The improved Hydrogen Storage Performances of the Multi-Component Composite: 2Mg(NH2)2–3LiH–LiBH4

Abstract

2Mg(NH2)2-3LiH-LiBH4 composite exhibits an improved kinetic and thermodynamic properties in hydrogen storage in comparison with 2Mg(NH2)2-3LiH. The peak temperature of hydrogen desorption drops about 10 K and the peak width shrinks about 50 K compared with the neat 2Mg(NH2)2-3LiH. Its isothermal dehydrogenation and re-hydrogenation rates are respectively 2 times and 18 times as fast as those of 2Mg(NH2)2-3LiH. A slope desorption region with higher equilibrium pressure is observed. By means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) analyses, the existence of Li2BNH6 is identified and its roles in kinetic and thermodynamic enhancement are discussed.

Effects of Stoichiometry on the H2‐Storage Properties of Mg(NH2)2–LiH–LiBH4 Tri‐Component Systems

“…Apart from the phase transform event of LiBH 4 , only a single endothermic event at 176 °C is visible. This means that the dehydrogenation process of the 2:3:1 sample is a one‐step reaction as described in a previous publication . Similar to the TPD‐MS results, a shoulder peak can also be observed along with the major dehydrogenation peak in the DTA curve of the 2:3:4 sample, which also indicates that the desorption pathway of the 2:3:4 sample might be different.…”

“…During the first ten minutes, the 2:3:1 and 2:3:4 samples had the same absorption rates. The absorption rates of the 2:3:4 and 2:3 samples decelerated gradually, whereas the 2:3:1 sample maintained its fast absorption rate …”

Recent Progress and New Perspectives on Metal Amide and Imide Systems for Solid-State Hydrogen Storage

“…Varying the molar ratio of Mg(NH 2 ) 2 , LiH and LiBH 4 , the optimum molar ratio of 6:9:1 was found [119]. The stabilization of LiNH 2 , the product of 6Mg(NH 2 ) 2 + 9LiH, by adding LiBH 4 (Equation (11) (11) To understand the reason for the high dehydrogenation plateau (PCI curves) at the starting stage of dehydrogenation of 6Mg(NH 2 ) 2 + 9LiH + LiBH 4 , a systematic investigation of the influence of the reactants ratios was carried out [120][121][122]. Increasing the ratio of LiBH 4 in the system 6Mg(NH 2 ) 2 + 9LiH + xLiBH 4 to 12, the dehydrogenation enthalpy decreases to 24 kJ/mol H 2 (Figure 5a), allowing to achieve the theoretical equilibrium hydrogen pressure of 1 bar below room temperature.…”

Improved Dehydrogenation Properties of 2LiNH2-MgH2 by Doping with Li3AlH6

“…Several types of such materials mainly include microporous media that can physically adsorb hydrogen molecules at low temperatures [3], intermetallic hydrides that absorb atomic hydrogen as an interstitial, and complex hydrides that chemically absorb/desorb hydrogen [4,5]. Owing to the high hydrogen content, lightweight complex hydrides mostly containing Li, B, Na, Mg, and Al, such as alanates [ 4 ] − , are considered to be particularly promising as hydrogen storage materials [6][7][8][9][10][11][12][13][14][15][16][17]. The extensive studies of metal-N-H systems in recent years were initially prompted by Chen and coworkers, who reported the absorption and desorption of hydrogen gas by lithium nitride (Li 3 N) at high temperatures (195-255 • C) [18] according to Equation (1).…”