Electrochemical Characterization of Nickel Hydroxide Electrodes with MWCNT

MARIELA GISELA ORTIZ; SILVIA GRACIELA REAL; ELIDA BEATRIZ CASTRO

Querétaro

Encuentro; 64th Annual Meeting of the International Society of Electrochemistry; 2013

International Society of Electrochemistry

Alkaline secondary batteries are widely required in the current market of electronic devices. Particularly, Ni/H2 and Ni/MH batteries have, as active material, nickel hydroxide in the positive electrode. The nickel hydroxide behaves as a semiconductor material so, it becomes necessary to overcome this limitation. Studies have been conducted using various additives (C, Ca, Ba, Zn, Cd, Al, Co). The carbon nanotubes (NTC) employed as additive in nickel hydroxide electrodes was first studied by Lv et al. who found that the addition of NTC may improve battery performance at high download speeds [1]. However, is still pending to improve electrical contact between the active material and the additive. A poor electrical contact yields ohmic overpotential and consequently capacity loss at high currents. In this work, we study the addition of multiwall carbon nanotubes (MWCNT). The active material was prepared by hydrothermal synthesis method. For the synthesis, the MWCNT was incorporated along with the NiSO4 and NaOH. Two materials were synthesized according to different reaction times (4 and 24 hr.). The characterization was performed by optical (SEM, TEM, XRD) and electrochemical techniques (charge-discharge cycles, cyclic voltammetry, electrochemical impedance spectroscopy-EIS-). The EIS technique and a physicochemical model developed in the laboratory are powerful tools for physicochemical and structural parameter estimation such as: electrical conductivity, diffusion coefficient of H+, specific area, etc. [2]. This knowledge allows electrochemical performance optimization of the studied systems.