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1.
Aerosol flame pyrolysis deposition method was applied to deposit the oxide glass electrolyte film and LiCoO2 cathode for thin film type Li-ion secondary battery. The thicknesses of as-deposited porous LiCoO2 and Li2O–B2O3–P2O5 electrolyte film were about 6 μm and 15 μm, respectively. The deposited LiCoO2 was sintered for 2 min at 700 °C to make partially densified cathode layer, and the deposited Li2O–P2O5–B2O3 glass film completely densified by the sintering at 700 °C for 1 h. After solid state sintering process the thicknesses were reduced to approximately 4 μm and 6 μm, respectively. The cathode and electrolyte layers were deposited by continuous deposition process and integrated into a layer by co-sintering. It was demonstrated that Aerosol flame deposition is one of the good candidates for the fabrication of thin film battery.  相似文献   

2.
This study examined the electrochemical deposition and dissolution of lithium on nickel electrodes in a propylene carbonate (PC) electrolyte containing different LiN(SO2C2F5)2 concentrations. The electrolyte concentration was found to have a significant effect on the reactions occurring at the electrode. The poor cycleability of the electrodes in the low-concentration solutions was improved considerably by increasing the electrolyte concentration. Transmission electron microscopy (TEM) revealed that a high-concentration solution produces a thinner solid electrolyte interphase (SEI) on the electrodeposited lithium than a low-concentration solution, e.g., ∼35 nm in 1.28 mol kg−1 vs. ∼20 nm in 3.27 mol kg−1 solutions. Raman spectroscopy showed that the solvation number of lithium ions differed according to the electrolyte concentration. This suggests that the structure of solvated lithium ions is an important factor in suppressing dendritic lithium formation.  相似文献   

3.
We measured 785 nm excited Raman and infrared spectra of pentacene-d14. The observed spectra were assigned on the basis of the Raman and infrared spectra calculated by the density functional theory (DFT) method at the B3LYP/6⬜311 + G** level. We measured 785 nm excited Raman spectrum of a pentacne-d14:C60 bulk heterojunction film. The spectrum was assigned on the basis of the wavenumber shifts upon deuteration of pentacene. The assignments of the 1462 and 493 cm↙1 Ag bands of C60 were confirmed. The 511, 453, and 256 cm↙1 bands, which were observed only in pentacene:C60 bulk heterojunction films, did not show large deuteration shifts. This result indicates that the 511, 453, and 256 cm↙1 bands are attributed to activation of the silent modes of C60 due to symmetry lowering.  相似文献   

4.
The whole range of solid solutions Li(Li(1−x)/3CoxMn(2−2x)/3)O2 (0  x  1) was firstly synthesized by an aqueous solution method using poly-vinyl alcohol as a synthetic agent to investigate their structure and electrochemical properties. X-ray diffraction results indicated that the synthesized solid solutions showed a single phase without any detectable impurity phase and have a hexagonal structure with some additional peaks caused by monoclinic distortion, especially in the solid solutions with a low Co amount. In the electrochemical examination, the solid solutions in the range between 0.2  x  0.9 showed higher discharge capacity and better cyclability than LiCoO2 (x = 1) on cycling between 2.0 and 4.6 V with 100 mA g−1 at 25 °C. For example, Li(Li0.2Co0.4Mn0.4)O2 (x = 0.4) exhibited a high discharge capacity of 180 mA h g−1 at the 50th cycle. By synthesizing the solid solution between Li2MnO3 and LiCoO2, the electrochemical properties of the end members were improved.  相似文献   

5.
High lithiation capacity at low red-ox potentials in combination with good safety characteristics makes amorphous Si as a very promising anode material for rechargeable Li batteries.Thin film silicon electrodes were prepared by DC magnetron sputtering of silicon on stainless steel substrates. Their behavior as Li insertion/extraction electrodes was studied by voltammetry and chronopotentiometry at room temperature in the ionic liquid (IL) 1-methyl-1-propylpiperidinium bis(trifluoromethylsuphonil)imide containing 1 M Li bis(trifluoromethylsuphonil)imide. Li/Si cells containing this electrolyte showed good performance with a stable Si electrodes capacity of about 3000 mA h g−1 and a relatively low irreversible capacity. Preliminary results on cycling Si–LiCoO2 cells using this IL electrolyte are also presented.  相似文献   

