Effect of ZrO2 on conductivity of PVC-PMMA-LiBF4-DBP polymer electrolytes

The preparation and characterization of composite polymer electrolytes of PVC-PMMA-LiBF₄-DBP for different concentrations of ZrO₂ have been investigated. FTIR studies indicate complex formation between the polymers, salt and plasticizer. The electrical conductivity values measured by a.c. impedance spectroscopy is found to depend upon the ZrO₂ concentration. The temperature dependence of the conductivity of the polymer films seems to obey the VTF relation. The conductivity values are presented and results discussed.     

(PEG) x NH4ClO4: a new polymeric fast proton conductor

A new polymer electrolyte (PEG) _x NH₄ClO₄(x = 5, 10, 15, 20) has been prepared that shows protonic conduction. The room temperature conductivities are of the order of 10⁻⁷S/cm, and increase with decrease in salt concentration. NMR line width studies indicate fairly low glass transition temperatures of the polymer salt complexes. Paper presented at the poster session of MRSI AGM VI. Kharagpur, 1995     

Al4B2O9纳米棒改性制备优异综合性能的固体聚合物电解质

随着储能设备和电力驱动产品的激增,特别是电动汽车的大规模推广应用,全固态电池被认为是最有可能解决电动设备日益严峻的安全问题和高能量密度需求的策略之一.本文报道了一种Al4B2O9纳米棒改性的聚环氧乙烷(PEO)基固体聚合物电解质(ASPE),其具有高离子电导率、宽电化学窗口、良好的机械性能和阻燃性能.具体来说,因为Al...     

锂离子电池聚氨酯型凝胶态聚合物电解质的研究

采用一种自制新型超支化聚醚(PHEMO)与甲苯2,4-二异氰酸酯(MDI)在电解液中进行缩合反应,制备了一种具有交联网状结构的聚氨酯(PEU)型凝胶态聚合物电解质.利用傅立叶红外光谱(FTIR)、示差扫描量热分析(DSC)、热重分析(TGA)、交流阻抗谱等测试方法对聚合物电解质的结构、热稳定性能、离子电导率进行了研究.研究发现:上述制备的PM-1M-Z4聚合物电解质体系室温电导率可达2.53×10-3S/cm,电化学稳定窗口为2.3～4.0V,并且具有较好的热稳定性和优良的机械性能.此外,在这种新型的电解质中,电解液小分子被聚合物大分子包裹在其中,可有效防止凝胶聚合物电解质的漏液问题,从而可提高锂离子电池的安全性能.     

锂离子电池用固态偏氟乙烯-六氟丙烯共聚物电解质的研究进展

固体聚合物电解质具有质轻、安全、易加工等优点,在锂离子电池中具有极大的应用价值.综述了以偏氟乙烯-六氟丙烯(PVDF-HFP)共聚物为基的聚合物电解质的研究工作,介绍了PVDF-HFP固体电解质的制备方法,分析了影响此聚合物电解质性能的因素,并讨论了PVDF-HFP电解质的改性措施,对今后的发展方向作了简要展望.     

Morphology and conductivity studies of a new solid polymer electrolyte: (PEG)<Subscript>x</Subscript>LiClO<Subscript>4</Subscript>

A new solid polymer electrolyte, (PEG)_xLiClO₄, consisting of poly(ethylene)glycol of molecular weight 2000 and LiClO₄ was prepared and characterized using XRD, IR, SEM, DSC, NMR and impedance spectroscopy techniques. XRD and IR results show the formation of the polymer-salt complex. The samples with higher salt concentration are softer, less opaque and less smooth compared to the low salt concentration samples. DSC studies show an increase in the glass transition temperature and a decrease in the degree of crystallinity with increase in the salt concentration. Melting temperature of SPEs is lower than the pure PEG 2000. Room temperature¹H and⁷Li NMR studies were also carried out for the (PEG)_xLiClO₄ system. The¹H linewidth decreases as salt concentration increases in a similar way to the decrease in the crystalline fraction and reaches a minimum at aroundx = 46 and then increases.⁷Li linewidth was found to decrease first and then to slightly increase after reaching a minimum atx = 46 signifying the highest mobility of Li ions for this composition. Room temperature conductivity first increases with salt concentration and reaches a maximum value (σ = 7.3 × 10⁻⁷ S/cm) atx = 46 and subsequently decreases. The temperature dependence of the conductivity can be fitted to the Arrhenius and the VTF equations in different temperature ranges. The ionic conductivity reaches a high value of ∼10 ⁻⁴S/cm close to the melting temperature.     

