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1.
Abstract The ionic conductivity has been investigated in the Na 2SO 4 - Li 2SO 4 system for Na 2SO 4 concentrations larger than 50 mol%. In the solid solution of the high temperature phase of Na 2SO 4 the ionic conductivity increases with increasing Li 2SO 4 concentration in the whole concentration range. Thus both lithium and sodium ions contribute to the ionic transport. The ionic conductivity of the two-phase region existing at lower temperatures has also been investigated. 相似文献
2.
Inorganic-organic hybrid electrolytes were prepared by the mechanochemical method using the Li + ion conductive 70Li 2S·30P 2S 5 glass and various alkanediols. Local structure of the prepared electrolytes was analyzed by FT-IR and Raman spectroscopy. The effects of the proportion and chain length of alkanediols on conductivity of the hybrid electrolytes were investigated. The hybrid electrolyte with 2 mol.% of 1,4-butanediol exhibited the conductivity of 9.7 × 10 − 5 S cm − 1 at room temperature and the unity of lithium ion transference number. The use of alkanediols with shorter chain length was effective in increasing conductivity of hybrid electrolytes. The electrolyte using ethyleneglycol showed the highest conductivity of 1.1 × 10 − 4 S cm − 1 at room temperature. Lowering glass transition temperature by incorporation of alkanediols is responsible for the enhancement of conductivity of hybrid electrolytes. 相似文献
3.
Solid polymer electrolytes consisted of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend (50:50 wt/wt%) with lithium triflate (LiCF 3SO 3) as a dopant ionic salt at stoichiometric ratio [EO + (CO)]:Li + = 9:1, poly(ethylene glycol) (PEG) as plasticizer (10 wt%) and montmorillonite (MMT) clay as nanofiller (3 wt%) have been prepared by solution cast followed by melt–pressing method. The X–ray diffraction study infers that the (PEO–PMMA)–LiCF 3SO 3 electrolyte is predominantly amorphous, but (PEO–PMMA)–LiCF 3SO 3–10 wt% PEG electrolyte has some PEO crystalline cluster, whereas (PEO–PMMA)–LiCF 3SO 3–10 wt% PEG–3 wt% MMT electrolyte is an amorphous with intercalated and exfoliated MMT structures. The complex dielectric function, ac electrical conductivity, electric modulus and impedance spectra of these electrolytes have been investigated over the frequency range 20 Hz to 1 MHz. These spectra have been analysed in terms of the contribution of electrode polarization phenomenon in the low frequency region and the dynamics of cations coordinated polymer chain segments in the high frequency region, and also their variation on the addition of PEG and MMT in the electrolytes. The temperature dependent dc ionic conductivity, dielectric relaxation time and dielectric strength of the plasticized nanocomposite electrolyte obey the Arrhenius behaviour. The mechanism of ions transportation and the dependence of ionic conductivity on the segmental motion of polymer chain, dielectric strength, and amorphicity of these electrolytes have been explored. The room temperature ionic conductivity values of the electrolytes are found ∼10 −5 S cm −1, confirming their use in preparation of all-solid-state ion conducting devices. 相似文献
4.
The polyethylene oxide (PEO) based lithium ion conducting polymer electrolytes complexed with lithium trifluoromethanesulfonate (LiCF 3SO 3 or LiTf) plasticized with an ionic liquid 1-ethyl 3-methyl imidazolium trifluoromethanesulfonate (EMITf) have been reported. Morphological, spectroscopic, thermal and electrochemical investigations demonstrate promising characteristics of the polymer films, suitable as electrolyte in various energy storage/conversion devices. Significant structural changes have been observed in the polymer electrolyte due to the ionic liquid addition, investigated by X-ray diffraction (XRD) and optical microscopy. The ion-polymer interaction, particularly the interaction of imidazolium cation with PEO chains, has been evidenced by IR and Raman spectroscopic studies. The optimized composition of the polymer electrolyte i.e. PEO 25.LiTf + 40 wt.% EMITf offer room temperature ionic conductivity of ~ 3 × 10 − 4 S cm − 1 with wide electrochemical stability window and excellent thermal stability. The ‘σ versus 1/T’ curves show apparent Arrhenius behavior below and above melting temperature. The ionic conductivity has been observed due to Li + ions, as confirmed from 7Li-NMR studies, though the component ions of ionic liquid and anions also contribute significantly to the overall conductivity. 相似文献
5.
