Structural, hydrogen storage, and electrochemical performance of LaMgNi4 alloy and theoretical investigation of its hydrides

• Published in: International journal of hydrogen energy 2022-01, Vol.47 (3), p.1723-1734
• Main Authors: Li, HongXin, Wan, ChuBin, Li, XiangCao, Ju, Xin
• Format: Article
• Language: English
• Subjects: Crystal structure; DFT calculations; Hydrogen storage materials; La–Mg–Ni alloys; Metal hydride batteries
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2021.10.135

Structural, hydrogen storage, and electrochemical properties of LaMgNi4 alloy were investigated in this study to determine whether it can be used as an active material of the negative electrode in nickel–metal hydride (Ni/MH) batteries. X-ray diffraction study showed that amorphization occurs at the first dehydrogenation cycle and was recovered crystallization after 873 K annealing. Maximum hydrogen storage capacity reached 1.4 wt% in the first hydrogenation under 373 K. The reannealed alloy showed improved reversible hydrogen storage capacity at ∼0.9 wt% due to more LaNi5 phase composition. Electrodes prepared from the investigated alloy showed maximum discharge capacities of ∼340 mAh/g at 10 mA/g. The LaMgNi4 alloy electrode exhibited satisfactory cycling stability remaining 47% of its initial capacity after 250 cycles. The negative cohesive energy indicated the exothermic process and stable compound structures of the LaMgNi4 alloy and its hydrides via Density functional theory calculations. [Display omitted] •Hydrogen induced amorphization and recrystallization are confirmed in LaMgNi4 alloy.•Maximum hydrogen storage capacity can reach to 1.4 wt% under 373 K.•Maximum discharge capacity of the alloy electrode reaches ∼340 mAh/g.•Charge transfer impedance and pulverization increased during cycling.•Negative cohesive energies proved stability of LaMgNi4 and its hydrides.