Search for: electrochemical-properties
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    Lithium Iron Silicate Sol-Gel Synthesis and Electrochemical Investigation

    , M.Sc. Thesis Sharif University of Technology Oghbaei, Morteza (Author) ; Asgari, Sirous (Supervisor)
    Recently lithium iron silicate (Li2FeSiO4) has been used as a new cathode material for lithium ion battery. Li2FeSiO4 has such benefits like low raw material price so lower production cost, lower environmental pollution, higher safety, electro chemical and cyclic stability and high theoretical capacity of 166 mAh/g against other cathode materials like LiMn2O4, LiBNiO2, LiCoO2 and LiFePO4. In this research Li2FeSiO4 was synthesized through sol gel synthesis method and effect of chelating agent concentration, calcination temperature and time has been investigated. To determine the appropriate calcination temperature range, TG/DTA was performed. Then the dried gel powder was calcined at each... 

    Influence of Temperature on Microstructure and Performance of a Lithium-ion Battery

    , M.Sc. Thesis Sharif University of Technology Zaker, Nafiseh (Author) ; Asgari, Sirous (Supervisor)
    In this study, the effect of temperature on the microstructure and electrochemical properties of the NMC batteries has been studied. An extensive set of accelerated aging tests has been carried out employing a Li-ion high energy 18650 system (2.2 Ah, negative electrode: carbon, positive electrode: Li(Ni0.5Mn0.3Co0.2) O2. Different influence factors on cycle aging, such as temperature and discharge rate have been investigated. The aged 18650 cells have been inspected via scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), impedance spectroscopy, and X-ray diffraction (XRD) after disassembly to find more information about the chemical reasons of the degradation and... 

    Synthesis of Sr3Fe2O7and Investigation of the Effect of Pr in Sr Site and Co in Fe Site as a Dopant on the Microstructure and its Function as a Solid Oxide Fuel Cathode

    , M.Sc. Thesis Sharif University of Technology Ghani Harzand, Ayda (Author) ; Nemati, Ali (Supervisor) ; Golmohammad, Mohammad (Supervisor)
    Nowday, one of the important goals of researchers is to develop and improve the properties of intermediate tempreture solid oxide fuel cells with range of 600-800˚C. Therefore, choosing the right material as a cathode with good performance in this temperature range is very important. For this purpose, various materials with ionic and electron conductivity mixtures (MIECs) are used, especially oxides with a Radelsden-Paper structure. These oxides are shown by the formula An+1BnC3n+1, which are actually composed of a combination of perovskite layers (ABO3) that are alternately superimposed between two layers of rock salt (AO). In the present study, Sr3Fe2O7 powder with different amounts... 

    Fabrication and Characterization of Electrochemical Properties of Porous Ni and Ni/rGO Nanocomposite by Electrochemical Deposition for Pseudocapacitor Application

    , M.Sc. Thesis Sharif University of Technology Sabzeh, Parisa (Author) ; Abachi, Parvin (Supervisor) ; Dolati, Abolghasem (Supervisor)
    Fabrication of porous hybrid coatings, specially in combination with carbon compounds, can improve the electrochemical behavior of the coating. In this study, graphene oxide (GO) was first synthesized by tour method. After examining different methods to create a porous coating, the electrochemical coating method for simultaneous deposition of GO and nickel on the copper substrate was selected. CTAB was used to form nanometer porosity in the coating structure. In order to investigate the effect of GO on the properties of the deposited coating, two porous coatings of nickel (Ni) and nickel reduced-graphene oxide (Ni-rGO) were investigated by different analyzes. These analyzes include FESEM... 

    A study on mutual interaction between atomistic and macroscopic phenomena during electrochemical processes using FD-KMC model: Application to CV test in simple copper sulfate bath

    , Article Journal of Electroanalytical Chemistry ; Volume 592, Issue 1 , 2006 , Pages 95-102 ; 15726657 (ISSN) Saedi, A ; Sharif University of Technology
    Elsevier  2006
    A multiscale FD-KMC model has been developed to simulate the cyclic voltammetry test of a copper electrode in simple copper sulfate bath. In this coupled model, the FD code provides the cupric ion concentration on OHP for KMC code, while the KMC code provides the electrochemical properties of the copper electrode (surface activity and rate constants of redox reactions) as an input data for FD code. The changes in the electrode properties due to the atomistic phenomena (deposition dissolution and surface diffusion) have been studied for the present potentiodynamic system. The results showed that the CV process consists of some distinct stages, so that the electrode exhibits a specific... 

