Investigation of the cycle stability and diffusivity of hydrogen in the MmNi3.55Mn0.4Al0.3Co0.6Fe0.15 compound

Improvement in the low-temperature performance of AB5 metal hydride alloys by Fe-addition

“…Most of the Fe-substitution in rare-earth based AB 5 metal hydride (MH) alloys are for the purpose of replacing expensive Co [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. The general drawback of this approach is the resulting sacrifice in cycle life due to an increase in the pulverization rate during cycling.…”

Electrochemical hydrogenation of CeZr 2 Cr 4 Ni 5 –based alloys

“…Electrochemical tests were performed with a VMP Bio-logic instrument in a conventional three-electrode cell. The electrolyte is 1 M KOH aqueous solution [24][25][26][27], which was deoxygenated by bubbling argon gas during every measurement. The counter electrode was formed by the Ni oxyhydroxide Ni(OH) 2 , and the reference electrode was the Hg/ HgO immersed in 1 M KOH solution and prepared with deionized water.…”

“…On the other hand, Fig. 7b demonstrates that the anodic peak current varies linearly with the square root of the potential scan rate (q 1/2 ), reflecting a semi-infinite diffusion and irreversible charge-transfer [24]. The hydrogen diffusion coefficient in this metal hydride electrode can be estimated from the slope of the curve I ap = f (# 1/2 ) by Eq.…”

“…6 at different scan rates for the compound ball-milled during 5 h. These curves were recorded after 100 activating cycles. The cathodic scan shows an onset of the hydrogen evolution reaction at about À0.95 V followed by a continuous decrease in the cathodic current until À1.1 V. When the potential is reversed to the opposite direction, the current increases and an anodic peak was observed at about À0.85 V. This peak corresponds to the oxidation of the hydrogen atoms trapped in the interstitial sites [24]. When the scan rate increases, the anodic current increases and the peak potential slightly shifts to the positive values.…”

“…where M is the molar mass of the CeZr 2 Cr 4 Ni 5 compound, m is the effective mass of material, V M is the molecular volume of material and Q is the charge of anodic oxidation of hydrogen generated during the anodic voltammetric sweep [24].…”