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1.
CeO2–TiO2–ZrO2 thin films were prepared using the sol–gel process and deposited on glass and ITO-coated glass substrates via dip-coating technique. The samples were heat treated between 100 and 500 °C. The heat treatment effects on the electrochromic performances of the films were determined by means of cyclic voltammetry measurements. The structural behavior of the film was characterized by atomic force microscopy and X-ray diffraction. Refractive index, extinction coefficient, and thickness of the films were determined in the 350–1000 nm wavelength, using nkd spectrophotometry analysis.Heat treatment temperature affects the electrochromic, optical, and structural properties of the film. The charge density of the samples increased from 8.8 to 14.8 mC/cm2, with increasing heat-treatment temperatures from 100 to 500 °C. It was determined that the highest ratio between anodic and cathodic charge takes place with increase of temperature up to 500 °C. 相似文献
2.
S.Y. Chew T.J. Patey O. Waser S.H. Ng R. Büchel A. Tricoli F. Krumeich J. Wang H.K. Liu S.E. Pratsinis P. Novák 《Journal of power sources》2009
A new approach has been developed to rapidly synthesize nanostructured LiMn2O4 thin films by flame spray deposition (FSD) and in situ annealing. A precursor solution of lithium acetylacetonate and manganese acetylacetonate in an organic solution was supplied through a flame spray pyrolysis (FSP) reactor. The liquid solution spray was ignited and stabilized by a premixed methane/oxygen flame ring surrounding the FSP nozzle. Thus, LiMn2O4 nanoparticles were formed by combustion and deposited onto a current collector followed by in situ annealing. Two different types of current collectors, i.e. stainless steel and aluminum coated with carbon-based primer were tested. The prepared thin films were characterized by X-ray diffraction and field-emission scanning electron microscopy. The electrochemical properties of the thin films were evaluated by cyclic voltammetry and galvanostatic cycling. The LiMn2O4 films exhibited good cyclability. Films that underwent sintering and crystal growth during in situ annealing developed more robust film structures on the current collector surface and exhibited better electrochemical performance than poorly adhered films. 相似文献
3.
A. Rougier A. Blyr J. Garcia Q. Zhang S. A. Impey 《Solar Energy Materials & Solar Cells》2002,71(3):1188
Mixed vanadium and niobium tungsten oxide W–M–O (M=V, Nb) thin films were prepared by sol-gel from solution of tungsten oxychloride (WOCl4) and vanadium oxypropoxide (VO(OPri)3) or niobium oxybutoxide (Nb(OBun)5), respectively. The annealing temperature and time were optimized to 200°C and 10 min. W–M–O (M=V, Nb) thin films were characterized by means of optical (transmittance) and electrochemical (cyclic voltammetry) methods. Evidence of different electrochemical behaviour is given where the presence of either vanadium or niobium leads to more neutral coloured films. 相似文献
4.
Vanadium and tantalum-doped vanadium pentoxide, V2O5 and V2O5:Ta thin films (2.5 and 5 mol% of Ta) were prepared using sol–gel dip-coating technique.The coating solutions were prepared by reacting vanadium (V) oxytripropoxide and tantalum ethoxide (V) as precursors using anhydrous isopropyl alcohol as solvent.The films were deposited on a transparent glass substrate with ITO conducting film by dip-coating technique, with a withdrawal of 20 cm/min from the vanadium–tantalum solution and heat treated at 300 °C for 1 h. The resulting films were characterized by cyclic voltammetry, optical spectroscopy and by X-ray diffraction analysis (XRD). XRD data show that the films thermally treated at 300 °C were crystalline.A charge density of 70 mC/cm2 was obtained for the film with 5 mol% of Ta, with an excellent stability up to 1500 cycles. 相似文献
5.