    Nickel-doped monoclinic WO3 as high performance anode material for rechargeable lithium ion battery

    , Article Journal of Electroanalytical Chemistry ; Volume 894 , 2021 ; 15726657 (ISSN) Rastgoo Deylami, M ; Javanbakht, M ; Omidvar, H ; Hooshyari, K ; Salarizadeh, P ; Askari, M. B ; Sharif University of Technology
    Elsevier B.V  2021
    The anode materials are one of the critical components in rechargeable lithium ion batteries (LIBs). The monoclinic tungsten trioxide (mWO3) is introduced as interesting anode electrode for LIBs due to its good structure for intercalation and de-intercalation of lithium ions, high abundance and various oxidation state of tungsten and etc. In this study, we prepare and investigate the effect of various amounts of nickel dopant on characteristics and electrochemical properties of the mWO3 as the anode electrode in a rechargeable LIB. The experimental investigations confirm that the number of nickel atoms has a remarkable effect on controlling spherical particle diameter, crystallite size, and... 

    A study of the electrophoretic deposition of bioactive glass-chitosan composite coating

    , Article Ceramics International ; Volume 38, Issue 1 , January , 2012 , Pages 471-476 ; 02728842 (ISSN) Mehdipour, M ; Afshar, A ; Sharif University of Technology
    Bioactive glass is coated on implant's surface to improve corrosion resistance and osseointegration, when placed in the body. Bioactive glass particles were synthesized through a sol-gel process and deposited along with chitosan to form a composite coating on a stainless steel substrate using electrophoretic deposition technique. Stable suspensions of chitosan-bioactive glass were prepared using bioactive glass particles (<1 μm) and 0.5 g/l chitosan solution. The influence of ethanol-water ratio on deposition yield was investigated. For all process conditions, best results were achieved with suspension of 30 vol% water in ethanol-water containing 2 g/l bioactive glass. FTIR studies showed... 

    A comparative investigation of the electrocatalytic oxidation of methanol on poly-NiTCPP and poly-TCPP/Ni modified glassy carbon electrodes

    , Article Journal of Electroanalytical Chemistry ; Volume 663, Issue 1 , December , 2011 , Pages 14-23 ; 15726657 (ISSN) Jafarian, M ; Haghighatbin, M. A ; Gobal, F ; Mahjani, M. G ; Rayati, S ; Sharif University of Technology
    Electro-oxidation of methanol in alkaline solution at a glassy carbon electrode electrochemically modified by a conductive polymeric meso-tetra(4-carboxyphenyl)porphyrinato nickel(II), abbreviated as poly-NiTCPP and also meso-tetra(4-carboxyphenyl)porphyrin with incorporated nickel(II) cations, abbreviated as, poly-TCPP/Ni, were investigated and compared. Both films were prepared by oxidative electro-polymerization of complexes by repetitive cyclic voltammetry (RCV) in 0.1 M NaOH aqueous solution. The electrochemical properties and behaviors and also kinetic values of both films have been characterized and compared using cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical... 

    A new strategy on utilizing nitrogen doped TiO2 in nanostructured solar cells: Embedded multifunctional N-TiO2 scattering particles in mesoporous photoanode

    , Article Materials Research Bulletin ; Volume 72 , 2015 , Pages 64-69 ; 00255408 (ISSN) Shogh, S ; Mohammadpour, R ; Iraji zad, A ; Taghavinia, N ; Sharif University of Technology
    Elsevier Ltd  2015
    Aggregated sub-micron size nitrogen doped TiO2 (N-TiO2) particles with superior optical and electrical features were successfully synthesized for embedding into commercial mesoporous TiO2 photoelectrode of dye sensitized solar cells (DSSCs) as the light scattering particles compared to undoped one. X-ray photoelectron spectroscopy and absorption spectra confirmed that the titanium dioxide is sufficiently doped by nitrogen in N-TiO2 sample. Employing these high-surface N-TiO2 in mesoporous photoelectrode of solar cells, the power conversion efficiency of 8% has been achieved which shows 17% improvement for the optimum embedded level of... 