6.
Electrochemical lithium intercalation within graphite from 1 mol dm 3 solution of LiClO4 in propylene carbonate (PC) was investigated at 25 and − 15 °C. Lithium ions were intercalated into and de-intercalated from graphite reversibly at − 15 °C despite the use of pure PC as the solvent. However, ceaseless solvent decomposition and intense exfoliation of graphene layers occurred at 25 °C. The results of the Raman spectroscopic analysis indicated that the interaction between PC molecules and lithium ions became weaker at − 15 °C by chemical exchange effects, which suggested that the thermodynamic stability of the solvated lithium ions was an important factor that determined the formation of a solid electrolyte interface (SEI) in PC-based solutions. Charge–discharge analysis revealed that the nature of the SEI formed at − 15 °C in 1 mol dm 3 of LiClO4 in PC was significantly different from that formed at 25 °C in 1 mol dm 3 of LiClO4 in PC containing vinylene carbonate, 3.27 mol kg 1 of LiClO4 in PC, and 1 mol dm 3 of LiClO4 in ethylene carbonate.  相似文献   

7.
Molecular speciation of organic compounds in solution is essential for the understanding of ionic complexation. The Raman technique was chosen because it allows the identification of compounds in different states, and it can give information about the molecular geometry from the analysis of the vibrational spectra. The effect of pH on organic compounds can give information about the ionisation of molecule species. In this study the ionisation steps of salicylic acid and paracetamol have been studied by means of potentiometry coupled with Raman spectroscopy at 30.0 °C in a solution of ionic strength 0.96 mol dm?3 (KNO3) and 0.04 mol dm?3 (HNO3). The protonation and deprotonation behaviour of the molecules were studied in different pH regions. The abundance of the three different species in the Raman spectra of aqueous salicylic acid have been identified satisfactorily, characterised, and determined by numeric treatment of the data using a multiwavelength curve-fitting program and confirmed with the observed spectral information.  相似文献   

8.
We observed the Raman spectra of carriers, positive polarons and bipolarons, generated in a poly(2,5-bis(3-tetradecylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT-C14) film by FeCl3 vapor doping. Electrical conductivity and Raman measurements indicate that the dominant carriers in the conducting state were bipolarons. We identified positive polarons and bipolarons generated in an ionic-liquid-gated transistor (ILGT) fabricated with PBTTT-C14 as an active semiconductor and an ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide [BMIM][TFSI] as a gate dielectric using Raman spectroscopy. The relationship between the source−drain current (ID) at a constant source−drain voltage (VD) and the gate voltage (VG) was measured. ID increased above −VG = 1.1 V and showed a maximum at −VG = 2.0 V. Positive polarons were formed at the initial stage of electrochemical doping (−VG = 0.8 V). As ID increased, positive bipolarons were formed. Above VG = −2.0 V, bipolarons were dominant. The charge density (n), the doping level (x), and the mobility of the bipolarons were calculated from the electrochemical measurements. The highest mobility (μ) of bipolarons was 0.72 cm2 V−1 s−1 at x = 110 mol%/repeating unit (−VG = 2.0 V), whereas the highest μ of polarons was 4.6 × 10−4 cm2 V−1 s−1 at x = 10 mol%.  相似文献   

9.
《Vibrational Spectroscopy》2011,55(2):148-154
The adsorption of 4-aminopyridine (4-AP) on Co and Ag electrodes in acid or alkaline solutions of KCl and KI electrolyte salts were monitored by the Surface-enhanced Raman Spectroscopy (SERS) technique. The SERS intensity for the Ag electrode was in 2 orders of magnitude higher than for the Co electrode, due to the enhancement of the Raman cross-section on Ag by the surface-plasmon excitation. In acidic chloride medium (pH 4), the SERS results for Ag electrodes indicate that the protonated form of 4-AP (4-APH+) adsorbs in the potential range of −0.1 to −0.6 V (Ag|AgCl|KCl sat) through hydrogen-bonding between 4-APH+ and Cl adsorbed on the electrode surface; at more negative potentials the neutral form 4-AP is the predominant adsorbed species. For Co electrode in the same medium, only bands due to neutral 4-AP were observed in the spectra at −0.8 and −0.9 V. For more negative potentials bands assigned to both 4-AP and 4-AP surface complex are observed, with the lasts being enhanced, as the potentials are turned more negative. In alkaline chloride medium (pH 13), for less negative potentials the bands assigned to free 4-AP were observed in the spectra of both Ag and Co surfaces. For more negative potentials, only bands assigned to the 4-AP surface complex were observed. For 0.1 mol L−1 KI acidic or alkaline solutions, bands assigned to 4-AP and 4-APH+ were observed in a wider potential range than in chloride solutions. An adsorption scheme of 4-AP on Ag and Co is proposed for acidic and alkaline solutions.  相似文献   