Glowing Combustion Synthesis,Characterization, and Toxicity Studies of Na2CaSiO4 Powders

Here, we are reporting the glowing combustion synthesis of Na₂CaSiO₄ powders for the first time at low temperature. L-alanine was used as reductant, and nitrates of sodium and calcium were used as oxidants. Phase evolution and formation was studied using X-ray diffraction (XRD), Fourier transform infrared (FTIR), Thermo gravimetric analysis-Differential thermal analysis (TGA–DTA) techniques. Powder morphology and particle size distribution were characterized using scanning electron microscopy (SEM), dynamic light scattering (DLS) techniques. Results confirms the formation of single phasic, microcrystalline sodium calcium silicate (Na₂CaSiO₄ phase) in cubic crystal system. Evaluation of hemolysis and (3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide) (MTT) tests suggest that Na₂CaSiO₄ powders exhibit negative response in in vitro conditions.     

Characterization of nano-crystalline LiNiVO4 synthesized by hydrothermal process

LiOH·H₂O, Ni(CH₃COO)₂·4H₂O and NH₄VO₃ were used to synthesize nano-crystalline LiNiVO₄ by hydrothermal process in deionized water at 150 °C for 2 h and subsequent calcination at 300-600 °C for 6 h. By using an X-ray diffractometer (XRD), a transmission electron microscope (TEM) and a selected area electron diffraction (SAED) method, nano-crystalline LiNiVO₄ with inverse spinel structure was detected. The stretching vibration of VO₄ tetrahedrons analyzed by a Fourier transform infrared spectrometer (FTIR) was split into three bands at 661, 746 and 835 cm^− 1, and that analyzed by a Raman spectrometer was detected at 823.9 and 787.7 cm^− 1. The thermogravimetric and differential thermal analyses (TGA and DTA) show two discrete weight losses at 25-117 °C and 117-600 °C and four endothermic peaks at 84, 145, 202 and 372 °C, corresponding to the evaporation of water and the decomposition of inorganic and organic compounds.     

Characterization of MMoO4 (M = Ba, Sr and Ca) with different morphologies prepared using a cyclic microwave radiation

Scheelite molybdates (MMoO₄, M = Ba, Sr and Ca) were successfully prepared by the reactions of M(NO₃)₂·2H₂O and Na₂MoO₄·2H₂O in propylene glycol and NaOH using a microwave radiation. The phases were detected using XRD and SAED. TEM analysis revealed the presence of micro-sized bi-pyramids with a square base, nano-sized particles in clusters, and dispersed nano-sized particles for BaMoO₄, SrMoO₄ and CaMoO₄, respectively. Diffraction patterns of the bi-pyramids were simulated, and are in accord with the experimental results. Raman and FTIR spectra provide the evidence of scheelite structure with Mo-O stretching vibration in MoO₄²⁻ tetrahedrons at 742-901 cm^− 1.     

A structural supercapacitor based on activated carbon fabric and a solid electrolyte

ABSTRACT

This paper presents investigations to create a structural supercapacitor with activated carbon fabric electrodes and a solid composite electrolyte, consisting of organic liquid electrolyte 1?M TEABF₄ in propylene carbonate and an epoxy matrix where different compositions were considered of 1:2, 1:1 and 2:1 w/w epoxy:liquid electrolyte. Vacuum-assisted resin transfer moulding was used for the impregnation of the electrolyte mixture into the electrochemical double layer capacitor (EDLC) assembly. The best electrochemical performance was exhibited by the 1:2 w/w epoxy: liquid electrolyte ratio, with a cell equivalent-in-series resistance of 160?Ω?cm² and a maximum electrode-specific capacitance of 101.6?mF?g^?1 while the flexural modulus and strength were 0.3?GPa and 29.1?MPa, respectively, indicating a solid EDLC device.     

