Complex Metal Hydrides for Hydrogen, Thermal and Electrochemical Energy Storage

Abstract

Hydrogen has a very diverse chemistry and reacts with most other elements to form compounds, which have fascinating structures, compositions and properties. Complex metal hydrides are a rapidly expanding class of materials, approaching multi-functionality, in particular within the energy storage field. This review illustrates that complex metal hydrides may store hydrogen in the solid state, act as novel battery materials, both as electrolytes and electrode materials, or store solar heat in a more efficient manner as compared to traditional heat storage materials. Furthermore, it is highlighted how complex metal hydrides may act in an integrated setup with a fuel cell. This review focuses on the unique properties of light element complex metal hydrides mainly based on boron, nitrogen and aluminum, e.g., metal borohydrides and metal alanates. Our hope is that this review can provide new inspiration to solve the great challenge of our time: efficient conversion and large-scale storage of renewable energy.

Adsorption and dissociation of H2 on Al4Sim (m = 2, 3, and 4) clusters

“…The stabilities and electronic properties of the aluminum clusters can be changed significantly by doping with different atoms. The investigations on hydrogen storage properties of the mixed metal complexes can be found in recent reviews …”

“…The investigations on hydrogen storage properties of the mixed metal complexes can be found in recent reviews. 28,[33][34][35][36] It is well known that silicon and aluminum can form eutectic alloys. [37][38][39] Because Al Si alloys have high hardness, high tempera- LiH is reduced to 1.24 eV, and 0.78 eV of MgH 2 is reduced to 0.38 eV after doping silicon.…”

Mg-Based Hydrogen Absorbing Materials for Thermal Energy Storage—A Review

“…The TES system is one of the most crucial component of solar thermal power systems due to its contribution to the effective storage of thermal energy. In recent years, a great many groups have focused their research on TES which has attracted great attention [1][2][3][4][5][15][16][17][18]. In the current development of TES, researchers concentrate more attention on the low-temperature (<200 • C) heat storage.…”

Rare Earth Borohydrides—Crystal Structures and Thermal Properties

“…As a result, a large number of novel RE-borohydrides have been synthesized and more than 50 papers have been published since 2008. The majority of publications are focused on the synthesis and structural characterization of the compounds and several extensive reviews already exist [1,4,7]. In contrast, less information is available about the thermal properties and rehydrogenation behavior of pure RE-borohydrides or as part of composites.…”

“…Metal borohydrides are being intensively studied as potential hydrogen and thermal energy storage materials [1][2][3][4][5][6][7] as well as solid state electrolytes [8][9][10][11]. Alkali and alkaline earth borohydrides such as LiBH 4 and Mg(BH 4 ) 2 are of great interest due to their high gravimetric hydrogen storage capacity.…”