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- Bandara, T M W J, 1968, et al.
(författare)
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Effect of thermal history and characterization of plasticized, composite polymer electrolyte based on PEO and tetrapropylammonium iodide salt (Pr4N+I-).
- 2009
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Ingår i: Solid State Ionics. - : Elsevier BV. - 0167-2738. ; 180:4-5, s. 362-
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Tidskriftsartikel (refereegranskat)abstract
- The search for anionic conductors based on solid polymer electrolytes is important for the development of photo-electrochemical (PEC) solar cells due to their many favourable chemical and physical properties. Although solid polymer electrolytes have been extensively studied as cation, mainly lithium ion, conductors for applications in secondary batteries, their use as anionic conductors have not been studied in greater detail. In a previous paper we reported the application of a PEO based iodide ion conducting electrolyte in a PEC solar cell. This electrolyte had the composition PEO: Pr4N+I- = 9:1 with 50 wt.% ethylene carbonate (EC). In this work we have studied the effect of incorporating alumina filler on the properties of this electrolyte. The investigation was extended to electrical and dielectric measurements including high frequency impedance spectroscopy and thermal analysis.In the DSC themograms two endothermic peaks have been observed on heating, one of these peaks is attributed with the melting of the PEO crystallites, while the other peak with a melting temperature similar to 30 degrees C is attributed to the melting of the EC rich phase. The melting temperature of both these peaks shows a marked variation with alumina content in the electrolyte. The temperature dependence of the conductivity shows that there is an abrupt conductivity increase in the first heating run evidently due to the melting of the EC rich phase. High conductivity values are retained at lower temperatures in the second heating. Conductivity isotherms show the existence of two maxima, one at -5% Al2O3 content and the other at similar to 15%. The occurrence of these two maxima has been explained in terms of the interactions caused by alumina grains, the crystallinity and melting of the PEO rich phase. As seen from latent heat of melting, the crystallinity of the electrolyte has reduced considerably during the first heating run. In contrast to the conductivity enhancement caused by ceramic fillers in PEO-based cation containing electrolytes, no conductivity enhancement has been observed in the present PEO based anionic conducting materials by adding alumina except at low temperatures. (C) 2009 Elsevier B.V. All rights reserved.
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| 2. |
- Bandara, T M W J, 1968, et al.
(författare)
-
Thermal and dielectric properties of PEO/EC/Pr4N+I- polymer electrolytes for possible applications in photo-electro chemical solar cells.
- 2009
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Ingår i: Journal of Solid State Electrochemistry. - : Springer Science and Business Media LLC. - 1432-8488 .- 1433-0768. ; 13:8
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Tidskriftsartikel (refereegranskat)abstract
- The anion-conducting polymer electrolyte polyethylene oxide (PEO)/ethylene carbonate (EC)/Pr4N+I-/I-2 is a candidate material for fabricating photo-electrochemical (PEC) solar cells. Relatively high ionic conductivity values are obtained for the plasticized electrolytes; at room temperature, the conductivity increases from 7.6 x 10(-9) to 9.5 x 10(-5) S cm(-1) when the amount of EC plasticizer increases from 0% to 50% by weight. An abrupt conductivity enhancement occurs at the melting of the polymer; above the melting temperature, the conductivity can reach values of the order of 10(-3) S cm(-1). The melting temperature decreases from 66.1 to 45.1 A degrees C when the EC mass fraction is increased from 0% to 50%, and there is a corresponding reduction in the glass transition temperature from -57.6 to -70.9 A degrees C with the incorporation of the plasticizer. The static dielectric constant values, epsilon(s), increase with the mass fraction of plasticizer, from 3.3 for the unplasticized sample to 17.5 for the 50% EC sample. The dielectric results show only small traces of ion-pair relaxations, indicating that the amount of ion association is low. Thus, the iodide ion is well dissociated, and despite its large size and relatively low concentration in these samples, the iodide ion to ether oxygen ratio is 1:68, a relatively efficient charge carrier. A further enhancement of the ionic conductivity, especially at lower temperatures, is however desired for these applications.
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