Tetrahydroborates: Development and potential as hydrogen storage medium

The use of fossil fuels as an energy supply becomes increasingly problematic from the
point of view of both environmental emissions and energy sustainability. As an alternative, hydrogen
is widely regarded as a key element for a potential energy solution. However, differently from
fossil fuels such as oil, gas, and coal, the production of hydrogen requires energy. Alternative
and intermittent renewable energy sources such as solar power, wind power, etc., present multiple
advantages for the production of hydrogen. On the one hand, the renewable sources contribute to
a remarkable reduction of pollutants released to the air and on the other hand, they significantly
enhance the sustainability of energy supply. In addition, the storage of energy in form of hydrogen
has a huge potential to balance an effective and synergetic utilization of renewable energy sources.
In this regard, hydrogen storage technology is a key technology towards the practical application
of hydrogen as “energy carrier”. Among the methods available to store hydrogen, solid-state
storage is the most attractive alternative from both the safety and the volumetric energy density
points of view. Because of their appealing hydrogen content, complex hydrides and complex
hydride-based systems have attracted considerable attention as potential energy vectors for mobile
and stationary applications. In this review, the progresses made over the last century on the synthesis
and development of tetrahydroborates and tetrahydroborate-based systems for hydrogen storage
purposes are summarized.