LiNi0.5Mn0.5O2 thin films have been deposited on the NASICON-type glass ceramics, Li1+x+yAlxTi2−xSiyP3−yO12 (LATSP), by radio frequency (RF) magnetron sputtering followed by annealing. The films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy. All-solid-state Li/PEO18-Li(CF3SO2)2N/LATSP/LiNi0.5Mn0.5O2/Au cells are fabricated using the LiNi0.5Mn0.5O2 thin films and the LATSP electrolyte. The electrochemical performance of the cells is investigated by galvanostatic cycling, cyclic voltammetry (CV), potentiostatic intermittent titration technique (PITT) and electrochemical impedance spectroscopy (EIS). Interfacial reactions between LiNi0.5Mn0.5O2 and LATSP occur at a temperature as low as 300 °C with the formation of Mn3O4, resulting in an increased obstacle for Li-ion diffusion across the LiNi0.5Mn0.5O2/LATSP interface. The electrochemical performance of the cells is limited by the interfacial resistance between LATSP and LiNi0.5Mn0.5O2 as well as the Li-ion diffusion kinetics in LiNi0.5Mn0.5O2 bulk. 相似文献
6.
Zohreh Merati Jalal Basiri Parsa Rasoul Babaei-Sati 《International Journal of Hydrogen Energy》2018,43(45):20993-21005
As known, a good support enhances the activity and durability of any catalyst. In the current study, polypyrrole (PPY)/nanocomposite (MWCNTs and Al2O3) films were fabricated by electrochemical polymerization of pyrrole solution with a certain amount of nanoparticles on titanium substrates and were used as new support materials for Pt catalyst. The modified electrodes were characterized by Fourier transform infrared (FT-IR) spectroscopy, field-emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray analysis (EDX) techniques. High catalytic activity and long-time stability toward methanol oxidation of Pt/PPY–MWNTs-αAl2O3 catalyst have also been verified by cyclic voltammetry results and chronoamperometric response measurements. This catalyst exhibits a vehemently high current density (345.03 mA cm?2) and low peak potential (0.74 v) for methanol oxidation. Other electrochemical measurements (electrochemical impedance spectroscopy (EIS), CO stripping voltammetry and Tafel test) clearly confirmed that Pt/PPY–MWNTs-αAl2O3/Ti electrode has a better performance toward methanol oxidation compared to the other electrodes and that can be used as a promising electrode material for application in direct methanol fuel cells (DMFCs). 相似文献
7.
Csar O. Avellaneda Marcos A.C. Berton Luis O.S. Bulhes 《Solar Energy Materials & Solar Cells》2008,92(2):240-244
Transparent CeO2 thin solid films, used as ion storage layer in electrochromic devices were prepared by the sol–gel method using an alkoxide route combined with the dip-coating technique. The precursor sol was prepared from a mixture of cerium (IV) methoxyethoxide in anhydrous 2-butanol. Electrochemical Li+ intercalation/deintercalation was performed by cyclic voltammetry and the results indicate that the CeO2/LiClO4 system is electrochemically reversible. The total inserted/extracted charge of the CeO2 film was determined by chronoamperometric measurements, which showed an ion storage capacity of 14 mC/cm2. The solid-state diffusion of lithium ion into the CeO2 thin films was investigated by electrochemical impedance spectroscopy. 相似文献
8.
Inverse spinel LiNiVO4 thin films were prepared by rf-sputtering, fallowed by films annealed at 300, 450 and 600 °C for 2 h to induce the crystallization of the films. The films were characterized by X-ray diffraction, Rutherford backscattering spectroscopy, nuclear reaction analysis, Auger electron spectroscopy, atomic force microscopy and scanning electron microscope techniques. The Anodic electrochemical performance films have been cycled in the range of 0.02–3.0 V, at room temperature, at a current density 75 μA cm−2. Galvanostatic cycling and cyclic voltammetry results shows characteristic cycling curves with respect to annealing temperature. The films annealed at 450 °C showed best electrochemical performance and excellent capacity retention during cycling was observed due to its nanosized morphology. 相似文献
9.
