Galvanostatic and EIS studies of the LaNi3.55Mn0.4Al0.3Co0.75 metal hydride anode during cycling

The electrochemical properties of LaNi
3.55
Mn
0.4
Al
0.3
Co
0.75
alloy used as an anode in nickel-metal hydride batteries were investigated at ambient temperatures. Several techniques, such as the galvanostatic charging and discharging and electrochemical impedance spectroscopy (EIS) were applied to characterize these electrochemical properties. The discharge capacity of the LaNi
3.55
Mn
0.4
Al
0.3
Co
0.75
alloy increases to reach 337 mAh g
⁻¹
after 6 cycles and decreases to 300 mAh g
⁻¹
after 25 cycles then stabilizes around this same value indicating good cycling held.The EIS study shows a clear dependence on cycling especially for the semicircle in the low frequency region. The contribution of this semicircle decreases considerably during cycling: from 117 Ω cm
²
for the raw material to 7Ω cm
²
after 23 cycles. This reflects a significant change in the extracted values from this region.