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Wang, Hui
Publications (6 of 6) Show all publications
Zhao, D., Wang, H., Ullah Khan, Z., Chen, J. C., Gabrielsson, R., Jonsson, M., . . . Crispin, X. (2016). Ionic thermoelectric supercapacitors. Energy & Environmental Science, 9(4), 1450-1457
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2016 (English)In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 9, no 4, p. 1450-1457Article in journal (Refereed) Published
Abstract [en]

Temperature gradients are generated by the sun and a vast array of technologies and can induce molecular concentration gradients in solutions via thermodiffusion (Soret effect). For ions, this leads to a thermovoltage that is determined by the thermal gradient Delta T across the electrolyte, together with the ionic Seebeck coefficient alpha(i). So far, redox-free electrolytes have been poorly explored in thermoelectric applications due to a lack of strategies to harvest the energy from the Soret effect. Here, we report the conversion of heat into stored charge via a remarkably strong ionic Soret effect in a polymeric electrolyte (Seebeck coefficients as high as alpha(i) = 10 mV K-1). The ionic thermoelectric supercapacitor (ITESC) is charged under a temperature gradient. After the temperature gradient is removed, the stored electrical energy can be delivered to an external circuit. This new means to harvest energy is particularly suitable for intermittent heat sources like the sun. We show that the stored electrical energy of the ITESC is proportional to (Delta T alpha(i))(2). The resulting ITESC can convert and store several thousand times more energy compared with a traditional thermoelectric generator connected in series with a supercapacitor.

Place, publisher, year, edition, pages
ROYAL SOC CHEMISTRY, 2016
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-128769 (URN)10.1039/c6ee00121a (DOI)000374351200029 ()
Note

Funding Agencies|European Research Council (ERC) [307596]; Swedish foundation for strategic research (SSF); Knut and Alice Wallenberg foundation (KAW); Swedish Energy Agency; Wenner-Gren Foundations; Advanced Functional Materials Centre at Linkoping University.

The previous status of this article was Manuscript.

Available from: 2016-05-30 Created: 2016-05-30 Last updated: 2018-08-31Bibliographically approved
Wang, H., Ail, U., Gabrielsson, R., Berggren, M. & Crispin, X. (2015). Ionic Seebeck Effect in Conducting Polymers. ADVANCED ENERGY MATERIALS, 5(11), Article ID 1500044.
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2015 (English)In: ADVANCED ENERGY MATERIALS, ISSN 1614-6832, Vol. 5, no 11, article id 1500044Article in journal (Refereed) Published
Abstract [en]

Conducting polymers display an ionic thermoelectric effect in addition to the known electronic thermoelectric effect. Their Seebeck coefficient is as large as ≈200 μV K−1. This finding discloses a new possible approach to improve the thermoelectric properties of conducting polymers by combining various types of charge carriers of the same sign.

Place, publisher, year, edition, pages
Wiley-VCH Verlag, 2015
Keywords
conducting polymers; ionic Seebeck effect; thermoelectric materials
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-119790 (URN)10.1002/aenm.201500044 (DOI)000355753300005 ()
Note

Funding Agencies|European Research Council (ERC-Starting-Grant) [307596]; Swedish foundation for strategic research; Knut and Alice Wallenberg foundation; Swedish Energy Agency; Advanced Functional Materials Center at Linkoping University

