Recent Progress in Mg–Co–H and Mg–Fe–H Systems for Hydrogen Energy Storage Applications

Tailoring the Kinetic Behavior of Hydride Forming Materials for Hydrogen Storage

“…Upon hydrogenation and dehydrogenation, the in situ formed core-shell nanoparticles works as reversible Li + pumps, promoting the early decomposition of LiBH 4 and providing Li + for its rehydrogenation. Furthermore, the core-shell Li x TiO 2 also improve the dehydrogenation of MgH 2 , reaction (18). The addition of 1 wt.% of TiO 2 to 2LiBH 4 + MgH 2 hydride system leads to hydrogen capacities of about 10 wt.% H 2 , markedly shorter uptake (25 min) and release hydrogen times (50 min) and reduced activations energies at 400°C.…”

“…There are some exceptions such as non-stable hydride compounds at room temperature, as for example Ti(BH 4 ) 3 , Fe(BH 4 ) 2 , Ni(AlH 4 ) 2 , among others. Moreover, several binary and complex hydrides are not even reversible [15][16][17][18][19][20]. These hydrides show large gravimetric hydrogen storage capacities ranging from 4 to about 20 wt.% H 2 and also considerable volumetric hydrogen capacity from 100 to 150 kg/m 3 .…”

“…For example, taking the PCI at T 2 ( Figure 3A), a detailed description of the process during PCI characterization can be done as follows [4,21]: Table 1. [15][16][17][18][19][20].…”

“…The rate-limiting step for the hydrogenation process of the 2LiBH 4 + MgH 2 doped with TiO 2 was one-dimensional interface-controlled mechanism (JMA, n = 1), while for the pristine material it was generally a diffusion controlled process [82]. As a novel approach, Puszkiel et al interpreted the two steps dehydrogenation process by the combination of the JMA model with n = 1 for the fast MgH 2 decomposing, reaction (18), and the modified autocatalytic Prout-Tompkins model for the decomposition of LiBH 4 /formation of MgB 2 . Therefore, this autocatalytic process accelerated with the further formation of MgB 2 .…”

New Insight on the Hydrogen Absorption Evolution of the Mg–Fe–H System under Equilibrium Conditions

“…Under certain temperature and hydrogen pressure conditions, Mg 2 FeH 6 is formed from a 2Mg:Fe elemental stoichiometric mixture. This complex hydride has the highest hydrogen volumetric density (150 kg/m 3 ) among complex hydrides, relatively high hydrogen gravimetric density (5.5 wt % H 2 ), high reaction enthalpy (~90 kJ/mol H 2 ), and high volumetric (0.49 kWh/L) and gravimetric (0.55 kWh/kg) energy densities [1,2]. Owing to these characteristics, Mg 2 FeH 6 has been investigated as thermochemical energy storage medium [1,[3][4][5][6][7].…”