“The Discharge Proceses of Porous Nickel Hydroxide Electrode: An Electrochemical Impedance Spectroscopy Study.”

S.G. REAL E.B. CASTRO D. BECKER D. BARSELLINI G. GARAVENTTA AND A. VISINTIN

Mexico

Congreso; 2006 Joint International Meeting, 210th Meeting of The Electrochemical Society, XXI Congreso de la Sociedad Mexicana de Electroquímica,; 2006

The nickel hydroxide electrode is widely used as an active material in nickel electrodes. The high power density, very good cyclability and high specific energy of these electrodes make them very competitive for extended range of applications such as electrode material for Nickel /Hydrogen and Nickel /metal hydride batteries.  The electrochemical energy storage in the nickel hydroxide electrodes is related to the reversible characteristics of the redox couple nickel hydroxide/oxihydroxide. The process reversibility is an important property of electrode materials for batteries. The nickel electrode has being study for many researchers, however there are still many factors not well understood, as the “sudden death” of the batteries, that are dependent on many factors:  the concentration of the alkaline solution, the preparation method and the global kinetics of the process.  In the case of nickel hydroxide electrode the insertion of hydrogen takes place during discharge, while the inverse process occurs during charge. In this study two types of nickel hydroxide electrodes were prepared on sintered plates, the sintered nickel electrode employs a perforated metal sheet. Into this matrix, nickel hydroxide was electrodeposited using 1,8 M Ni(NO3 )2+ y M X(NO3) solution, X being Na, Co and  Cd. The experiments were curried out using electrochemical charge-discharge cycling and electrochemical impedance spectroscopy (EIS). The results obtained by EIS for different state of discharge of nickel electrode are presented and discussed according to physicochemical models developed at the laboratory