10.
Early stages of the solid electrolyte interphase (SEI) formation at a tin foil electrode in an ethylene carbonate (EC) based electrolyte were investigated by in situ AFM and cyclic voltammetry (CV) at potentials >0.7 V, i.e., above the potential of Sn–Li alloying. We detected and observed initial steps of the surface film formation at ~2.8 V vs. Li/Li+ followed by gradual film morphology changes at potentials 0.7 < U < 2.5 V. The SEI layer undergoes continuous reformation during the following CV cycles between 0.7 and 2.5 V. The surface film on Sn does not effectively prevent the electrolyte reduction and a large fraction of the reaction products dissolve in the electrolyte. The unstable SEI layer on Sn in EC-based electrolytes may compromise the use of tin-based anodes in Li-ion battery systems unless the interfacial chemistry of the electrode and/or electrolyte is modified.  相似文献   

11.
The paper presents the study of selected montmorillonite standards by Raman spectroscopy and microscopy supported by elemental analysis, X-ray powder diffraction analysis and thermal analysis. Dispersive Raman spectroscopy with excitation lasers of 532 nm and 780 nm, dispersive Raman microscopy with excitation laser of 532 nm and 100× magnifying lens, and Fourier Transform-Raman spectroscopy with excitation laser of 1064 nm were used for the analysis of four montmorillonites (Kunipia-F, SWy-2, STx-1b and SAz-2). These mineral standards differed mainly in the type of interlayer cation and substitution of octahedral aluminium by magnesium or iron. A comparison of measured Raman spectra of montmorillonite with regard to their level of fluorescence and the presence of characteristic spectral bands was carried out. Almost all measured spectra of montmorillonites were significantly affected by fluorescence and only one sample was influenced by fluorescence slightly or not at all. In the spectra of tested montmorillonites, several characteristic Raman bands were found. The most intensive band at 96 cm−1 belongs to deformation vibrations of interlayer cations. The band at 200 cm−1 corresponds to deformation vibrations of the AlO6 octahedron and at 710 cm−1 can be assigned to deformation vibrations of the SiO4 tetrahedron. The band at 3620 cm−1 corresponds to the stretching vibration of structural OH groups in montmorillonites.  相似文献   

12.
Polarized Raman spectroscopy was used to study the lattice structure of BiFeO3 films on different substrates prepared by pulsed laser deposition. Interestingly, the Raman spectra of BiFeO3 films exhibit distinct polarization dependences. The symmetries of the fundamental Raman modes in 50–700 cm−1 were identified based on group theory. The symmetries of the high order Raman modes in 900–1500 cm−1 of BiFeO3 are determined for the first time, which can provide strong clarifications to the symmetry of the fundamental peaks in 400–700 cm−1 in return. Moreover, the lattice structures of BiFeO3 films are identified consequently on the basis of Raman spectroscopy. BiFeO3 films on SrRuO3 coated SrTiO3 (0 0 1) substrate, CaRuO3 coated SrTiO3 (0 0 1) substrate and tin-doped indium oxide substrate are found to be in the rhombohedral structure, while BiFeO3 film on SrRuO3 coated Nb: SrTiO3 (0 0 1) substrate is in the monoclinic structure. Our results suggest that polarized Raman spectroscopy would be a feasible tool to study the lattice structure of BiFeO3 films.  相似文献   

13.
Raman and infrared (IR) spectroscopy are complementary spectroscopic techniques. However, measurement of Raman and IR spectra are commonly carried out on separate instruments. A dispersive system that enables both Raman spectroscopy and NIR spectroscopy was designed, built, and tested. The prototype system measures spectral ranges of 2600–300 cm−1 and 752–987 nm for Raman and NIR channels, respectively. A wavelength accuracy better than 0.6 nm and spectral resolution better than 1 nm (14.4 cm−1 for Raman channel) could be achieved with our configuration. The linearity of spectral response was better than 99.8%. The intensity stability of the instrument was found to be 0.7% and 0.4% for Raman and NIR channels, respectively. The performance of the instrument was evaluated using binary aqueous solutions of ethanol and ovalbumin. It was found that ethanol concentrations (2–10%) could be predicted with a root mean squared error of prediction (RMSEP) of 0.45% using Raman peak height at 882.2 cm−1. Quantification of ovalbumin concentration (8–16 g/L) in aqueous solutions and in denatured states yielded RMSEP values of 1.05 g/L and 0.74 g/L, respectively. Using concentration as external perturbation in two-dimensional correlation spectroscopy (2DCOS), heterospectral correlation analysis revealed the relationship between NIR and Raman spectra.  相似文献   

