Development of mischmetal-nickel and titanium-cobalt hydrides for hydrogen storage

Hydriding combustion synthesis of TiFe

“…Ti + H 2 = TiH 2 + 144 kJ (1) The adiabatic flame temperature, T ad , of the reaction is estimated to be as high as 1800 • C. Even if equimolar Fe were added to Ti, the T ad is estimated to be as high as 1600 • C, which is higher than the eutectic temperature of the Ti-Fe system. A previous study showed that the HCS is accomplished when the raw materials are heated to the eutectic temperature of the system [8]; therefore, it seems to be possible to synthesize TiFe, whose eutectic temperature is 1085 • C, by HCS utilizing the large reaction heat of TiH 2 formation.…”

“…Difficulties with activation make TiFe to remain unpractical in spite of the practical features. Osumi et al quantified the problem evaluating various metal hydrides in terms of their hydrogen storage properties including activation ease, hydrogen capacity, cycling property, heat of formation, temperature and pressure required for hydriding reaction, production cost and safety [1,2]. In the evaluation, TiFe scored 25 points as much as the points of LaNi 5 , which has been used * Corresponding author.…”

Effect of rare earth on lattice size and equilibrium hydrogen pressure for AB5-type MmNi3.55Co0.75Al0.30Mn0.40

“…In general, Mm is composed of light rare earths such as Ce, La, Nd and Pr. So far, hydrogenation property of MmNi 5 or its related alloys MmNi 5−x M x (M: typical or transition element) have been investigated with great interest and in much detail [1][2][3][4].…”

The role of Mn in C14 Laves phase multi-component alloys for NiMH battery application

“…Most early studies of Mn substitution were performed using LaNi 5 binary alloys [1][2][3][4][5][6], while later commercial applications in nickel metal hydride (NiMH) batteries were based on Mn substitution for Ni in Mm-based AB5 system [7][8][9][10][11][12][13][14][15][16][17]. In this AB5 system, the addition of Mn has been shown to increase lattice parameters [2,11,17], cell volume [12], absolute value of heat of formation [9,12], cycle life [4], high rate dischargeability (HRD) [15,16] while at the same time decreasing plateau pressure [2,5,9,17], isotherm slope factor [17], absorption/desorption hysteresis [14], volume expansion during hydriding [4], and yet had no effect on alloy capacity [15].…”