Study on the effect of Ce on the performance of Mg–Ni hydrogen storage alloy coatings and the mechanism of deposition process

Abstract

Mg–Ni alloys have high hydrogen storage capacity, easy activation, high discharge capacity but poor corrosion resistance. In order to further improve the hydrogen storage performance and corrosion resistance of Mg–Ni alloys, Ce metal was introduced into Mg–Ni alloys by electrodeposition. The hydrogen storage performance, corrosion resistance and electrochemical behavior of Mg–Ni–Ce hydrogen storage alloy coatings were investigated by electrochemical method. The first charging capacity of the Mg–Ni–Ce hydrogen storage alloy coatings is 797 mA h g⁻¹, and the first discharging capacity is 716.5 mA h g⁻¹. Compared with Mg–Ni alloy coatings, the addition of Ce element is beneficial to the positive shift of the corrosion voltage of the alloy and the improvement of corrosion resistance. Through cyclic voltammetry testing, the results show that the reduction mechanism of Ce³⁺ on the copper electrode is Ce³⁺ + 3e⁻ → Ce, and the reduction process is irreversible and controlled by diffusion, with a diffusion coefficient of 7.310 × 10⁻¹¹ cm² s⁻¹.