碳芯结构LiFePO_4/C复合材料的表征及电化学性能

采用环氧树脂为碳源制备出碳芯结构LiFePO4/C复合材料.利用X射线衍射、扫描电镜、透射电镜和X光电子能谱等分别对复合材料的晶体结构、表面形貌及表面成分进行表征,采用恒电流充放电和电化学阻抗方法研究试样的电化学性能.实验结果表明:碳芯结构复合材料是由无定形碳线和纳米LiFePO4颗粒组成.碳芯结构LiFePO4/C复合材料在15mA/g的电流密度下,首次放电容量达到166mAh/g,当电流密度增加到750mA/g,放电容量高达131mAh/g,经过50次循环后,容量保持率高达99.2%.     

聚离子液体型聚合物电解质的制备及表征

以N-乙烯基咪唑、溴乙酸甲酯和二（三氟甲基磺酰亚胺）锂（LiTFSI）为原料,采用溶液聚合法制备了聚（1-乙烯基-3-乙酸甲酯基咪唑二（三氟甲基磺酰亚胺））（PMVIm-TFSI）。将其与LiTFSI和聚（甲基丙烯酸甲酯-醋酸乙烯酯）（P（MMA-VAc））共混制得了不同质量比的聚合物电解质。核磁共振（1 HNMR）、红外光谱（FT-IR）、示差扫描量热计（DSC）、热重分析（TGA）、X射线衍射（XRD）、扫描电镜（SEM）、交流阻抗（AC impedance）等对电解质的测试结果表明,PMVIm-TFSI掺杂到P（MMA-VAc）和LiTFSI组成的电解质中后其电导率得到了极大的改善,30℃下最高可达4.71×10-4S/cm,同时热稳定性也得到了极大的提高。此外,该共混电解质（透过率≥90%）还可以运用到电致变色器件（ECD）导电离子材料中,也显示出了优良的电化学性能。     

Structural,thermal and electrical properties of plasticised PVA based polymer electrolyte

Polymer electrolyte films of polyvinyl alcohol as host polymer, poly(3,4-etylenedioxythiophene)/poly(styrenesulphonate), magnesium bromide were prepared using solution cast technique. Succinonitrile was used as plasticiser in the matrix at different concentrations. These films were characterised using thermogravimetric analysis, X-ray diffraction and ac impedance spectroscopy. The conductivity measurement was used to determine the ionic conductivity of the polymer electrolyte at different temperature and frequency values, giving some insight into its potential utility as a solid membrane in solid state batteries. The ionic transference number of mobile ions has been estimated by a dc polarisation method, and the results reveal that the conducting species are predominately ions. A solid state magnesium battery was fabricated and characterised.     

Influence of activated polymer on the etching rate of silicon in CF4+H2 plasma

The reactive ion etching (RIE) of silicon in CF₄+H₂ plasma is considered. The influence of activated polymer on the RIE rate of silicon in CF₄+H₂ plasma is determined by extrapolation of experimentally measured kinetics of the etching rate. It is found that increased adsorption of CF₂ radicals suppresses the RIE rate of silicon in CF₄+H₂ plasma during the initial stages of the etching process. The formation of activated polymer becomes pronounced when adsorbed CF₂ radicals are slowly activated. The activated polymer intensifies the etching reaction and enhances the etching rate. C atoms, produced during the reaction, contribute to the formation of polymer on the surface. The increased concentration of the polymer suppresses the RIE rate of silicon in CF₄+H₂ plasma at later stages of the etching process.     

