Investigation of the dehydrogenation behavior of the 2LiBH sub(4):CaNi sub(5) multicomponent hydride system

LiBH sub(4) has gained much attention as a potential hydrogen storage material due to its high hydrogen storage capacity of 18.5 wt%. However, LiBH sub(4) only releases its full hydrogen capacity at temperatures greater than 600 degree C and requires hydrogen pressures of at least 350 bar to rehydrogenate the end products. The dehydrogenation temperature can be altered by thermodynamic tuning through the addition of a reactive agent resulting in a lower enthalpy of dehydrogenation. Most multicomponent hydride systems display dehydrogenation temperatures above 300 degree C, making them less desirable for automotive applications. In this work we report the solid-state decomposition of LiBH sub(4) in the 2LiBH sub(4):CaNi sub(5) system below the LiBH sub(4) melting temperature of 270 degree C. In situ neutron diffraction measurements confirmed the decomposition took place in the solid state at 200 degree C, forming LiD, CaD sub(2), Ni sub(3)B and Ni sub(2)B phases as end products. The solid-state decomposition was further supported by SEM and TEM measurements showing the presence of nano-crystalline particles.