers... 

    Study on Momentary and Overall Separation Factors in Lithium Isotopes Separation by Batch Electrolysis

    , M.Sc. Thesis Sharif University of Technology Azad, Mohsen (Author) ; Otukesh, Mohammad (Supervisor) ; Ahmadi, Javad (Supervisor) ; Kowsari, Mohammad Reza ($item.subfieldsMap.e)
    Abstract
    Lithium has two stable isotopes, 6Li and 7Li. Abundance of these isotopes are 7.53% and 92.43% respectively. Each isotope has an important role in nuclear industry. For example, 6Li compounds is used in production of tritium in nuclear fusion reactors coated with DT fuel and as fuel in nuclear fusion reactors that operate with laser inertial confinement method applied. 7LiOH is used to adjust the pH of the fluid coolant in light water reactors and also in Breeding Reactors. Lithium isotope separation in different ways so far been brought into operation. The other aspect to this work, it can be both continuous and batch for action. Lithium isotopes for the first time by electrolysis using... 

    Making Electrolyte Lithium Batteries Using Ionic Liquids and Organic Solvents

    , M.Sc. Thesis Sharif University of Technology Ranji, Hassan (Author) ; Gholami, Mohammad Reza (Supervisor)
    Abstract
    In this work, butyl methylimidazolium tetrafluoroborate and butyl methylimidazolium hexafluorophosphate are used as ionic liquid and lithium perchlorate and lithium hexafluorophosphate as lithium salt. Dimethyl carbonate and propylene carbonate are used as solvent to prepare diffrent kinds of organic - ionic liquids solvent for lithium ion batterries. In preliminary expriment it was distinguished that in the mixture of organic solvent lithium hexaflourophosphat has more conductivity in comparison with lithium perchlorate. There for,in this work, all organic-ionic liquid solvent electrolytes are considered based on lithium hexaflourophosphat salt. Different compositions of organic-ionic... 

    Influence of Cobalt and Vanadium Dopants on the Performance of TiO2(B) Nanowires used as anode Materials in Lithium-ion Batteries

    , M.Sc. Thesis Sharif University of Technology Amirsalehi, Mahmoud (Author) ; Askari, Masoud (Supervisor)
    Abstract
    Li-ion batteries have been widely applied as power sources for portable electronic devices. Recently, Li-ion batteries are considered as the most promising energy storage technology for electric vehicle applications however, fundamental improvements are needed. TiO2 (B) is attractive candidate for anodes in rechargeable Li-ion batteries, due to their low cost, non-toxicity and favorable channel structure for fast lithium mobility. It is predicted that synthesis of doped nanostructure of this material, through reducing the diffusion pathway and formation of crystal defects, will increase the capacity of TiO2(B). In this investigation, Co and V doped TiO2(B) nanowires are synthesized by... 

    Development of a Framework to Utilize Thermoelectrochemical-aging Battery Models in Optimal Design of Renewable Energy Systems

    , Ph.D. Dissertation Sharif University of Technology Astaneh, Majid (Author) ; Roshandel, Ramin (Supervisor)
    Abstract
    The operating conditions of the battery in renewable energy systems affect its electrochemical behavior and degradation process. Recent research mainly estimates battery lifetime through conventional methods such as counting the number of equivalent battery life cycles or based on simple experimental models that may lead to optimistic predictions in battery service period. In this study, a reduced-order thermoelectrochemical-aging battery model is developed for the application of renewable energy systems and the battery degradation analysis is investigated by this model. The proposed microscopic model evaluates the effect of battery operating conditions such as state of charge, current and... 

    The Effect of Nano-TiO2 and CaF2 Additives on Formulation and Properties of SiO2-Li2O Glass-Ceramics

    , M.Sc. Thesis Sharif University of Technology Gol, Saba (Author) ; Nemati, Ali (Supervisor)
    Abstract
    The goal of the present study is to analyze the effect of CaF2 and nano-TiO2 as additives on formulation and properties of common dental glass-ceramics. To achieve the goal, a glass system based on SiO2-Al2O3-Li2O-K2O-P2O5-ZnO-ZrO2 was considered to produce glass-ceramic samples and the additives, nano-TiO2 and CaF2, with the 0.5, 1, and 1.5 %Wt was added to the system. After the melting process, the glass samples poured in the water and ferrite was produced. In the next step, the ferrite was milled and pressed. In the heat treatment step, the samples were treated in the temperature range of 650-850°C in order to gain lithium disilicate glass-ceramics. In the last step, the chemical... 

    Preparation and Modification of Lithium-ion Battery Membrane/Separator

    , M.Sc. Thesis Sharif University of Technology Javadi, Omid (Author) ; Soltanieh, Mohammad (Supervisor) ; Mousavi, Abbas (Supervisor) ; Fathollahi, Abolfazl (Co-Supervisor)
    Abstract
    Electrolyte separator is the major component of lithium-ion batteries which the battery safety directly depends on it. In this work, a membrane separator based on the polyvinylidene fluoride (PVdF) was prepared via non-solvent induced phase separation (NIPS) method with water and ethanol as non-solvent and a mixture of dimethylformamide (DMF) and acetone as solvents. The effect of various acetone/DMF ratios and type of non-solvent on the structural, mechanical and electrochemical properties of separator was studied. The separator was characterized by FE-SEM, tensile strength, electrochemical AC-impedance spectroscopy, thermal stability and linear sweep voltammetry (LSV). Additionally, the... 

    Co-precipitation Synthesis Parameters of Lithium-rich Cathode Material

    , M.Sc. Thesis Sharif University of Technology Seraji, Pardis (Author) ; Sadrnezhaad, Khatiboleslam (Supervisor)
    Abstract
    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,... 

    Lithium Adsorption on TiO2 Ion-sieve from Magnesium Treated Brine Sources

    , M.Sc. Thesis Sharif University of Technology Naji Toosi, Alireza (Author) ; Asgari, Masoud (Supervisor)
    Abstract
    Brines are one of the main resources for lithium extraction and Iran has got many high magnesium and low lithium brine resources. In order to extract lithium, it is required to carefully identify these resources and their associated compounds and then an appropriate method can be adopted to extract lithium. Among the Previous researches, Bahadori, Jandaghi and Moazeni developed methods for removal of undesirable brines elements, Deposition of lithium from refined brine and lithium adsorption anatase ion-sieves membrane respectively; in this study it has been tried to investigate the optimization of the adsorption process, onto the TiO2-B ion sieve with nanotube morphology. TiO2-B nanotubes... 

    Production of Biodiesel from Vegetable Oils by Esterification Method Using Calcium Oxide as Base Catalyst

    , M.Sc. Thesis Sharif University of Technology Jalali Varnamkhasti, Roshanak (Author) ; Khorasheh, Farhad (Supervisor) ; Larimi, Afsaneh Sadat (Supervisor)
    Abstract
    The aim of this project is to fabricate and study heterogeneous CaO-based nanocatalysts with lithium and zinc enhancers for the esterification reaction of rapeseed oil and methanol to produce biodiesel as a renewable and alternative fuel for fossil fuels. Is. First, Zn-Li / CaO catalysts with weight ratio Li: Zn: CaO, 2: 2: 7 and by combining different percentages of Li100% promoter, Li75% -Zn25%, Li50% -Zn50%, Li25% -Zn75%, 100% Zn were made on the basis of CaO by wet inoculation. Characterization tests to evaluate the structure and characterization such as X-ray diffraction (XRD) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (EDX) spectroscopy, Bruner-Emmett-Teller...