Spray-pyrolysis Cd2SnO4 films for electrochemical applications

Conductive cadmium stannate (Cd₂SnO₄,) films were grown by a simple spray-pyrolysis technique using aerosols ultrasonically generated from solutions containing Cd(thd)₂(TMEDA) and ⁿBu₂Sn(AcAc)₂, and monoglyme as solvent (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate, TMEDA = N,N,N′,N′-tetramethylethylenediamine, AcAc = acethylacetonate). The overall film growing procedure was carried out at or below 400 °C thus allowing low-melting temperature materials like glass to be used as film substrates. Typical resistivity values of Cd₂SnO₄ films were found to be ∼ 2 · 10 ⁻³ Ωcm. The films exhibit excellent electrochemical activity with comparable or higher electron transfer rates than cadmium stannate films obtained via sol-gel methods at high annealing temperature.     

Conductivity behaviour of polymer gel electrolytes: Role of polymer

Polymer is an important constituent of polymer gel electrolytes along with salt and solvent. The salt provides ions for conduction and the solvent helps in the dissolution of the salt and also provides the medium for ion conduction. Although the polymer added provides mechanical stability to the electrolytes yet its effect on the conductivity behaviour of gel electrolytes as well as the interaction of polymer with salt and solvent has not been conclusively established. The conductivity of lithium ion conducting polymer gel electrolytes decreases with the addition of polymer whereas in the case of proton conducting polymer gel electrolytes an increase in conductivity has been observed with polymer addition. This has been explained to be due to the role of polymer in increasing viscosity and carrier concentration in these gel electrolytes.     

In-situ FTIR studies of the growth of vanadium dioxide coatings on glass by atmospheric pressure chemical vapour deposition for VCl4 and H2O system

This paper describes the use of in-situ FTIR to monitor the growth of VO₂ thin films on SiO₂-precoated glass from VCl₄ and H₂O under APCVD conditions. It is shown that the amount of H₂O introduced during the various reaction conditions can affect the intensity of HCl only in high excess. This observation is attributed to the operation of a possible surface reaction mechanism. The data presented here also suggest that the direct monitoring of the HCl bands might be an excellent process of providing a method of process control.     

Crystallinity, magnetic and electrochemical studies of PVDF/Co3O4 polymer electrolyte

Organic-inorganic nanocomposites are gaining importance in the recent times as polymer electrolyte membranes. In the present work, composites were prepared by combining nano sized Co₃O₄ and poly(vinyledene fluoride) (PVDF), using spin coating technique. The surface of the PVDF/Co₃O₄ system characterized through field emission scanning electron microscopy (FESEM) revealed a porous structure of the films. The nanoparticles tend to aggregate on the surface and inside the pores, leading to a decrease in the porosity with an increase in Co₃O₄ content. Co₃O₄ nanoparticles prohibit crystallization of the polymer. Differential scanning calorimetry (DSC) studies revealed a decrease in crystallinity of PVDF/Co₃O₄ system with an increase in the oxide content. Magnetic property studies of the composite films revealed that with an increase in Co₃O₄ content, the saturation magnetization values of the nanocomposites increased linearly, showing successful incorporation of the nanoparticles in the polymer matrix. Further, ionic conductivity of the composite films was evaluated from electrochemical impedance spectroscopy. Addition of Co₃O₄ nanoparticles enhanced the conductivity of PVDF/Co₃O₄ system.     

Excellent visible light photocatalytic properties of novel graphene based CdLa2S4/TiO2 heterojunction nanocomposite

This paper introduced one pot method for the synthesis of hybrid CdLa₂S₄-graphene/TiO₂ nanocomposite. The surface properties seen by SEM present a characterization of the texture on CdLa₂S₄-graphene/TiO₂ composites and showed a homogenous composition in the particles. The EDX spectra for the elemental identification showed the presence of C, O and Ti with strong Cd, La and S peaks for the CdLa₂S₄-graphene/TiO₂ nanocomposite. The generation of reactive oxygen species were detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). It is found that the photocurrent density and the photocatalytic effect increase in the case with the modified CdLa₂S₄.From the photocatalytic results, the excellent activity of CdLa₂S₄-graphene/TiO₂ nanocompositefor degradation of methylene blue (MB) and Texbrite BA-L (TBA) undervisible irradiation could be attributed to both the effects between photocatalysis of the supported TiO₂ and charge transfer of the grapheme nanosheet, and the introduction of CdLa₂S₄ to enhance the photogenerated electrons.