Phase structure and electrochemical properties of Ml1−x Mg x Ni2.78Co0.50Mn0.11Al0.11 hydrogen storage alloys

Abstract

The effect of magnesium content on the phase structure and electrochemical properties of Ml 1)x Mg x Ni 2.78-Co 0.50 Mn 0.11 Al 0.11 (x = 0.05, 0.10, 0.20, 0.30) hydrogen storage alloys was investigated. The results of X-ray diffraction reveal that all the alloys consist of the major phase (La, Mg)Ni 3 and the secondary phase LaNi 5 . With increase in x, the relative content of the (La, Mg)Ni 3 phase increases gradually, and the maximum capacity and low temperature dischargeability of the alloy electrodes first increase and then decrease. When x is 0.20, the discharge capacity of the alloy electrode reaches 363 mAh g )1 at 293 K and 216 mAh g )1 at 233 K, respectively. The high rate dischargeability of the alloy electrodes increases with increase in x. When the discharge current density is 1200 mA g )1 , the high rate dischargeability of the alloy electrodes increases from 22.0% to 50.4% with x increasing from 0.05 to 0.30. The cycling stability of the electrodes decreases gradually with increase in magnesium content.

Effect of metal oxides on electrochemical performances of La–Mg–Ni-based alloys

“…So it is urgent to develop new types of alloys with higher capacity and other electrochemical properties. Some recent research showed that La-Mg-Ni-based AB 3 -type alloys were promising negative electrode materials for their comparatively higher discharge capacity; however, this type of alloys should be improved in their overall electrochemical properties, especially the cycling stability for practical application [4][5][6][7].…”