Study of the LaNi3.55Mn0.4Al0.3Co0.75 hydrogen storage anode /KOH interface by electrochemical impedance spectroscopy (EIS) during a galvanostatic cycling

Abstract

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 Rct values from 1.3 Ω.cm2 (uncycled electrode) to 0.9 Ω.cm2 (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 × 10−11 cm2.s−1 at the 5th cycle.