    Facile synthesis of titanium nitride-graphene nanocomposite and its improved rate-dependent electroactivity with respect to lithium storage

    , Article Materials Research Bulletin ; Volume 84 , 2016 , Pages 388-396 ; 00255408 (ISSN) Yousefi, E ; Ghorbani, M ; Dolati, A ; Yashiro, H ; Sharif University of Technology
    Elsevier Ltd 
    Titanium nitride/graphene nanocomposite as an anode material of lithium ion batteries has been fabricated through the reaction of TiCl4 and NaN3 in supercritical benzene medium followed by ammonia treating at 1000 °C for 10 h. The synthesized TiN/G nanocomposite depicts rate-dependent behavior in such a way that it shows specific capacity of 115 mAh g−1 when is cycled at higher rate (1.6 C) while it shows 76 mAh g−1 when is cycled initially at lower rate (0.2 C) and is subsequently subjected to higher rate (1.6 C). Moreover, TiN/G anode demonstrates capacity retention of 112%, 100%, and 70% after 250 cycles at charge/discharge rates of 1.6, 0.7, and 0.2 C, respectively. This unusual behavior... 

    Band-gap narrowing and electrochemical properties in N-doped and reduced anodic TiO2 nanotube arrays

    , Article Electrochimica Acta ; Volume 270 , 2018 , Pages 245-255 ; 00134686 (ISSN) Peighambardoust, N. S ; Khameneh Asl, S ; Mohammadpour, R ; Khameneh Asl, S ; Sharif University of Technology
    Elsevier Ltd  2018
    Electrochemical activity of TiO2 nanotube arrays (NTAs) is restricted by a wide band gap of TiO2. To overcome this restriction, we considered systematic research on two effective methods of doping of TiO2 NTAs such as the N-doping and electrochemical reductive doping and predicting the proper application of them. Band gap narrowing was occurred from 3.16 eV for undoped TiO2 NTAs to 2.9 and 2.7 eV at N-doped and self-doped TiO2 ones respectively. The electrochemical responses of the TiO2 NTAs before and after doping were examined by cyclic Voltammetry (CV) curve. To understand the electrochemical behavior of the undoped and doped TiO2 NTAs, electrochemical impedance spectroscopy (EIS) was... 

    PVDF/PU blend membrane separator for lithium-ion batteries via non-solvent-induced phase separation (NIPS)

    , Article Journal of Solid State Electrochemistry ; Volume 25, Issue 8-9 , 2021 , Pages 2385-2394 ; 14328488 (ISSN) Javadi, O ; Fathollahi Zonouz, A ; Soltanieh, M ; Mousavi, S. A ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    Membrane separator based on the polyvinylidene fluoride (PVDF) is prepared via the non-solvent-induced phase separation (NIPS) method with water and ethanol as non-solvent and a mixture of dimethylformamide (DMF) and acetone as solvent. The effect of various acetone/DMF ratios and non-solvent material on the physical and electrochemical properties of the separator is studied by FE-SEM, tensile strength, electrochemical AC-impedance spectroscopy (EIS), thermal stability, and linear sweep voltammetry (LSV). The charge-discharge studies are carried out by fabricating a lithium foil/polymer electrolyte membrane/LiFePO4 cell. The results show that with the change of solvent and non-solvent, the... 

    AC impedance and cyclic voltammetry studies on PbS semiconducting film prepared by electrodeposition

    , Article Journal of Electroanalytical Chemistry ; Volume 661, Issue 1 , 2011 , Pages 265-269 ; 15726657 (ISSN) Aghassi, A ; Jafarian, M ; Danaee, I ; Gobal, F ; Mahjani, M. G ; Sharif University of Technology
    Semiconducting lead sulfide film was deposited on Stainless Steel (SS) electrode by cyclic voltammetry (CV) at room temperature. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry were used to investigate the electrochemical properties of PbS film in Na2SO4 solution. The voltammetric results showed that oxidative dissolution of PbS film occurred at about 0.21 V vs. Ag/AgCl and total film detachment from the surface occurs with increasing potential. It is concluded that the electrode surface was not passivated by sulfur produced from oxidative dissolution of PbS film. Also, cathodic reduction of the film continued to beyond the hydrogen evolution at -1.35 V vs. Ag/AgCl.... 