The electrical conductivity results of lithium borosilicate glasses with addition of Li 2SO 4 and LiCl have been critically analyzed. In general, it is observed that the factors viz. lithium fraction, f Li and the number of non-bridging oxygens (NBOs) govern the ionic conductivity in the lithium conducting glasses. For the same
f Li, the presence of mixed formers in the glass gives higher conductivity compared to that of the glass with only one former.
Thus the competitive network of glass in mixed former systems provides higher mobilities for lithium ions and hence high ionic
conductivity. The addition of Li 2SO 4 and LiCl in the lithium borosilicate glasses gave enhancement in the conductivity. However, the mechanism of enhancement
in conductivity is different in the two glass systems. The comparison of the result of binary, ternary and quaternary glass
systems suggests that in general, the decrease in activation energy, increase in f Li and increase in NBOs gives rise to enhancement in conductivity. For the same value of f Li the higher conductivity is exhibited by glasses with lower value of K (K=SiO 2/B 2O 3).
Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003. 相似文献
6.
The stability of aluminium oxide has been investigated in mixtures of ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF 4) and γ-butyrolactone (GBL) for application as the impregnation electrolyte of aluminium electrolytic capacitors. Ionic conductivity measurements of BMI.BF 4/GBL electrolytes at different temperatures were performed, as well as electrochemical impedance spectroscopy and cyclic voltammetry experiments. The results show that the highest ionic conductivity value of 40 mS cm ?1 (70 °C) is achieved in electrolyte x BMI.BF4 = 0.2. The total capacitance values, associated with the dielectric oxides, vary between 1 and 8 μF cm ?2 for all studied electrolytes after 30 days of immersion. The polarization resistance and total capacitance of the electrolyte/Al 2O 3/Al system decrease slightly with immersion time, showing the stability of Al 2O 3/Al in ionic liquid BMI.BF 4/GBL electrolytes. 相似文献
7.
Lithium salt, LiX (where X = BF 4 ? , I ?, CF 3SO 3 ? , COOCF 3 ? or ClO 4 ? ), was incorporated into epoxidized natural rubber (ENR). Thin films of LiX-ENR polymer electrolytes (PEs) were obtained via solvent casting method. These electrolytes were characterized using SEM/X-mapping, FTIR, differential scanning calorimeter, thermogravimetry analysis, and impedance spectroscopy. The trend in thermal stability and ionic conductivity of LiX-ENR PEs follow LiBF 4 > > LiCF 3SO 3 ~ LiCOOCF 3 > LiI > > LiClO 4. The LiClO 4 hardly dissociates and formed LiClO 4 aggregates within the polymer matrix that resulted in a PE with low thermal stability and low ionic conductivity. The LiCF 3SO 3, LiCOOCF 3, and LiI, however, exert moderate interactions with the ENR, and their respective PEs exhibit moderate ionic conductivity and thermal property. The occurrence of epoxide ring opening and complexation or cross-linking reactions in and between the ENR chains that involve BF 4 ? ions have produced a LiBF 4-ENR PE with superior thermal property and ionic conductivity as compared to other PEs studied in this work. 相似文献
8.
我们用Raman光谱研究了Li 2O(LiCl) 2B 2O 3-Al 2O 3系玻璃的结构,着重研究了Al 2O 3的影响。对于Li 2O-B 2O 3系玻璃,Li 2O含量增加使玻璃中存在的BO 3三角体转变为BO 4四面体,
关键词: 相似文献
9.
Thin film of poly (vinylchloride) and poly (methylmethacrylate) blend polymer electrolytes plasticized with a combination
of DBP and Li 2SO 4 salts have been prepared by solution casting technique. The prepared films were subjected to a.c. impedance measurements
as a function of temperature ranging from 304–373 K. The maximum conductivity at 304 K was found to be 1.24 × 10 −8 S·cm −1 for PVC-PMMA-Li 2SO 4-DBP (7.5-17.5-5-70 mole-%). Temperature dependence studies on the ionic conductivity in the PVC-PMMA-Li 2SO 4-DBP system suggest that the ion conduction follows the Williams-Landel-Ferry (WLF) mechanism, which is further confirmed
by Vogel-Tamman-Fulcher (VTF) plots. XRD, FTIR, SEM and thermal studies revealed complex formation in. 相似文献
10.
