Complex Hydrides for Energy Storage, Conversion, and Utilization

Abstract

functionalities and exhibit great potentials for the applications in the energy transfer chain (Figure 1).In chemistry, a hydride is a compound having negatively charged hydrogen anion. [2] Nowadays, however, hydrogenous compounds having hydrogen bonded to metals or nonmetal in ionic, metallic or covalent manner are collectively referred as hydrides. [3] Complex hydride is such a class of compound having a general formula of M(XH n ) m , where M is usually a metal cation and X is a metal or nonmetal element which sets up covalent or ionocovalent bonding with H. [4] The M[XH n ] m is H-rich and can decompose selectively to H 2 allowing complex hydrides of light-weight elements potential hydrogen storage media. As a matter of fact, since the pioneering work of Ti-catalyzed NaAlH 4 in 1997, [5] extensive investigations on hydrogen storage over alanates, [6] amide-hydride composites, [7] borohydrides, [8] amidoboranes [9] as well as metallorganic hydrides [10] were carried out and tremendous progress has been made (Figure 2). [1,4a] The break and setup of XH bonding would be endergonic and exergonic, respectively. The energy input and output in hydrogen desorption and reabsorption over a complex hydride depends strongly on its thermodynamic stability, which also offers an opportunity of using complex hydrides as thermal energy storage materials to cope up with the intermittent, fluctuating and unstable supply of renewable energies. Owning to their exclusive advantages of diversity, high energy densities and tunability, complex hydrides have been actively pursued for this application since year 2000. [11] Solid electrolytes with fast conduction of Li, Na, or Mg ions are highly demanded for all-solid-state batteries with high energy density and safety. Coincidentally, complex hydrides are composed of those cations and a relatively large sized [XH n ] anion. The coordination flexibility of the large anion with alkali or alkaline earth cation would create some favorable structural features, such as defects and/or low-barrier diffusion channels, to facilitate cation migration within the lattice of complex hydrides. [12] Starting from the finding of high Li-ion conduction in the high-temperature-phase LiBH 4 , [13] a variety of complex hydrides has been developed, some of which show superior ion conductivity to their nonhydride peers. [14] Hydrogen storage over complex hydride would undergo dihydrogen dissociation into surface H atoms followed by H Functional materials are the key enabling factor in the development of clean energy technologies. Materials of particular interest, which are reviewed herein, are a class of hydrogenous compound having the general formula of M(XH n ) m , where M is usually a metal cation and X can be Al, B, C, N, O, transition metal (TM), or a mixture of them, which sets up an iono-covalent or covalent bonding with H. M(XH n ) m is generally termed as a complex hydride by the hydrogen storage community. The rich chemistry between H and B/C/N/O/Al/TM allows complex hydrides of diverse compo...

Clean production and utilisation of hydrogen in molten salts

“…Molten salt preparation of metal hydrides should also be highly interesting for applications such as advanced catalysis 103 and energy storage. 104…”

Syntheses of Pt‐Ni Hollow Nanoalloy for Hydrogen Generation from Catalytic Hydrolysis of Ammonia Borane

“…[10] However, the lack of safe and efficient hydrogen storage method is recognized as one of the major technological barriers for the large-scale hydrogen implementation. [11] Catalyst-assisted hydrolysis of ammonia borane (AB) with releasing 3 equiv. of H 2 has been shown to be one of the promising hydrogen carriers for storage and transportation.…”

Improved hydrogen storage performances of LiAlH 4 + Mg( BH 4 ) 2 composite with TiF 3 addition

“…Alanates are reported to be the most interesting systems followed by borohydride and amide 2 . During the past decades, the Ti‐doped NaAlH 4 system has led to extensive study on alanates as a reversible hydrogen storage material 22,23 . To date, numerous researches have focused on LiAlH 4 from the group of alanates due to the inferior desorption temperature.…”