On the reversible hydrogen storage in Mg(BH₄)₂ under moderate conditions

Abstract

Mg(BH 4) 2 contains 14.9 mass% of hydrogen and is considered as a promising hydrogen storage material. Reversible hydrogen sorption under moderate conditions represents a main challenge for Mg(BH 4) 2 being utilized for solid-state hydrogen storage. Here, we achieve the reversible storage of 4.0 mass% of hydrogen at 265°C in Mg(BH 4) 2. That is, desorption of 7.5 mass% H at 265°C under vacuum and absorption of 4.0 mass% at 265°C and 160 bar H 2. 11 B MAS NMR measurements indicate that the reversible hydrogen sorption involves the formation of a decisive intermediate which shows a major resonance with a chemical shift at-50.0 ppm. The phase evolution in the hydrogen cycles as well as the capacity loss in the hydrogen sorption cycles is discussed.

Review on Ammonia Absorption Materials: Metal Hydrides, Halides, and Borohydrides

“…Research efforts have been focused on developing and verifying onboard automotive hydrogen storage materials to meet these targets. Many kinds of complex materials have been synthesized and studied for storing a high capacity of hydrogen, such as amide/imide systems like LiNH 2 /Li 2 NH, − complex metal hydrides like LiAlH 4 − and NaAlH 4 , − and borohydrides like LiBH 4 , − NaBH 4 , − and Mg­(BH 4 ) 2 . − However, these materials require improvements of the properties for development as practical materials. For instance, the amide/imide systems form byproduct gas during dehydrogenation, complex metal hydrides are not easily reversible, and borohydrides have sluggish kinetics.…”

Core–Shell NaBH4@Na2B12H12 Nanoparticles as Fast Ionic Conductors for Sodium-Ion Batteries

“…Solid-state 11 B NMR was used to identify and quantify the relative populations of the boron species in NaBH 4 @Na 2 B 12 H 12 (Figures a and S8). The main peak at −42 ppm was attributed to [BH 4 ] − in the α-NaBH 4 phase, , while the signals at −15 and −21 ppm correspond to [B 12 H 12 ] 2– and [B 9 H 9 ] 2– . , The formation of the [B 9 H 9 ] 2– anion is due to the partial decomposition of NaBH 4 under H 2 . , …”

“…For this characterization, NaBH 4 @Na 2 B 12 H 12 powder was placed in a 10 mm diameter die and uniaxially pressed at 5 MPa for 5 min and then the pellet was placed in an asymmetric Swagelok-type cell, made of a stainless-steel foil/ NaBH 4 @Na 2 B 12 H 12 /Na/stainless and sealed in for CV measurement. 47,48 The formation of the [B 9 H 9 ] 2− anion is due to the partial decomposition of NaBH 4 under H 2 . 49,50 The surface composition of NaBH 4 @Na 2 B 12 H 12 was further investigated by FTIR spectroscopy (Figure 2b).…”