Nickel oxide nanoparticles supported onto oriented multi-walled carbon nanotube as electrodes for electrochemical capacitors

Autor(es)

Nunes, Willian G. ^[1] ; Da Silva, Leonardo M. ^[2] ; Vicentini, Rafael ^[1] ; Freitas, Bruno G. A. ^[1] ; Costa, Lenon H. ^[1] ; Pascon, Aline M. ^[1] ; Zanin, Hudson ^[1]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, Sch Elect & Comp Engn, Adv Energy Storage Div, Ctr Innovat New Energies, Carbon Sci Tech Labs, Av Albert Einstein 400, BR-13083852 Campinas, SP - Brazil

^[2] Fed Univ Jequitinhonha & Mucuris Valley, Dept Chem, Highway MGT 367, Km 583, BR-39100000 Diamantina, MG - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Electrochimica Acta; v. 298, p. 468-483, MAR 1 2019.
• Citações Web of Science: 3

Resumo

We report an electrode material for supercapacitors composed of nickel oxide (NiO) nanoparticles supported onto radially oriented multi-walled carbon nanotubes (CNTs) using a stainless-steel fine-mesh as the support (AISI: CNT-NiO). CNT scaffolds showed a turbostratic multi-walled structure with an interplanar spacing of 0.32 +/- 0.02 nm and a diameter of similar to 20-100 nm. NiO nanoparticles exhibited a diameter of similar to 2-7 nm. X-ray data confirmed the presence of NiO in the scaffold. A large pseudocapacitive voltage range of 2.0 V was obtained in a 1.0 M Li2SO4 aqueous solution. The main contribution to the overall pseudocapacitance is due to the presence of reversible solid-state surface Faradaic reactions involving the Ni(II)/Ni(III) redox couple. High specific capacitance values of similar to 1200 F g(-1) at 5 A g(-1) for the AISI: CNT-NiO electrode were extracted from galvanostatic discharge curves. Considering the contribution of negative voltages, the specific power and energy determined using cyclic voltammetry exhibited values of similar to 140 Wh kg(-1) and similar to 9 W kg(-1), respectively, at 0.02 V s(-1). A specific capacitance of similar to 1028 F g(-1) was obtained at this scan rate. Even after 40,000 cycles carried out under galvanostatic conditions, the symmetric coin cell remained stable with a very high coulombic efficiency of similar to 99%, which is a remarkable result. Also, we attributed to carbon nanotubes an extraordinary stability as electron drain on the current collector. The morphology factor analysis revealed that 19% of the electrochemically active surface area is confined to the inner surface regions of the porous nanostructured active layer. A low value of 0.15 m Omega g was extracted for the equivalent series resistance. New insights are presented concerning the true meaning of negative voltages for coin cells. Interesting findings regarding the porous nature of electrodes were elucidated using the impedance technique. (C) 2018 Published by Elsevier Ltd. (AU)

• Processo FAPESP: 17/19222-4 - Desenvolvimento de dispositivo armazenador e fornecedor de energia elétrica e metodologia de análise dinâmica em modo de operação
• Beneficiário: Lenon Henrique da Costa
• Modalidade de apoio: Bolsas no Brasil - Doutorado Direto
• Processo FAPESP: 14/02163-7 - Desenvolvimento de dispositivos supercapacitores a partir de grafenos, nanotubos de carbono e diamantes
• Beneficiário: Hudson Giovani Zanin
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores
• Processo FAPESP: 16/25082-8 - Desenvolvimento de protótipo armazenador e fornecedor de energia
• Beneficiário: Lenon Henrique da Costa
• Modalidade de apoio: Bolsas no Brasil - Mestrado