    Synthesis and electrochemical properties of LiNi0.8Co 0.2O2 nanopowders for lithium ion battery applications

    , Article Journal of Power Sources ; Volume 196, Issue 1 , 2011 , Pages 337-342 ; 03787753 (ISSN) Jouybari, Y.H ; Asgari, S ; Sharif University of Technology
    Nitrates of lithium, cobalt and nickel are utilized to synthesize LiNi 0.8Co0.2O2 cathode material through sol-gel technique. Various synthesis parameters such as calcination time and temperature as well as chelating agent are studied to determine the optimized condition for material processing. Using TG/DTA techniques, the optimized calcination temperatures are selected. Different characterization techniques such as ICP, XRD and TEM are employed to characterize the chemical composition, crystal structure, size and morphology of the powders. Micron and nano-sized powders are produced using citric/oxalic and TEA as chelating agent, respectively. Selected powders are used as cathode material... 

    Influence of vanadium, cobalt-codoping on electrochemical performance of titanium dioxide bronze nanobelts used as lithium ion battery anodes

    , Article Journal of Materials Science: Materials in Electronics ; 2018 , Pages 1-9 ; 09574522 (ISSN) Amirsalehi, M ; Askari, M ; Sharif University of Technology
    Springer New York LLC  2018
    In this work, V, Co-codoped TiO2(B) samples are synthesized through a hydrothermal method, and used as negative electrode materials for lithium ion batteries. The amount of dopants is varied in order to investigate their influence on electrochemical properties. The formation of V, Co-codoped TiO2(B) nanobelts with widths of 20 and 60 nm is demonstrated using X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma–optical emission spectrometry and field-emission scanning electron microscopy analyses. In addition, the electrochemical properties of the samples are tested by cyclic voltammetry, charging/discharging, and cyclic performance techniques. Compared to other... 

    Highly sensitive voltammetric determination of lamotrigine at highly oriented pyrolytic graphite electrode

    , Article Bioelectrochemistry ; Volume 84 , 2012 , Pages 38-43 ; 15675394 (ISSN) Saberi, R. S ; Shahrokhian, S ; Sharif University of Technology
    The electrochemical behavior of lamotrigine (LMT) at the pyrolytic graphite electrode (PGE) is investigated in detail by the means of cyclic voltammetry. During the electrochemical reduction of LMT, an irreversible cathodic peak appeared. Cyclic voltammetric studies indicated that the reduction process has an irreversible and adsorption-like behavior. The observed reduction peak is attributed to a two-electron process referring to the reduction of azo group. The electrode showed an excellent electrochemical activity toward the electro-reduction of LMT, leading to a significant improvement in sensitivity as compared to the glassy carbon electrode. The results of electrochemical impedance... 

    Electrochemical determination of l-dopa in the presence of ascorbic acid on the surface of the glassy carbon electrode modified by a bilayer of multi-walled carbon nanotube and poly-pyrrole doped with tiron

    , Article Journal of Electroanalytical Chemistry ; Volume 636, Issue 1-2 , 2009 , Pages 40-46 ; 15726657 (ISSN) Shahrokhian, S ; Asadian, E ; Sharif University of Technology
    Elsevier  2009
    There are high attractions in the development of conducting polymer (CP) coatings to improve the electrochemical properties and biocompatibility of electrodes in the area of biosensors. A new type of the modified electrodes is prepared in a layer-by-layer process by using multi-walled carbon nanotube (MWCNT) and poly-pyrrole. In this procedure, the glassy carbon electrode is casted by a drop suspension of MWCNT, which leads to form a thin film of nanotube on its surface. In the second step, electrochemical polymerization of pyrrole in the presence of tiron (used as doping anion) is performed on the surface of the MWCNT pre-coated electrode. The modification procedure led to fabrication of a...