LiCoO2 thin films were deposited on the NASICON-type glass ceramics, Li1+x+yAlxTi2−xSiyP3−yO12, by radio frequency (RF) magnetron sputtering and were annealed at different temperatures. The as-deposited and the annealed LiCoO2 thin films were characterized by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). It was found that the films exhibited a (1 0 4) preferred orientation after annealing and Co3O4 was observed by annealing over 500 °C due to the reaction between the LiCoO2 and the glass ceramics. The effect of annealing temperature on the interfacial resistance of glass ceramics/LiCoO2 and Li-ion transport in the bulk LiCoO2 thin film was investigated by galvanostatic cycling, cyclic voltammetry (CV), potentiostatic intermittent titration technique (PITT) and electrochemical impedance spectroscopy (EIS) with the Li/PEO/glass ceramics/LiCoO2 cell. The cell performance was limited by the Li-ion diffusion resistance in Ohara/LiCoO2 interface as well as in bulk LiCoO2. 相似文献
10.
This work introduces a new method to synthesize Li3Fe2(PO4)3 nanoparticles in the nanopowder form and study its electrochemical performance by cyclic voltammetry and battery tests. Li3Fe2(PO4)3 is synthesized by the gel combustion method based on polyvinyl alcohol (PVA) as gel making agent. The optimum conditions of the synthesis include 8 wt% PVA, 0.34 wt% lithium slat, 1 wt% iron salt, 0.57 wt% ammonium dihydrogen phosphate, ethanol-water 50:50 as solvent, 675 °C combustion temperature and 4 h combustion time. Characterization of the samples is performed by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), EDX analysis, XRD patterns, BET specific surface area and DSL size distribution. In the optimum conditions, a nanopowder is obtained that consisting of uniform nanoparticles with an average diameter of 70 nm. The optimized sample shows 12.5 m2 g−1 specific surface areas. Cyclic voltammetry (CV) studies show that the synthesized compound has good reversibility and high cyclic stability. The CV results are confirmed by the battery tests. The obtained results show that the synthesized cathodic material has high practical discharge capacity (average 125.5 mAh g−1 approximately same with its theoretical capacity 128.2 mA h−1) and long cycle life. 相似文献
11.
Igor V. Elmanovich Mikhail S. Kondratenko Dmitry O. Kolomytkin Marat O. Gallyamov Alexei R. Khokhlov 《International Journal of Hydrogen Energy》2013
In the present work we suggest a new approach to the thin-film design of active layers for electrodes of fuel cells with phosphoric acid electrolyte in a polymer matrix. A fluoropolymer binder is introduced into common Pt@C active layer materials using supercritical (SC) CO2 as a solvent. Unique wetting properties of this non-hazardous and environmentally friendly solvent allow one to deposit highly uniform thin fluoropolymer films on dispersed carbon supports. As a result, well-percolated gas-permeable fluoropolymer phases are produced in active layers already at comparatively small polymer loadings. Teflon AF 2400 was chosen as a stable high-molecular-weight fluoropolymer soluble in SC CO2 with high oxygen permeability and high Tg value. Fluoropolymer-containing active layer materials prepared via the SC CO2 deposition routes were studied by means of cyclic voltammetry and were tested in operating fuel cells using steady state voltammetry and electrochemical impedance spectroscopy. Polarization curves of operating fuel cells indicate that the optimal content of deposited from SC CO2 fluoropolymer in active layer is about 3–5%. Results of impedance spectra fitting yield information used to explain the detected values of optimal loading. 相似文献
12.
The electrolytic deposition of Co3O4 thin films on stainless steel was conducted in Co(NO3)2 aqueous solution for anodes in lithium-ion thin film batteries. Three major electrochemical reactions during the deposition were discussed. The coated specimens and the coating films carried out at −1.0 V (saturated KCl Ag/AgCl) were subjected to annealing treatments and further characterized by XRD, TGA/DTA, FE-SEM, Raman spectroscopy, cyclic voltammetry (CV) and discharge/charge cyclic tests. The as-coated film was β-Co(OH)2, condensed into CoO and subsequently oxidized into nano-sized Co3O4 particles. The nano-sized Co3O4, CoO, Li2O and Co particles revealed their own characteristics different from micro-sized ones, such as more interfacial effects on chemical bonding and crystallinity. The initial maximum capacity of Co3O4 coated specimen was 1930 mAh g−1 which much more than its theoretical value 890 mAh g−1, since the nano-sized particles offered more interfacial bondings for extra sites of Li+ insertion. However, a large ratio of them was trapped, resulting in a great part of irreversible capacity during the first charging. Still, it revealed a capacity 500 mAh g−1 after 50 discharged-charged cycles. 相似文献
13.