Electrical and electrochemical properties of the 70Li 2S·(30 − x)P 2S 5·xP 2S 3 and the 70Li 2S·(30 − x)P 2S 5·xP 2O 5 (mol%) glass-ceramics prepared by the mechanical milling technique were investigated. Glass-ceramics with 1 mol% P 2S 3 and 3 mol% P 2O 5 showed the highest conductivity of 5.4 × 10 − 3 S cm − 1 and 4.6 × 10 − 3 S cm − 1, respectively. Moreover, these glass-ceramics showed higher electrochemical stability than the 70Li 2S·30P 2S 5 (mol%) glass-ceramic. From the XRD patterns of the obtained glass-ceramics, trivalent phosphorus and oxygen were incorporated into the Li 7P 3S 11 crystal. We therefore presume that the Li 7P 3S 11 analogous crystals, which were formed by incorporating trivalent phosphorus and oxygen into the Li 7P 3S 11 crystal, improve the electrical and electrochemical properties of the glass-ceramics. An all-solid-state cell using the 70Li 2S·29P 2S 5·1P 2S 3 (mol%) glass-ceramic as solid electrolyte operated under the high current density of 12.7 mA cm − 2 at the high temperature of 100 °C. The cell showed an excellent cyclability of over 700 cycles without capacity loss. 相似文献
11.
本文通过对 11B核磁共振( 11B-NMR)、红外光谱等实验方法,研究了LiF-LiCl-B 2O 3三元系统玻璃的结构和离子导电性,着重于F -离子在玻璃网络中所起的作用,以及F -,Cl -和Li +离子对导电率的影响。LiF-LiCl-B 2O 3三元系统玻璃,随LiF含量的增加,B由三角体向四面体变化,从而F -离子进入网络,使玻璃结构由[B 2O 3]三角体层状结构向三维空间延展,形成了含有[BO 3F]基团的三维空间网络,Cl -离子以游离的离子存在于网络中,起着松散网络的作用,对提高电导率有利,而Li +离子作为传导离子,对电导率的贡献是主要的。本系统玻璃的电导率是随LiF,LiCl含量的增加而增大,在300℃时测得电导率σ=6.12×10 -4Ω -1·cm -1。
关键词: 相似文献
12.
A solid polymer electrolyte (SPE) is synthesized by solution casting technique. The SPE uses poly(ethylene oxide) PEO as a host matrix doped with lithium triflate (LiCF 3SO 3), ethylene carbonate (EC) as plasticizer and nano alumina (Al 2O 3) as filler. The polymer electrolytes are characterized by Impedance Spectroscopy (IS) to determine the composition of the additive which gives the highest conductivity for each system. At room temperature, the highest conductivity is obtained for the composition PEO-LiCF 3SO 3-EC-15%Al 2O 3 with a value of 5.07 10 − 4 S/cm. The ionic conductivity of the polymer electrolytes increases with temperature and obeys the Arrhenius law. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) studies indicate that the conductivity increase is due to an increase in amorphous content which enhances the segmental flexibility of polymeric chains and the disordered structure of the electrolyte. Fourier transform infrared spectroscopy (FTIR) spectra show the occurrence of complexation and interaction among the components. Scanning electron microscopy (SEM) images show the changes morphology of solid polymer electrolyte. 相似文献
13.
