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- Bayrak Pehlivan, Ilknur, et al.
(author)
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Ion conduction of branched polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide electrolytes
- 2011
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In: Electrochimica Acta. - : Elsevier BV. - 0013-4686 .- 1873-3859. ; 57, s. 201-206
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Journal article (peer-reviewed)abstract
- Ionic conductivity of polymer electrolytes containing branched poly (ethylene imine) (BPEI) and lithium bis(trifluoromethyl sulfonyl)imide (LiTFSI) was measured between temperatures of 20 and 70◦C and molar ratios of 20:1 and 400:1. The electrolytes were characterized by impedance spectroscopy, differential scanning calorimetry, and viscosity measurements. At room temperature, the maximum conductivity was 2×10−6 S/cm at a molar ratio of 50:1. The molar conductivity of the electrolytes displayed first a minimum and then a maximum upon increasing salt concentration. A proportionality of molar conductivity to segmental mobility was seen from glass transition temperature and viscosity measurements. Analysis of the Walden product and isoviscosity conductivity showed that the percentage of ions bound in ion pairs increased at low concentrations below 0.1 mol/kg. The average dipole moment decreased with salt concentration. The temperature dependence of the ionic conductivity showed an Arrhenius behavior.
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- Bayrak Pehlivan, Ilknur, et al.
(author)
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[PEI-SiO2]:[LiTFSI] nanocomposite polymer electrolytes : Ion conduction and optical properties
- 2012
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In: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 98, s. 465-471
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Journal article (peer-reviewed)abstract
- Ion conductivity and optical properties were investigated for polymer electrolytes based on poly (ethyleneimine) and lithium bis(trifluoromethylsulfonyl)imide and also containing up to 9 wt.% of 7-nm-diameter SiO2 nanoparticles. The [N]:[Li] molar ratio was kept constant at 50:1. Impedance measurements were performed in the frequency range 10(-2)-10(7) Hz and between the temperatures 20 and 70 degrees C with an applied ac voltage of 1 V. Spectrophotometric data of total and diffuse transmittance were taken between the wavelengths 300 and 2500 nm. The bulk impedance was fitted to a conductive Havriliak-Negami circuit model. The ion conductivity increased monotonically for increasing SiO2 contents: specifically its room temperature value went from 8.5 x 10(-7) S/cm without nanoparticles to 3.8 x 10(-5) S/cm for 8 wt.% of SiO2 while the diffuse transmittance remained at similar to 1% so that optical clarity prevailed.
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- Granqvist, Claes Göran, et al.
(author)
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Electrochromic foil-based devices : Optical transmittance and modulation range, effect of ultravioled irradiation, and quality assessment by 1/f current noise
- 2008
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In: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 516:17, s. 5921-5926
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Journal article (peer-reviewed)abstract
- We introduce electrochromic (EC) technology for modulating the transmittance of visible light and solar radiation in window apertures, with focus on recent work on foil-type devices embodying sputter deposited WO3 and NiO films joined by a polymer electrolyte. The purpose of this paper is to present a number of new and preliminary results showing that (i) double-sided antireflection coatings based on dip coating can enhance the transmittance significantly, (ii) tandem foils can yield a ratio between bleached-state and colored-state transmittance exceeding fifty, (iii) solar irradiance onto the EC device can enhance its charge insertion dynamics and thereby its optical modulation, and (iv) electromagnetic noise spectroscopy may serve as quality assessment of EC devices.
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- Marsal, Roser
(author)
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Early water management systems on the southern Transjordan plateau
- 2023
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In: Journal of Archaeological Science. - : Elsevier. - 2352-409X .- 2352-4103. ; 47
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Journal article (peer-reviewed)abstract
- The efficient management of water resources to supply the needs of societies in territories where water is a scarce and limited resource has been essential throughout time. The site of Sela on the southern Transjordan plateau is unique for understanding water management in this semi-arid area. The analysis of hydraulic installations has allowed us to characterise its hydro technology and spatial distribution in the settlement. To this end, the hy-draulic facilities have been identified, documented, and analysed in detail through two archaeological surveys (2015 and 2016). Spatial analysis has been carried out by preparing extensive 2D planimetry and 3D re-constructions. The results obtained have made it possible to reconstruct the water supply system necessary for the subsistence of the societies that inhabited Sela over time. The system consists of canals, cisterns, and sedi-mentation basins for the collection, conduction, storage, and preservation of water, mainly from rain. Some of Sela's hydraulic structures may have originated in the Bronze Age (mid-late 2nd mill. BCE), but more secure dating is needed to substantiate this possibility.
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- Pehlivan, Ilknur Bayrak, et al.
(author)
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Ionic relaxation in polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide polymer electrolytes
- 2010
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 108:7, s. 074102-
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Journal article (peer-reviewed)abstract
- Polymer electrolytes containing polyethyleneimine and different concentrations of lithium bis(trifluoromethylsulfonyl) imide were investigated by impedance spectroscopy at different temperatures. Two equivalent circuit models were compared for the bulk impedance response. The first one includes a conductive Havriliak-Negami (HN) element which represents ionic conductivity and ion pair relaxation in a single process, and the second model includes a dielectric HN element, which represents ion pair relaxation, in parallel with ion conductivity. Comparison of the two circuit models showed that the quality of the fit was similar and in some cases better for the conductive model. The experimental data follow the Barton-Nakajima-Namikawa relation, which relates the ion conductivity and the parameters of the relaxation. This indicates that ion conductivity and ion pair relaxation are two parts of the same process and should be described by the conductive model.
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- Pehlivan, Ilknur Bayrak, et al.
(author)
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PEI-LiTFSI electrolytes for electrochromic devices : Characterization by differential scanning calorimetry and viscosity measurements
- 2010
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In: Solar Energy Materials and Solar Cells. - : Elsevier BV. - 0927-0248 .- 1879-3398. ; 94:12, s. 2399-2404
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Journal article (peer-reviewed)abstract
- Polymer electrolytes containing poly(ethylene imine) (PEI) and lithium bis(trifluoromethylsulfonyl) imide (LiTFSI) can serve as model electrolytes for electrochromic devices. Such electrolytes were characterized by differential scanning calorimetry, conductivity, and viscosity measurements. The glass transition temperature (T-g) and viscosity of the PEI-LiTESI electrolytes have minima at a [N]:[Li] ratio of 100:1. Both T-g and viscosity increased at high salt concentrations. The temperature dependences of ionic conductivity and viscosity followed an Arrhenius equation with parameters depending only weakly on the salt concentration. The fluid behavior of the electrolytes could be reconciled with the Bingham plastic model with parameters being functions of salt concentration.
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