E. Ozkan Zayim I. Turhan F.Z. Tepehan N. Ozer 《Solar Energy Materials & Solar Cells》2008,92(2):164-169
The electrochromic (EC) behavior, the microstructure, and the morphology of sol–gel deposited nickel oxide (NiOx) coatings were investigated. The films were produced by spin and dip-coating techniques on indium tin oxide (ITO)/glass and Corning glass (2947) substrates.The coating solutions were prepared by reacting nickel(II) 2-ethylhexanoate as the precursor, and isopropanol as the solvent. NiOx was heat treated at 350 °C for 1 h. The surface morphology, crystal structure, and EC characteristics of the coatings were investigated by scanning electron microscopy (SEM), electron dispersive spectroscopy (EDS), atomic force spectroscopy (AFM), X-ray diffractometry (XRD), and cyclic voltammetry (CV).SEM and AFM images revealed that the surface morphology and surface characteristics of the spin- and dip-coated films on both types of substrate were different. XRD spectra revealed that both films were amorphous, either on ITO or Corning glass substrates. CV showed a reversible electrochemical insertion or extraction of the K+ ions, cycled in 1 M KOH electrolyte, in both type of film. The crystal structure of the cycled films was found to be XRD amorphous. Spectroelectrochemistry demonstrated that dip-coated films were more stable up to 1000 coloration–bleaching cycles, whereas spin-coated films gradually degraded after 500 cycles. 相似文献
14.
The switchable optical properties of Pd-protected RCo2-type Ho0.6Mm0.4Co2 alloy thin films have been investigated in a KOH electrolyte. The reversible optical switching has been carried out simultaneously by measuring transmitted light through the thin film during electrochemical charging–discharging of hydrogen. The dependence of switching speed and cyclic durability of the film on the charging and discharging current density as well as concentration of KOH electrolyte has been studied. In addition, cyclic voltammetric measurements have been performed to examine the hydride formation and decomposition reactions. 相似文献
15.
Rahul Singhal Suprem R. Das Maharaj S. Tomar Osbert Ovideo Santander Nieto Ricardo E. Melgarejo Ram S. Katiyar 《Journal of power sources》2007
Spinel powders of LiMn1.99Nd0.01O4 have been synthesized by chemical synthesis route to prepare cathodes for Li-ion coin cells. The structural and electrochemical properties of these cathodes were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, cyclic voltammetry, and charge-discharge studies. The cyclic voltammetry of the cathodes revealed the reversible nature of Li-ion intercalation and deintercalation in the electrochemical cell. The charge-discharge characteristics for LiMn1.99Nd0.01O4 cathode materials were obtained in 3.4–4.3 V voltage range and the initial discharge capacity of this material were found to be about 149 mAh g−1. The coin cells were tested for up to 25 charge-discharge cycles. The results show that by doping with small concentration of rare-earth element Nd, the capacity fading is considerably reduced as compared to the pure LiMn2O4 cathodes, making it suitable for Li-ion battery applications. 相似文献
16.
Starting from the aqueous solution of titanium(IV) oxalate complexes and controlling electrochemical conditions using a cyclic voltammetry (CV) method, the thin layers of TiO2 on platinum were obtained, which after additional heat treatment, at 450 °C, were still of amorphous nature. The amorphous state of the samples, containing an admixture of crystalline anatase, was confirmed by Raman spectroscopy and by a variety of electrochemical techniques. The new electrochemical procedure allows preparing the oxide with different morphologies. By the comparison with the peroxotitanium route, the oxalate precursor method offers the possibility of the synthesis of amorphous TiO2 at higher temperatures that is the essential key for the cycling stability of the oxide if one is used as an anode material in lithium ion batteries. The results from cycling voltammetry revealed that electrodeposited TiO2 reversibly and fast intercalates lithium ions due to its high internal surface area. Therefore, the nanostructural morphology facilitates lithium ion intercalation which was monitored and confirmed in all electrochemical testing. The specific capacity of the TiO2 approaches the value of 145 mAh g−1 at 8 C-rate in the best case. From the electrochemical impedance spectroscopy (EIS) measurements in connection with SEM investigations, it was concluded that Li+ diffusion is the finite space process and its rate is depending on the size of the crystallites building the oxide films. Evaluated values of the D-coefficients are of the order of 10−14 cm2 s−1. 相似文献
17.
