Facultad Regional La Plata

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Subject: search.filters.subject.Electrochemical characterization

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    Electrochemical characterization of nickel hydroxide nanomaterials as electrodes for NiMH batteries
    (Springer, 2016-08-23) Real, Silvia; Ortiz, Mariela; Castro, Élida Beatriz
    β-Nickel hydroxide was successfully synthesized by a hydrothermal method. Nano-nickel hydroxide material was characterized by X-ray diffraction, infrared absorption spectroscopy, and transmission electron microscopy. They were employed as additives to the positive electrode of Ni-MH batteries. Working electrodes, with mixtures of commercial nickel hydroxide and nano-nickel hydroxide (0–10 wt.%) as active material, were prepared. Cyclic voltammetry, charge discharge profiles, and electrochemical impedance spectroscopy studies were carried out to evaluate the electrochemical performance of the nickel electrode, in 7 M KOH electrolyte, at 25 °C. The presence of nano-nickel hydroxide improves the electrochemical behavior of the active material. The electrochemical impedance spectroscopy (EIS) results were analyzed employing a modified version of previously developed physicochemical model that takes into account the main structural and physicochemical parameters that control these systems.
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    Electrochemical characterization of Nickel Hydroxide electrodes with MWCNT
    (Anual Meeting of ISE, 2013-09-08) Ortiz, Mariela; Real, Silvia; Castro, Élida Beatriz
    Alkaline secondary batteries are widely required in the current market of electronic devices. Particularly, nickel hydroxide active material is the positive electrode in Ni/H2 and Ni/MH batteries. Due to their semiconductor nature, it becomes necessary to solve this limitation. A poor electrical contact yields ohmic overpotential and capacity loss at high currents. The carbon nanotubes (CNT) employed as additive was first studied by Lvetal. Who found that the addition of NTC may improve battery performance at high download speeds. However, discussions about the way that CNT affect structural and kinetic parameters are still acking. In this work, the addition of multiwall carbon nanotubes (MWCNT) is investigated. The active material was prepared by hydrothermal synthesis method. The characterization was performed by optical (SEM, TEM, XRD) and electrochemical techniques (charge‐discharge cycles, cyclic voltammetry, electrochemical impedance spectroscopy ‐ EIS). The EIS technique along with a physicochemical model developed in the laboratory, are powerful tools for the estimation of physicochemical and structural parameter such as: specific active area, effective conductivity and diffusion coefficient of H+[2]. This knowledge allows electrochemical performance optimization of the systems.