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Functionalization of polymer electrolytes for electrochromic windows
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Solid State Physics.
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Saving energy in buildings is of great importance because about 30 to 40 % of the energy in the world is used in buildings. An electrochromic window (ECW), which makes it possible to regulate the inflow of visible light and solar energy into buildings, is a promising technology providing a reduction in energy consumption in buildings along with indoor comfort. A polymer electrolyte is positioned at the center of multi-layer structure of an ECW and plays a significant role in the working of the ECW.

In this study, polyethyleneimine: lithium (bis(trifluoromethane)sulfonimide (PEI:LiTFSI)-based polymer electrolytes were characterized by using dielectric/impedance spectroscopy, differential scanning calorimetry, viscosity recording, optical spectroscopy, and electrochromic measurements.

In the first part of the study, PEI:LiTFSI electrolytes were characterized at various salt concentrations and temperatures. Temperature dependence of viscosity and ionic conductivity of the electrolytes followed Arrhenius behavior. The viscosity was modeled by the Bingham plastic equation. Molar conductivity, glass transition temperature, viscosity, Walden product, and iso-viscosity conductivity analysis showed effects of segmental flexibility, ion pairs, and mobility on the conductivity. A connection between ionic conductivity and ion-pair relaxation was seen by means of (i) the Barton-Nakajima-Namikawa relation, (ii) activation energies of the bulk relaxation, and ionic conduction and (iii) comparing two equivalent circuit models, containing different types of Havriliak-Negami elements, for the bulk response.

In the second part, nanocomposite PEI:LiTFSI electrolytes with SiO2, In2O3, and In2O3:Sn (ITO) were examined. Adding SiO2 to the PEI:LiTFSI enhanced the ionic conductivity by an order of magnitude without any degradation of the optical properties. The effect of segmental flexibility and free ion concentration on the conduction in the presence of SiO2 is discussed. The PEI:LiTFSI:ITO electrolytes had high haze-free luminous transmittance and strong near-infrared absorption without diminished ionic conductivity. Ionic conductivity and optical clarity did not deteriorate for the PEI:LiTFSI:In2O3 and the PEI:LiTFSI:SiO2:ITO electrolytes.

Finally, propylene carbonate (PC) and ethylene carbonate (EC) were added to PEI:LiTFSI in order to perform electrochromic measurements. ITO and SiO2 were added to the PEI:LiTFSI:PC:EC and to a proprietary electrolyte. The nanocomposite electrolytes were tested for ECWs with the configuration of the ECWs being plastic/ITO/WO3/polymer electrolyte/NiO (or IrO2)/ITO/plastic. It was seen that adding nanoparticles to polymer electrolytes can improve the coloring/bleaching dynamics of the ECWs.

From this study, we show that nanocomposite polymer electrolytes can add new functionalities as well as enhancement in ECW applications.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. , 172 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1057
Keyword [en]
Electrochromism, Polymer electrolytes, PEI, LiTFSI, Nanoparticles, Ionic conductivity, Ion-pair relaxation, Near-infrared absorption
National Category
Nano Technology Composite Science and Engineering Textile, Rubber and Polymeric Materials
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
URN: urn:nbn:se:uu:diva-204437ISBN: 978-91-554-8714-0 (print)OAI: oai:DiVA.org:uu-204437DiVA: diva2:639434
Public defence
2013-09-20, Polhemsalen, Ångström Laboratory, Lägerhyddsvägen 1, Uppsala, 13:15 (English)
Opponent
Supervisors
Available from: 2013-08-30 Created: 2013-08-05 Last updated: 2014-01-07
List of papers
1. PEI-LiTFSI electrolytes for electrochromic devices: Characterization by differential scanning calorimetry and viscosity measurements
Open this publication in new window or tab >>PEI-LiTFSI electrolytes for electrochromic devices: Characterization by differential scanning calorimetry and viscosity measurements
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2010 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 94, no 12, 2399-2404 p.Article in journal (Refereed) Published
Abstract [en]

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.

Keyword
Polymer electrolyte, Electrochromic, Smart window, PEI, DSC, Viscosity
National Category
Chemical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-135307 (URN)10.1016/j.solmat.2010.08.025 (DOI)000283959500066 ()
Available from: 2011-09-21 Created: 2010-12-06 Last updated: 2017-12-11Bibliographically approved
2. Ion conduction of branched polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide electrolytes
Open this publication in new window or tab >>Ion conduction of branched polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide electrolytes
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2011 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 57, 201-206 p.Article in journal (Refereed) Published
Abstract [en]

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.

