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|Title:||Pseudo-capacitive behavior of multi-walled carbon nanotubes decorated with nickel and manganese (hydr)oxides nanoparticles|
|Author:||Nunes, Willian G.|
Freitas, Bruno G.A.
Oliveira, Francisca E.R.
Marque, Aline M. Pascon
Maciel Filho, Rubens
Silva, Leonardo M. Da
|Abstract:||We report on the synthesis, characterization of nickel hydroxide and manganese oxide nanoparticles decorating multiwalled carbon nanotubes composite material, and electrochemical performance for energy storage processes in symmetric electrochemical capacitors. A large pseudocapacitive voltage range of 1.7 V is presented using a coin cell containing a 1.0 M Li2SO4 aqueous solution, resulting in a maximum specific capacitance of ~ 420 F g−1 verified at 1.67 A g−1 during the discharge process. The symmetric coin cell was highly stable with a very high coulombic efficiency of ~ 99% even after 70,000 cycles of charge-discharge. The high electrochemical stability of coin cell was attributed to a synergism between the nanostructured carbon support and metal (hydr)oxides nanoparticles, i.e., the transport of electrons and ions across the porous electrode structure enables with a high degree of reversibility for the solid-state redox transitions reactions, which is the main contribution to the whole electrode specific capacitance. Near-surface structural changes of the electrodes were monitored during dynamic polarization by Raman and XRD synchrotron measurements. The presence of the active Ni–O stretching mode was verified during the charge-discharge processes according to the reversible solid-state redox process. The Raman shifts were also correlated with the reversible intercalation-deintercalation processes of Li+-ions into the MnOx host material, as well as reversible adsorption of solvated ions on the surface defects of carbon nanostructures|
Óxidos de manganes
Hidróxido de níquel
|Appears in Collections:||FEEC - Artigos e Outros Documentos|
FEQ - Artigos e Outros Documentos
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