Effect of stoichiometric ratio on discharge efficiency of hydrogen storage alloy electrodes

Hydrogen diffusion behavior in α-solid solution phase of LmNi3.55Co0.75Mn0.4Al0.3 metal hydride electrode—Effect of temperature

“…The apparent energy of activation for hydrogen diffusion was calculated to be 27.9 kJ mol −1 . This is consistent with the results of 26.9 kJ mol −1 obtained by Iwakura et al [28] for the hydrogen diffusion in MmNi 3.6 Mn 0.4 Al 0.3 Co 0.7 .…”

“…The obtained results were found to be consistent with the reported values for alloy electrodes with the same or similar composition at low concentration of hydrogen initially charged [9,14,[16][17][18]21,24,25]. Conversely, some reports suggest that the values of hydrogen diffusion coefficient are one or maybe two orders of magnitude lower or higher [8,10,11,13,15,[26][27][28]. This great discrepancy in the reported values of hydrogen diffusion coefficient in the alloy electrodes, even with the same composition, might be attributed to the following.…”

Effect of La on the crystalline and electrochemical properties of Ti-Zr-Ni melt-spun alloys

“…As mentioned above, the amorphous phase around the I-phase led to an easier access of hydrogen to the I-phase due to avoiding the long-range diffusion through an already formed hydride. It was well known that the HRD of the metal-hydride electrodes was dominated by the electrochemical kinetics of the charge-transfer reaction at the electrode/electrolyte interface and the hydrogen diffusion rate within the bulky alloy electrode, which were reflected in the value of R ct and/or I 0 , being a measure of the catalytic activity of an alloy electrode, as well as in the D, which characterized the mass transport properties of an alloy electrode [21][22]. The I 0 and D of the Ti 45 Zr 30 Ni 25 La alloy electrode were higher than those of the Ti 45 Zr 30 Ni 25 alloy electrode, which was beneficial to dischargeability and resulted in a higher HRD.…”

Improvement in cyclic stability of rare-earth-based hydrogen storage alloys prepared by twin-roller rapid quenching process

“…It has been reported that several electrochemical properties of nonstoichiometric rare-earth-based alloys are better than those of stoichiometric ones [7][8][9]. For example, the second phase in hyper-stoichiometric alloys has a relatively high electrocatalytic activity that apparently increase the cyclic stability of the alloys.…”