Effect of the discharge rate on the electrochemical properties of LaY2Ni9 hydrogen storage alloy

Yassine Ben Belgacem (1) , Chokri Khaldi (1) , Jilani Lamloumi (1) , Hisasi Takenouti (2)

1 ENSIT - Ecole Nationale Supérieure d'ingénieurs de Tunis
2 LISE - Laboratoire Interfaces et Systèmes Electrochimiques

In this study, the LaY2Ni9 hydrogen storage alloy is prepared and the effect of the discharge rate on the electrochemical properties of the active material is investigated. The decrease of the discharge rate, firstly, facilitates the activation of the alloy, and other hand, causes the decrease of the potential difference between charging and discharging that can be correlated with both the maximum discharge capacity and the cycle number of activation. After activation, the electrochemical discharge capacity undergoes a rapid decay before slowing down during a long cycling. A good stability and cycling lifetime are observed for C/10 rate. The exchange current density at initial activation cycles increases as a function of the electrochemical cycling. The smaller the discharge rate is, the faster this growth is. The Nernst potential during the initial activation cycles for all discharge rates shifts toward more positive direction. For a long cycling and except of the C/20 rate, an oscillating stabilization of both the exchange current density and Nernst potential are observed, and the C/10 rate exhibits the best behavior, in good agreement with the good maintaining of performance.

Mots clés: Nickel-metal hydride batteries; Electrochemical characterization methods; Discharge rate; Kinetic and redox parameters

Domaines: Chimie; Autre

Yassine Ben Belgacem, Chokri Khaldi, Jilani Lamloumi, Hisasi Takenouti. Effect of the discharge rate on the electrochemical properties of LaY2Ni9 hydrogen storage alloy. Journal of Alloys and Compounds, 2015, 631, pp.7-14. ⟨10.1016/j.jallcom.2015.01.074⟩. ⟨hal-01112474⟩