Solid polymer electrolytes based on polyacrylonitrile (PAN) doped with ammonium thiocyanate (NH 4SCN) in different molar ratios of polymer and salt have been prepared by solution-casting method using DMF as solvent. The increase in amorphous nature of the polymer electrolytes has been confirmed by XRD analysis. A shift in glass transition temperature ( T g) of the PAN?:?NH 4SCN electrolytes has been observed from the DSC thermograms which indicates the interaction between the polymer and the salt. From the AC impedance spectroscopic analysis, the ionic conductivity has been found to increase with increasing salt concentration up to 30 mol% of NH 4SCN beyond which the conductivity decreases and the highest ambient temperature conductivity has been found to be 5.79?×?10 ?3 S cm ?1. The temperature-dependent conductivity of the polymer electrolyte follows an Arrhenius relationship which shows hopping of ions in the polymer matrix. The dielectric loss curves for the sample 70 mol% PAN?:?30 mol% NH 4SCN reveal the low-frequency β-relaxation peak pronounced at high temperature, and it may be caused by side group dipoles. The ionic transference number of polymer electrolyte has been estimated by Wagner’s polarization method, and the results reveal that the conductivity species are predominantly ions. 相似文献
14.
Nano-composite polymer gel electrolytes were synthesized by using polyethylene oxide (PEO), ammonium tetrafluoroborate (NH4BF4), fumed silica (SiO2), dimethylacetamide (DMA), ethylene carbonate (EC), and propylene carbonate (PC) and characterized by conductivity studies. The effect of donor number of solvent on ionic conductivity of polymer gel electrolytes has been studied. The mechanical strength of the gel electrolytes has been increased with the addition of nano-sized fumed silica along with an enhancement in conductivity. Maximum room temperature ionic conductivity of 2.63 × 10−3 and 2.92 × 10−3 S/cm has been observed for nano-composite gel electrolytes containing 0.1 and 0.5 wt% SiO2 in DMA+1 M NH4BF4+10 wt% PEO, respectively. Nano-composite polymer gel electrolytes having DMA have been found to be thermally and electrically stable over 0 to 90 °C temperature range. Also, the change in conductivity with the passage of time is very small, which may be desirable to make applicable for various smart devices. 相似文献
15.
Poly(squarate)s ( PPS- 1 and PPS- 2) were synthesized by the reaction of squaryl dichloride with hydroquinone for PPS- 1 and with 2,5-diethoxy-1,4-bis(trimethylsilyloxy)benzene for PPS- 2, and the ionic conductivities, thermal properties, and electrochemical and thermal properties of their polymer electrolytes
with LiN(CF 3SO 2) 2 were investigated. The ionic conductivity increased with increasing the lithium salt concentration for the PPS- 1–LiN(CF 3SO 2) 2 electrolyte, and the highest ionic conductivities of 8.60 × 10 −5 S/cm at 100 °C and 9.57 × 10 −8 S/cm at 30 °C were found at the [Li] to [O] ratio of 2:1. And also, the ionic conductivity for the PPS- 1–LiN(CF 3SO 2) 2 electrolyte increased with an increase in the lithium salt concentration, reached a maximum value at the [Li] to [O] ratio
of 1:2, and then decreased. The highest ionic conductivity was to be 1.04 × 10 −5 S/cm at 100 °C and 1.71 × 10 −8 S/cm at 30 °C, respectively. Both polymer electrolytes exhibited relatively better electrochemical and thermal stabilities.
Addition of the PPS- 1 as a plasticizer into the poly(ethylene oxide) (PEO)–LiN(CF 3SO 2) 2 electrolyte system suppressed the crystallization of PEO, and improved the ionic conductivity at room temperature.
Invited paper dedicated to Professor W. Weppner on his 65th birthday. 相似文献
16.
High quality solid electrolyte thin films was grown by pulsed laser deposition (PLD) using a high photon energy ArF excimer laser. Various amorphous thin films were successfully deposited on glass substrates from oxide targets; such as Li 3PO 4, LiBO 2, Li 2SiO 3, Li 2CO 3, Li 2SO 4, Li 2ZrO 3, LiAlO 2, Li 2WO 4 and Ohara glass ceramics. The morphology, optical property and ionic conductivity of these films were examined by optical microscope, UV–VIS spectroscopy and impedance analysis. Dramatic improvement of the film morphology was observed by using a high photon energy laser, while the broken film with many droplets was obtained by using lower ones. Ionic conductivity of the films was examined by impedance spectroscopy and dc polarization method. For example, an ionic conductivity of a Li 3PO 4 film was 4.6 × 10 ? 6 S cm ? 1 at 25 °C with activation energy of 0.57 eV. Electronic conductivity measurements revealed that most of the films were pure lithium ion conductors, while a Li 2WO 4 film was a mixed conductor. 相似文献
17.
