Study of the LaNi_3.55Mn_0.4Al_0.3Co_0.75 hydrogen storage anode /KOH interface by electrochemical impedance spectroscopy (EIS) during a galvanostatic cycling

This study aimed to evaluate the electrochemical performance of a compound through electrochemical impedance spectroscopy technique. The findings presented in this work unequivocally establish the interdependency between cycling and all the investigated electrochemical parameters. Remarkably, we noted a noticeable decrease in absorption resistance during the initial cycles, as evidenced by the reduction in R-ct values from 1.3 Omega. cm(2) (uncycled electrode) to 0.9 Omega.cm(2) (3rd cycle), indicating an improvement in the activation properties of the electrode. However, the first charge/discharge cycles showed a decrease in double-layer capacity and absorption capacity. Furthermore, we observed a surge in exchange current value from 19 mA.cm(-2) to 28 mA.cm(-2) during the second cycle, followed by a gradual decline towards a range of 22.5 mA.cm(-2) at the 10th cycle. The hydrogen coefficient also underwent significant changes during cycling, increasing initially and reaching a maximum value of around 1.77 x 10(-11) cm(2).s(-1) at the 5th cycle.