Available from: 2015-06-26 Created: 2015-06-26 Last updated: 2018-08-20
Wang, H., Khan, Z. U., Zhao, D., Berggren, M. & Crispin, X. (2015). Ionic Thermoelectric effect in Polyelectrolytes.
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2015 (English)Manuscript (preprint) (Other academic)
National Category
Physical Sciences Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-121980 (URN)
Available from: 2015-10-14 Created: 2015-10-14 Last updated: 2017-02-03Bibliographically approved
Bubnova, O., Khan, Z. U., Wang, H., Braun, S., Evans, D. R., Fabretto, M., . . . Crispin, X. (2014). Corrigendum: Semi-metallic polymers. Nature Materials, 13, 662-662
Open this publication in new window or tab >>Corrigendum: Semi-metallic polymers
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2014 (English)In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 13, p. 662-662Article in journal (Refereed) Published
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-113955 (URN)10.1038/nmat3981 (DOI)
Available from: 2015-02-04 Created: 2015-02-04 Last updated: 2018-08-20
Bubnova, O., Ullah Khan, Z., Wang, H., Braun, S., Evans, D. R., Fabretto, M., . . . Crispin, X. (2014). Semi-metallic polymers. Nature Materials, 13(2), 190-194
Open this publication in new window or tab >>Semi-metallic polymers
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2014 (English)In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 13, no 2, p. 190-194Article in journal (Refereed) Published
Abstract [en]

Polymers are lightweight, flexible, solution-processable materials that are promising for low-cost printed electronics as well as for mass-produced and large-area applications. Previous studies demonstrated that they can possess insulating, semiconducting or metallic properties; here we report that polymers can also be semi-metallic. Semi-metals, exemplified by bismuth, graphite and telluride alloys, have no energy bandgap and a very low density of states at the Fermi level. Furthermore, they typically have a higher Seebeck coefficient and lower thermal conductivities compared with metals, thus being suitable for thermoelectric applications. We measure the thermoelectric properties of various poly( 3,4-ethylenedioxythiophene) samples, and observe a marked increase in the Seebeck coefficient when the electrical conductivity is enhanced through molecular organization. This initiates the transition from a Fermi glass to a semi-metal. The high Seebeck value, the metallic conductivity at room temperature and the absence of unpaired electron spins makes polymer semi-metals attractive for thermoelectrics and spintronics.

Place, publisher, year, edition, pages
Nature Publishing Group, 2014
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-104644 (URN)10.1038/nmat3824 (DOI)000330182700027 ()
Available from: 2014-02-20 Created: 2014-02-20 Last updated: 2018-09-07
Bubnova, O., Ullah Khan, Z., Wang, H., Dagnelund, D., Arlin, J.-B., Geerts, Y., . . . Crispin, X.Advantageous thermoelectric properties of a semimetallic polymer.
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Thermoelectric generation potentially holds a solution for waste heat recovery issues provided that the availability of inexpensive, biodegradable and highly efficient thermoelectric materials is insured in the near future. Plastic thermoelectrics could successfully comply with the said requirements if the thermoelectric efficiency (ZT) of conducting polymers was higher. However, given the novelty of the subject, at present there are no clear guidelines for ZT optimization in this class of materials. The most important piece of information that is currently missing is the description of a specific electronic makeup that conducting polymers must possess in order to enable good thermoelectric performance. In the present study the thermoelectric properties of poly(3,4-ethylenedioxythiophene) derivatives with two types of counterions, i.e. poly(styrenesulfonate) (PSS) and tosylate (Tos) are evaluated. A striking variation in their thermoelectric performance is attributed to structural and morphological differences between two polymers that manifest itself in dissimilar charge transport mechanism. The superior properties of PEDOT-Tos presumably originate from a high degree of crystallinity and structural order that predetermines the tendency for bipolaron band formation. Unlike polaronic PEDOT-PSS with slowly varying density of localized states (DOS) near the Fermi level (EF), the DOS in PEDOT-Tos is characterized by higher asymmetry and higher charge carrier density at EF (similar to semimetals), which allows for higher thermopower and electrical conductivity. Therefore, we conclude that the polymers with semimetallic electronic makeup are expected to exhibit promising thermoelectric properties with bigger variation in thermopower upon doping.

Keywords
Thermoelectric, semimetal, conducting polymer, bipolaron
National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-87454 (URN)
Available from: 2014-05-31 Created: 2013-01-18 Last updated: 2017-02-03Bibliographically approved
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