Poly(4-vinylbenzeneboronic acid), PVBBA was synthesized via free-radical polymerization of 4-vinylbenzeneboronic acid (4-VBBA) and followed by crosslinking with polyethylene glycol (PEG) with different molecular weights to produce boron containing crosslinked polymers. Prior to crosslinking, the materials were doped with CF 3SO 3Li at several stoichiometric ratios to get PVBBAPEGX-Y where X is the molecular weight of PEG and Y is the EO/Li ratio. The materials were characterized by using Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and differential scanning calorimeter (DSC). The ionic conductivity of these novel crosslinked electrolytes was studied by dielectric-impedance spectroscopy. Li-ion conductivity of these polymer electrolytes depends on the length of the side units as well as the doping ratio. PVBBAPEG200-10 illustrated a satisfactory ionic conductivity of 3.1 × 10 ?5 S/cm at 20 °C and 1.8 × 10 ?3 S/cm at 100 °C. 相似文献
18.
Polymer blend electrolytes based on poly(ethylene oxide) (PEO) and poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) were prepared by using different lithium salts LiX (X = ClO 4, BF 4, CF 3SO 3, and N [CF 3SO 2] 2) using solution casting technique. To confirm the structure and complexation of the electrolyte films, the prepared electrolytes were subjected to X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis. Alternating current (AC) impedance analysis was performed for all the electrolyte samples at various temperatures from 303 to 343 K. The result suggests that among the various lithium salts, LiN[CF 3SO 2] 2-based electrolytes exhibited the highest ionic conductivity at 8.20 × 10 ?4 S/cm. The linear variation of the ionic conductivity of the polymer electrolytes with increasing temperature suggests the Arrhenius-type thermally activated process. Activation energies were found to decrease when doping with lithium imide salt. The dielectric behavior has been analyzed using dielectric permittivity ( ε*), electric modulus (M*), and dissipation factor (tan δ) of the samples. Cyclic voltammetry has been performed for the electrolyte films to study their cyclability and reversibility. Thermogravimetric and differential thermal analysis (TG/DTA) was used to ascertain the thermal stability of the electrolytes, and the porous nature of the electrolytes was identified using scanning electron microscopy via ion hopping conduction. Surface morphology of the sample having maximum conductivity was studied by an atomic force microscope (AFM). 相似文献
19.
A new series of gel polymer electrolytes (GPEs) based on an optimized composition of polymer blend-salt matrix [poly(vinyl chloride) (PVC) (30 wt%) / poly(ethyl methacrylate) (PEMA) (70 wt%): 30 wt% zinc triflate Zn(CF 3SO 3) 2] containing different concentrations of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide (EMIMTFSI) ionic liquid has been prepared by simple solution casting technique. The prepared films of gel polymer membranes have been characterized utilizing complex impedance spectroscopy, differential scanning calorimetry (DSC), thermogravimetric (TG), and cyclic voltammetry (CV) analyses. The dielectric constant and ionic conductivity pursue similar trend with increasing EMIMTFSI concentration. The addition of ionic liquid in varied amounts into the optimized polymer blend-salt system effectively reduces the glass transition temperature ( Tg) of the film as revealed from differential scanning calorimetry results. The origin of an improved thermal stability and feasible cyclic performance in respect of the best conducting sample of the resultant gel polymer electrolytes was also examined by utilizing thermogravimetric and cyclic voltammetry measurements. 相似文献
20.
Proton-conducting polymer complex electrolytes were prepared by incorporation of boric acid, H 3BO 3 into poly(vinylalcohol), PVA, to form hydrated PVA xH 3BO 3 where x denotes the number of moles of boric acid per polymer repeat unit. The dried materials were characterized via Fourier transform
infrared spectroscopy, thermogravimetry, and X-ray diffraction. The proton conductivity of the hydrated complex electrolytes
was measured by AC impedance spectroscopy. PVA2H 3BO 3 with RH ∼25% was found to be optimum composition that exhibited proton conductivity of 1.3 × 10 −3 S/cm at 80 °C. 相似文献
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