TY - JOUR

T1 - Relationships between polypyrrole synthesis conditions, its morphology and electronic structure with supercapacitor properties measured in electrolytes with different ions and pH values

AU - Iurchenkova, A. A.

AU - Kallio, T.

AU - Fedorovskaya, E. O.

N1 - Funding Information: This work was supported by the Ministry of Science and Higher Education of the Russian Federation project No FSUS-2020-0036. We thank HZB (Helmholtz Zentrum Berlin) for the allocation of synchrotron radiation beam time. The TEM was performed on the equipment of CKP “VTAN” in the ATRC department of NSU by G. K. Krivyakin. The authors acknowledge S. A. Martynova for FTIR measurements and E. V. Lobiak for XPS spectra. The SEM was performed on the equipment of Aalto OtaNano Nanomicroscope Center. The Raman spectra were performed on equipment of Aalto OtaNano Low-Temperature Laboratory. Publisher Copyright: © 2021 Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021/9/20

Y1 - 2021/9/20

N2 - Despite a large number of articles about synthesis methods, structure, morphology and electrochemical properties of polypyrrole, none of these works reports the relationships between polypyrrole synthetic conditions, the electronic states of atoms in the polymer chains and its electrochemical properties in various electrolytes. Our work is dedicated to filling part of this gap. This work is focused on the effect of the synthetic medium used for polypyrrole synthesis on their atomic and electronic structure and morphology as well as investigation of the influence of these on the electrochemical characteristics of polypyrrole in aqueous electrolytes with different ions and pH values within a supercapacitor setup. It is shown that synthetic medium does not affect polymer particle shapes but changes particle sizes. Using oxygen functional groups containing synthetic medium based on water and ethanol leads to a decrease in C:N ratio, increase in C:O ratio, increase in the concentration of positively charged nitrogen-species and formation of linear-structured polymer chains. Contrary, acetonitrile-based synthetic medium without oxygen-containing functional groups leads to an increase in C:N ratio and concentration of neutrally charged nitrogen species, decrease in C:O ratio and formation of branched-structured polymer chains. Electrochemical properties of polypyrrole depend on the nature of the electrolyte, then nitrogen species and oxygen-containing functional groups in polypyrrole structure, and the size of polypyrrole particles. The favorable electrolyte for using polypyrrole in supercapacitors is neutral. The specific capacitance of polypyrrole produced in acetonitrile is shown to reach the value of ~ 385 F g −1 which is stable for more than 10,000 cycles in 1M KCl aqueous solution.

AB - Despite a large number of articles about synthesis methods, structure, morphology and electrochemical properties of polypyrrole, none of these works reports the relationships between polypyrrole synthetic conditions, the electronic states of atoms in the polymer chains and its electrochemical properties in various electrolytes. Our work is dedicated to filling part of this gap. This work is focused on the effect of the synthetic medium used for polypyrrole synthesis on their atomic and electronic structure and morphology as well as investigation of the influence of these on the electrochemical characteristics of polypyrrole in aqueous electrolytes with different ions and pH values within a supercapacitor setup. It is shown that synthetic medium does not affect polymer particle shapes but changes particle sizes. Using oxygen functional groups containing synthetic medium based on water and ethanol leads to a decrease in C:N ratio, increase in C:O ratio, increase in the concentration of positively charged nitrogen-species and formation of linear-structured polymer chains. Contrary, acetonitrile-based synthetic medium without oxygen-containing functional groups leads to an increase in C:N ratio and concentration of neutrally charged nitrogen species, decrease in C:O ratio and formation of branched-structured polymer chains. Electrochemical properties of polypyrrole depend on the nature of the electrolyte, then nitrogen species and oxygen-containing functional groups in polypyrrole structure, and the size of polypyrrole particles. The favorable electrolyte for using polypyrrole in supercapacitors is neutral. The specific capacitance of polypyrrole produced in acetonitrile is shown to reach the value of ~ 385 F g −1 which is stable for more than 10,000 cycles in 1M KCl aqueous solution.

KW - Aqueous electrolytes

KW - Electronically conducting polymer

KW - FTIR

KW - Polypyrrole

KW - Supercapacitors

KW - XPS

UR - http://www.scopus.com/inward/record.url?scp=85111035319&partnerID=8YFLogxK

U2 - 10.1016/j.electacta.2021.138892

DO - 10.1016/j.electacta.2021.138892

M3 - Article

AN - SCOPUS:85111035319

VL - 391

JO - Electrochimica Acta

JF - Electrochimica Acta

SN - 0013-4686

M1 - 138892

ER -