Overview of A5B19 phase metal hydrides
This chapter provides an overview to A5B19 phase metal hydrides that can be used for hydrogen storage.
Investigation of the binary La–Ni system has shown that different phases built from the intergrowths of [AB5] and [A2B4] building blocks leads to interesting hydrogen storage properties. The system A5B19 is particularly promising since it has a stoichiometry close to the AB5 one though slightly richer in rare earth. Moreover, the possibility to replace part of the heavy rare earth by light element such as Mg within the [A2B4] block opens new route to prepare efficient storage material with suitable sorption properties. Such improvement in the thermodynamic and storage properties of these A5B19 phases has conducted to large investigations on these systems especially in the field of electrochemical energy storage as negative electrode for Ni-MH batteries.