14.
The data on the uranium metal corrosion rate in the solutions of nitric acid (0,1 – 4 M) and effect of complex forming agents on uranium corrosion properties are presented. The increase of HNO3 concentration caused the shift of corrosion potential from 38 mV to 446 mV and the increase of the corrosion rate from 0,02 to 0,62 mg.cm-2h-1. Transpassivation potential of U metal was found weakly effected by HNO3 concentration varying from 448 to 470 mV/Ag/AgCl. The addition of HCOOH to the electrolytes containing less than 3 M HNO3 found to shift the values of corrosion potentials about 500 mV towards negative direction reducing the passivation of U metal. The data on the kinetics of oxidative dissolution of PuO2 using Ag(II) and Am(VI,V) as mediators and the effect of the mediator generation techniques are discussed. The electrochemical properties of UC in the solutions 2 – 4 M HNO3, results of the quantitative determination of “oxidizable carbon” in dissolver solutions are presented. The results of corrosion and dissolution studies of Tc metal and Tc - Ru alloys containing from 19 to 70 at.% Ru in 0.5 0– 6 M HNO3 indicate the formation of passive films of Tc(IV) – Ru(III,IV) hydroxides at the electrode surface in the solutions containing less than 2 M HNO3 at the potentials less than 650 mV/Ag/AgCl. The increase of HNO3 concentration to values exceeding 3 M and the shift of the electrode potential towards positive direction causes the transition of the Tc and Tc-Ru alloys to transpassive state. The values of transpassivation potentials increase with the increasing with HNO3 concentration. Quantitative dissolution of Tc metal without application of oxidation potential becomes possible in the electrolytes, containing more than 4 M HNO3. The rate of Tc – Ru alloys dissolution is noticed to slow down with the increase of Ru content in the alloy.  相似文献   

15.
Olivine LiCoPO4 phase grown LiCoO2 cathode material was prepared by mixing precipitated Co3(PO4)2 nanoparticles and LiCoO2 powders in distilled water, followed by drying and annealing at 120 °C and 700 °C, respectively, for 5 h. As opposed to ZrO2 or AlPO4 coatings that showed a clearly distinguishable coating layer from the bulk materials, Co3(PO4)2 nanoparticles were completely diffused into the surface of the LiCoO2 and reacted with lithium of LiCoO2. An olivine LiCoPO4 phase was grown on the surface of the bulk LiCoO2, with a thickness of ∼7 nm. The electrochemical properties of the LiCoPO4 phase, grown in LiCoO2, had excellent cycle life performance and higher working voltages at a 1C rate than the bare sample. More importantly, Li-ion cells, containing olivine LiCoPO4, grown in LiCoO2, showed only 10% swelling at 4.4 V, whereas those containing bare sample showed a 200% increase during storage at 90 °C for 5 h. In addition, nail penetration test results of the cell containing olivine LiCoPO4, grown in LiCoO2 at 4.4 V, did not exhibit thermal runaway with a cell surface temperature of ∼80 °C. However, the cell containing bare LiCoO2 showed a burnt-off cell pouch with a temperature above 500 °C.  相似文献   

16.
Raman spectra of mineral peretaite Ca(SbO)4(OH)2(SO4)2·2H2O were studied, and related to the structure of the mineral. Raman bands observed at 978 and 980 cm?1 and a series of overlapping bands observed at 1060, 1092, 1115, 1142 and 1152 cm?1 are assigned to the SO42? ν1 symmetric and ν3 antisymmetric stretching modes. Raman bands at 589 and 595 cm?1 are attributed to the SbO symmetric stretching vibrations. The low intensity Raman bands at 650 and 710 cm?1 may be attributed to SbO antisymmetric stretching modes. Raman bands at 610 cm?1 and at 417, 434 and 482 cm?1 are assigned to the SO42? ν4 and ν2 bending modes, respectively. Raman bands at 337 and 373 cm?1 are assigned to O–Sb–O bending modes. Multiple Raman bands for both SO42? and SbO stretching vibrations support the concept of the non-equivalence of these units in the peretaite structure.  相似文献   