Keyword
Ionic conductivity, Poly (ethylene imine), Arrhenius behavior, Walden rule, Ion pairing
National Category
Other Materials Engineering
Research subject
Chemistry with specialization in Polymer Chemistry; Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-163443 (URN)10.1016/j.electacta.2011.04.040 (DOI)000298463900029 ()
Available from: 2011-12-12 Created: 2011-12-12 Last updated: 2017-12-08Bibliographically approved
3. Ionic relaxation in polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide polymer electrolytes
Open this publication in new window or tab >>Ionic relaxation in polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide polymer electrolytes
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2010 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 108, no 7, 074102- p.Article in journal (Refereed) Published
Abstract [en]

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.

National Category
Physical Sciences Engineering and Technology
Identifiers
urn:nbn:se:uu:diva-133611 (URN)10.1063/1.3490133 (DOI)000283222200101 ()
Available from: 2011-09-21 Created: 2010-11-11 Last updated: 2017-12-12Bibliographically approved
4. [PEI-SiO2]:[LiTFSI] nanocomposite polymer electrolytes: Ion conduction and optical properties
Open this publication in new window or tab >>[PEI-SiO2]:[LiTFSI] nanocomposite polymer electrolytes: Ion conduction and optical properties
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2012 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 98, 465-471 p.Article in journal (Refereed) Published
Abstract [en]

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.

Keyword
Polymer electrolyte, Nanocomposite, PEI, LiTFSI, SiO2
National Category
Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-171404 (URN)10.1016/j.solmat.2011.11.021 (DOI)000300536500065 ()
Available from: 2012-03-20 Created: 2012-03-19 Last updated: 2017-12-07Bibliographically approved
5. Ion conduction mechanism of nanocomposite polymer electrolytes comprised of polyethyleneimine–lithium bis(trifluoromethylsulfonyl)imide and silica
Open this publication in new window or tab >>Ion conduction mechanism of nanocomposite polymer electrolytes comprised of polyethyleneimine–lithium bis(trifluoromethylsulfonyl)imide and silica
2014 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 119, 164-168 p.Article in journal (Refereed) Published
National Category
Nano Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-204451 (URN)10.1016/j.electacta.2013.12.032 (DOI)000335877000023 ()
Available from: 2013-08-05 Created: 2013-08-05 Last updated: 2017-12-06Bibliographically approved
6. A polymer electrolyte with high luminous transmittance and low solar throughput: Polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide with In2O3:Sn nanocrystals
Open this publication in new window or tab >>A polymer electrolyte with high luminous transmittance and low solar throughput: Polyethyleneimine-lithium bis(trifluoromethylsulfonyl) imide with In2O3:Sn nanocrystals
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2012 (English)In: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 100, no 24, 241902- p.Article in journal (Refereed) Published
Abstract [en]

Chemically prepared similar to 13-nm-diameter nanocrystals of In2O3:Sn were included in a polyethyleneiminelithium bis(trifluoromethylsulfonyl) imide electrolyte and yielded high haze-free luminous transmittance and strong near-infrared absorption without deteriorated ionic conductivity. The optical properties could be reconciled with effective medium theory, representing the In2O3:Sn as a free electron plasma with tin ions screened according to the random phase approximation corrected for electron exchange. This type of polymer electrolyte is of large interest for opto-ionic devices such as laminated electrochromic smart windows.

National Category
Physical Sciences Engineering and Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-178647 (URN)10.1063/1.4728994 (DOI)000305269200024 ()
Available from: 2012-08-02 Created: 2012-08-01 Last updated: 2017-12-07Bibliographically approved
7. Electrochromic Devices with Polymer Electrolytes Functionalized by SiO2 and In2O3:Sn Nanoparticles: Rapid Coloring/Bleaching Dynamics and Strong Near-Infrared Absorption
Open this publication in new window or tab >>Electrochromic Devices with Polymer Electrolytes Functionalized by SiO2 and In2O3:Sn Nanoparticles: Rapid Coloring/Bleaching Dynamics and Strong Near-Infrared Absorption
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2014 (English)In: Solar Energy Materials and Solar Cells, ISSN 0927-0248, E-ISSN 1879-3398, Vol. 126, 241-247 p.Article in journal (Refereed) Published
Abstract [en]

We studied the optical properties and coloring/bleaching dynamics of electrochromic devices based on tungsten oxide and nickel oxide and incorporating polymer electrolytes functionalized by adding about one percent of nanoparticles of SiO2 (fumed silica) or In2O3:Sn. SiO2 improved the coloring/bleaching dynamics and In2O3:Sn quenched the near-infrared transmittance. Both of these effects can be important in electrochromic smart windows, and our results point at the advantage of a polymer laminated construction over a monolithic one.

National Category
Nano Technology
Research subject
Engineering Science with specialization in Solid State Physics
Identifiers
urn:nbn:se:uu:diva-204448 (URN)10.1016/j.solmat.2013.06.010 (DOI)000338395100035 ()
Conference
10th International Meeting on Electrochromism (IME), Holland, MI, August 12-16, 2012
Available from: 2013-08-05 Created: 2013-08-05 Last updated: 2017-12-06Bibliographically approved

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Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf