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Carbogels: carbonized conducting polyaniline/poly(vinyl alcohol) aerogels derived from cryogels for electrochemical capacitors

Abstract

Polyaniline cryogels supported with poly(vinyl alcohol) represent soft conducting macroporous materials suitable for the conversion to aerogels by freeze-drying and, subsequently, to nitrogen-containing carbogels by the carbonization in inert atmosphere at 500–600 °C. The process was followed by thermogravimetric analysis and by Raman spectroscopy on molecular level. The macroporous morphology becomes preserved after carbonization but the specific surface area increased from 12 to 680 m2g−1 after exposure to 500 °C in inert atmosphere. The original conductivity of cryogel swollen with acid solution 0.07 S cm−1 was reduced to 2×10−4 S cm−1 for aerogel and again to 10−9 S cm−1 as the carbonization progressed. Impedance spectra display Maxwell-Wagner-Sillars relaxation typical of heterogeneous composite systems with a contribution of ionic conductivity. The decrease in conductivity is in agreement with significant drop in static dielectric constant observed by broad-band dielectric spectroscopy and decrease of spin number determined by electron paramagnetic resonance spectroscopy. Switching in the capacitive response from that dominated by faradaic surface processes at lower treatment temperatures to that of a double-layer charging at elevated temperature is evidenced, while the correlation between surface spin density and specific capacitance is emphasized. The results can be used as guidance for rational design of novel active materials for electrochemical capacitors.

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Publication details

The article was received on 03 Oct 2018, accepted on 05 Dec 2018 and first published on 05 Dec 2018


Article type: Paper
DOI: 10.1039/C8TA09574D
Citation: J. Mater. Chem. A, 2018, Accepted Manuscript
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    Carbogels: carbonized conducting polyaniline/poly(vinyl alcohol) aerogels derived from cryogels for electrochemical capacitors

    P. Bober, J. Pfleger, I. A. Pasti, N. M. Gavrilov, S. K. Filippov, D. Klepac, M. Trchova, H. Hlídková and J. Stejskal, J. Mater. Chem. A, 2018, Accepted Manuscript , DOI: 10.1039/C8TA09574D

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