17.
《Vibrational Spectroscopy》2010,52(2):283-288
The far-infrared and Raman spectra of binuclear molecules [Me2AuX]2 (X = Cl, Br, I) and [Me2Au(OOCR)]2 (R = Me, CF3, But, Ph) in the 600–70 cm−1 region are reported. The experimentally measured vibrational frequencies of [Me2AuX]2 are in a good agreement with density functional theory predictions. The Au…Au vibrational interactions predicted to be in the 270–60 cm−1 region of [Me2AuX]2 far-IR and Raman spectra have been observed. The Raman-active Au…Au vibrations of the [Me2Au(OOCR)]2 molecules were found to be in the same region as those of [Me2AuX]2. The Au–X stretching modes were observed between 100 and 250 cm−1 in accordance with the DFT predictions. Their frequencies in the IR spectra of [Me2AuX]2 increase in the sequence I < Br < Cl while the AuC2 stretching frequencies decrease in the same order. This fact might be an evidence of the decreasing covalent character of the gold-halogen bridges. The Au–O stretching bands of dimethylgold(III) carboxylates have been observed in the 500–250 cm−1 region, and Au–C stretching frequencies of both [Me2AuX]2 and [Me2Au(OOCR)]2 compounds have been found between 600 and 500 cm−1.  相似文献   

18.
Raman spectra of coquandite Sb6O8(SO4)·(H2O) were studied, and related to the structure of the mineral. Raman bands observed at 970, 990 and 1007 cm?1 and a series of overlapping bands are observed at 1072, 1100, 1151 and 1217 cm?1 are assigned to the SO42? ν1 symmetric and ν3 antisymmetric stretching modes respectively. Raman bands at 629, 638, 690, 751 and 787 cm?1 are attributed to the SbO stretching vibrations. Raman bands at 600 and 610 cm?1 and at 429 and 459 cm?1 are assigned to the SO42? ν4 and ν2 bending modes. Raman bands at 359 and 375 cm?1 are assigned to O–Sb–O bending modes. Multiple Raman bands for both SO42? and SbO stretching vibrations support the concept of the non-equivalence of these units in the coquandite structure.  相似文献   

19.
We calculated IR, nonresonance Raman spectra and vertical electronic transitions of the zigzag single-walled and double-walled boron nitride nanotubes ((0,n)-SWBNNTs and (0,n)@(0,2n)-DWBNNTs). In the low frequency range below 600 cm−1, the calculated Raman spectra of the nanotubes showed that RBMs (radial breathing modes) are strongly diameter-dependent, and in addition the RBMs of the DWBNNTs are blue-shifted reference to their corresponding one in the Raman spectra of the isolated (0,n)-SWBNNTs. In the high frequency range above ∼1200 cm−1, two proximate Raman features with symmetries of the A1g (∼1355 ± 10 cm−1) and E2g (∼1330 ± 25 cm−1) first increase in frequency then approach a constant value of ∼1365 and ∼1356 cm−1, respectively, with increasing tubes’ diameter, which is in excellent agreement with experimental observations. The calculated IR spectra exhibited IR features in the range of 1200–1550 cm−1 and in mid-frequency region are consistent with experiments. The calculated dipole allowed singlet–singlet and triplet–triplet electronic transitions suggesting a charge transfer process between the outer- and inner-shells of the DWBNNTs as well as, upon irradiation, the possibility of a system that can undergo internal conversion (IC) and intersystem crossing (ISC) processes, besides the photochemical and other photophysical processes.  相似文献   

20.
The heat capacity of LiCoO2 (O3-phase), constituent material in cathodes for lithium-ion batteries, was measured using two differential scanning calorimeters over the temperature range from (160 to 953) K (continuous method). As an alternative, the discontinuous method was employed over the temperature range from (493 to 693) K using a third calorimeter. Based on the results obtained, the enthalpy increment of LiCoO2 was derived from T = 298.15 K up to 974.15 K. Very good agreement was obtained between the derived enthalpy increment and our independent measurements of enthalpy increment using transposed temperature drop calorimetry at 974.15 K. In addition, values of the enthalpy of formation of LiCoO2 from the constituent oxides and elements were assessed based on measurements of enthalpy of dissolution using high temperature oxide melt drop solution calorimetry. The high temperature values obtained by these measurements are key input data in safety analysis and optimisation of the battery management systems which accounts for possible thermal runaway events.  相似文献   

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