In addition to lattice doping and carbon-coating, surface modification with other metal oxides can also improve the electrochemical performance of LiFePO4 powders. In this work, highly conductive vanadium oxide (V2O3) is in situ produced during the synthesis of carbon-coated LiFePO4 (LiFePO4/C) powders by a solid state reaction process and acts as a surface modifier. The structures and compositions of LiFePO4/C samples containing 0-10 mol% vanadium are analyzed by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. Their electrochemical properties are also characterized with galvanostatic cell cycling and cyclic voltammetry. It is found that vanadium is present in the form of V2O3 that is incorporated in the carbon phase. The vanadium-modified LiFePO4/C samples show improved rate capability and low-temperature performance. Their apparent lithium diffusion coefficient is in the range of 10−12 to 10−10 cm2 s−1 depending on the vanadium content. Among the investigated samples, the one with 5 mol% vanadium exhibits the best electrochemical performance. 相似文献
18.
P.S. Patil P.S. Chigare S.B. Sadale S.H. Mujawar P.S. Shinde 《Solar Energy Materials & Solar Cells》2007,91(10):859-863
Tin oxide (SnO2) thin films were prepared by a simple and inexpensive spray pyrolysis technique from an aqueous solution at various substrate temperatures viz. 300, 400 and 500 °C, and their electrochemical studies have been carried out. The thin films have been optically and electrochemically characterized by means of transmittance, cyclic voltammetry and chronoamperometry. The mechanism of reduction and oxidation reactions that took place during the potential cycling is presented. The samples deposited at 500 °C exhibit better performance in terms of coloration efficiency, reversibility, contrast ratio and response time. 相似文献
19.
B. El Idrissi M. Addou A. Outzourhit M. Regragui A. Bougrine A. Kachouane 《Solar Energy Materials & Solar Cells》2001,69(1)
Cerium dioxide (CeO2) thin films were prepared by spray pyrolysis using hydrated cerium chloride (CeCl3·7H2O) as source compound. The films prepared at substrate temperatures below 300°C were amorphous, while those prepared at optimal conditions (Ts=500°C,s=5 ml/min) were polycrystalline, cubic in structure, preferentially oriented along the (2 0 0) direction and exhibited a transmittance value greater than 80% in the visible range. The cyclic voltammetry study showed that films of CeO2 deposited on ITO pre-coated glass substrates were capable of charge insertion/extraction when immersed in an electrolyte of propylene carbonate with 1 M LiClO4.These films also remained fully transparent after Li+ intercalation/deintercalation. 相似文献
20.
Zn3P2 semiconductor thin films were prepared by electrodeposition technique form aqueous solutions. The deposition mechanism was investigated by cyclic voltammetry technique. Crystal structure, morphology and composition of as deposited and annealed Zn3P2 thin films grown on SnO2/glass substrates were determined by X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray analysis. X-ray diffraction data indicated the formation of Zn3P2 as the predominant phase for both as-deposited and annealed films. The compositions of the deposited films were controlled by the bath temperature, deposition potential and Zn/P ratio in the solution.The dark current–voltage measurements of SnO2/Zn3P2/C devices indicated a rectifying behavior and a reverse saturation current density of 1.7×10−7 A/cm2, which is in good accordance with that obtained from films prepared using vacuum technique. Also, the capacitance–voltage measurements showed that the number of interface states and the built in potential are in the order of 5×10−9 cm−3 and 0.85 V, respectively. These preliminary results for Zn3P2 thin films reveal that, this semiconductor material can be used for solar cell applications. 相似文献