Effect on Electrochemical Properties of Phases in AB-Type Zr–Ti–Nb–Ni Alloys as Nickel-Metal Hydride Batteries

Abstract

AB-type ZrTiNbNi alloys are good candidates as the negative electrode for Ni-metal hydride (MH) batteries because they have high discharge capacity around 330 mAh g ¹1 at 303 K. The Zr 0.49 Ti 0.5 Nb 0.01 Ni alloy consists of two phases, the primary-phase with B33-type orthorhombic structure and the secondary-phase with B2-type cubic structure. To compare electrochemical properties of each phase with the mother alloy, we synthesized the primary-phase and secondary phase alloys with compositions of Zr 0.54 Ti 0.47 Nb 0.01 Ni 0.98 and Zr 0.47 Ti 0.52 Nb 0.01 Ni, respectively. The discharge capacity was examined at 25 mA g ¹1 and 303 K, showing that the primary-phase alloy has the highest value of 362 mAh g ¹1 than the mother alloy (335 mAh g ¹1 ) and the secondary-phase alloy (253 mAh g ¹1 ). For cycle performance, all alloys were excellent (½95%) at 100 mA g ¹1 and 303 K. For high-rate dischargeability, the secondary-phase alloy was the best, probably because the stability of hydride for the secondary-phase alloy was lower than that for the mother and the primary-phase alloy.

Dependence of Mg, Be and Al substitution on the hydrogen storage characteristics of ZrNiH 3

“…Recently, Matsuyama et al 32 reported experimentally that the enthalpy change for the hydrogenation of Ti‐substituted ZrNi alloys is lower than that of pure ZrNi. Some other studies reported the impact of single substitution with transition metals such as Ti, Cr, Fe, V, and Mn, or with double substitution with Nb and Ti 23,29,30,46 . It was worthwhile to note that, Fe and Mn atoms present the lowest doping concentration (34%) to obtain better dehydrogenation proprieties.…”

“…Some other studies reported the impact of single substitution with transition metals such as Ti, Cr, Fe, V, and Mn, or with double substitution with Nb and Ti. 23,29,30,46 It was worthwhile to note that, Fe and Mn atoms present the lowest doping concentration (34%) to obtain better dehydrogenation proprieties. In this work, instead of using transition metals, the proposed alternative approach consists on the investigation of the effect of the substitution with alkaline earth metals Mg, Be, and post-transition metal Al, on the ternary hydride ZrNiH 3 stability in order to further improve its dehydrogenation properties in terms of enthalpy of formation as well its hydrogen storage capacity.…”

“…Ni‐MH batteries have been marketed as power sources for hybrid electric vehicles (HEVs) and also widely used for stationary energy storage and portable devices 26,27 . ZrNi‐based alloys are considered to be suitable as negative electrode active materials for Ni‐MH batteries, because of their interesting long charge/discharge cycle life, environmental feasibility, and safety 23,28‐30 . However, ZrNiH 3 hydride suffers from high thermodynamic stability ( ΔH = −68.8 kJ/mol.H 2 ) and high desorption temperature ( T des = 547 K), consequently limiting its large‐scale technological applications 24,31,32 …”

“…[18][19][20][21] In addition, it has a theoretical specific capacity of around 500 mAh/g, which is higher compared to the commercial AB 5 -type rare earth-based alloys LaNi 5 (300 mAh/g) for nickel-metal hydride (Ni-MH) rechargeable batteries. [22][23][24][25] Ni-MH batteries have been marketed as power sources for hybrid electric vehicles (HEVs) and also widely used for stationary energy storage and portable devices. 26,27 ZrNi-based alloys are considered to be suitable as negative electrode active materials for Ni-MH batteries, because of their interesting long charge/discharge cycle life, environmental feasibility, and safety.…”

“…Some other studies reported the impact of single substitution with transition metals such as Ti, Cr, Fe, V, and Mn, or with double substitution with Nb and Ti. 23,29,30,46 It was worthwhile to note that, Fe and Mn atoms present the lowest doping concentration (34%) to obtain better dehydrogenation proprieties.…”