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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.)

Niobium pentoxide nanoparticles @ multi-walled carbon nanotubes and activated carbon composite material as electrodes for electrochemical capacitors

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Vicentini, Rafael [1] ; Nunes, Willian [1] ; Freitas, Bruno G. A. [1] ; Da Silva, Leonardo M. [2] ; Soares, Davi Marcelo [1] ; Cesar, Reinaldo [1] ; Rodella, Cristiane B. [3] ; Zanin, Hudson [1]
Total Authors: 8
[1] Univ Estadual Campinas, Sch Elect & Comp Engn, Carbon Sci Tech Labs, Ctr Innovat New Energies, Adv Energy Storage Div, Av Albert Einstein 400, BR-13083852 Campinas, SP - Brazil
[2] Fed Univ Jequitinhonha & Mucuris Valley, Dept Chem, Rodovia MGT 367, Km 583, 5000, Alto Jacuba, 39, BR-100000 Diamantina, MG - Brazil
[3] Brazilian Ctr Res Energy & Mat CNPEM, Brazilian Synchrotron Light Lab LNLS, BR-13083970 Campinas, SP - Brazil
Total Affiliations: 3
Document type: Journal article
Source: ENERGY STORAGE MATERIALS; v. 22, p. 311-322, NOV 2019.
Web of Science Citations: 0

We report here on a novel method to produce nanostructured porous carbon composite electrodes decorated with niobium pentoxide nanoparticles. The carbon support is composed of multiwalled carbon nanotubes and activated carbon composite material. Nanotubes work simultaneously as binder and additive for activated carbon supported on the nickel-aluminide current collector. The hydrated niobium pentoxide nanoparticles attached on the carbon surface improved the charge storage process, introducing Faradaic reactions (pseudocapacitance) to the storage mechanism. The pseudocapacitive process involving the niobium pentoxide was stable since the oxide nanoparticles partially covered with a porous carbon layer were not deactivated. This approach improved the electrical conductivity and chemical stability and also avoided reaggregation and deactivation of niobium pentoxide nanoparticles by passivation. The electrochemical performance of the symmetric coin cell using an aqueous lithium sulfate solution was evaluated by cyclic voltammetry, galvanostatic (re)charge/discharge curves, and the electrochemical impedance spectroscopy techniques. In short, our results showed that the composite material has good electrochemical properties, including high specific capacitance (similar to 220 F g(-1)), long lifespan (more than 200 thousand cycles), and high energy (0.11-6.5 kW kg(-1)) and power (3.1-6.1 Wh kg(-1)) densities for the applied gravimetric currents in the range of 0.5-30 A g(-1). We additionally performed in situ Raman analyses (operando studies) using the composite electrode under dynamic potential conditions. We observed reversible shift on the D band position, and the intensity of the Raman signal decreased during cycling due to SO42- adsorption. (AU)

FAPESP's process: 17/11958-1 - Advanced energy storage division
Grantee:Rubens Maciel Filho
Support type: Research Grants - Research Centers in Engineering Program
FAPESP's process: 14/02163-7 - Development of supercapacitors devices from graphene, carbon nanotubes and diamonds
Grantee:Hudson Giovani Zanin
Support type: Research Grants - Young Investigators Grants