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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Raman probing carbon & aqueous electrolytes interfaces and molecular dynamics simulations towards understanding electrochemical properties under polarization conditions in supercapacitors

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Vicentini, Rafael [1] ; Da Silva, Leonardo M. [2] ; Franco, Debora V. [2] ; Nunes, Willian G. [1] ; Fiates, Juliane [3] ; Doubek, Gustavo [3] ; Franco, Luis F. M. [3] ; Freitas, Renato G. [4] ; Fantini, Cristiano [5] ; Zanin, Hudson [1]
Total Authors: 10
[1] Univ Estadual Campinas, Adv Energy Storage Div, Carbon Sci Tech Labs, Av Albert Einstein 400, BR-13083852 Campinas, SP - Brazil
[2] Fed Univ Jequitinhonha & Mucuris Valley, Dept Chem, Rodovia MGT 367, Km 583, BR-39 10000 Diamantina, MG - Brazil
[3] Univ Campinas UNICAMP, Lab Adv Batteries, Adv Energy Storage Div, Ctr Innovat New Energies, Sch Chem Engn, BR-13083852 Campinas, SP - Brazil
[4] Univ Fed Mato Grosso, Dept Chem, ICET UFMT, BR-78060900 Cuiaba, MT - Brazil
[5] Univ Fed Minas Gerais, Dept Fis, ICEx, BR-31270901 Belo Horizonte, MG - Brazil
Total Affiliations: 5
Document type: Journal article
Source: JOURNAL OF ENERGY CHEMISTRY; v. 60, p. 279-292, SEP 2021.
Web of Science Citations: 7

Raman probing of carbon electrode and electrolyte under dynamic conditions is performed here using different aqueous electrolytes to elucidate the fundamental events occurring in electrochemical supercapacitor during charge-discharge processes. The areal capacitance ranges from 1.54 to 2.31 mF cm(-2) and it is determined using different techniques. These findings indicate that the Helmholtz capacitance governs the overall charge-storage process instead of the space charge (quantum) capacitance commonly verified for HOPG electrodes in the range of similar to 3 to 7 mu F cm(-2). Molecular dynamics simulations are employed to elucidate the origin of the reversible Raman spectral changes during the charge-discharge processes. A correlation is verified between the reversible Raman shift and the surface excesses of the different ionic species. A theoretical framework is presented to relate the effect of the applied potential on the Raman shift and its correlation with the surface ionic charge. It is proposed that the Raman shift is governed by the interaction of solvated cations with graphite promoted by polarization conditions. It is the first time that a comparative study on different aqueous electrolyte pH and cation ion size has been performed tracking the Raman spectra change under dynamic polarization conditions and contrasting with comprehensive electrochemistry and dynamic molecular simulations studies. This study shines lights onto the charge-storage mechanism with evidence of Kohn anomaly reduction in the carbon electrode during the reversible adsorption/desorption and insertion/extraction of ionic species. (C) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved. (AU)

FAPESP's process: 17/11958-1 - CINE - Advanced Energy Storage Division
Grantee:Rubens Maciel Filho
Support Opportunities: Research Grants - Research Centers in Engineering Program
FAPESP's process: 18/02713-8 - Molecular dynamics of confined fluids: equilibrium and transport properties
Grantee:Luís Fernando Mercier Franco
Support Opportunities: Research Grants - Young Investigators Grants
FAPESP's process: 16/25082-8 - Development of prototype of energy storer and supplier
Grantee:Lenon Henrique da Costa
Support Opportunities: Scholarships in Brazil - Master
FAPESP's process: 14/02163-7 - Development of supercapacitors devices from graphene, carbon nanotubes and diamonds
Grantee:Hudson Giovani Zanin
Support Opportunities: Research Grants - Young Investigators Grants
FAPESP's process: 18/20756-6 - Pseudocapacitors from metal oxides and activated carbon composites
Grantee:Willian Gonçalves Nunes
Support Opportunities: Scholarships in Brazil - Doctorate