Hydrogen storage in thin film magnesium–scandium alloys

Abstract

Thorough electrochemical materials research has been performed on thin films of novel magnesium–scandium hydrogen storage alloys. It was found that palladium-capped thin films of Mg x Sc (1− x) with different compositions (ranging from x = 0.50 –0.90) show an increase in hydrogen storage capacity of more than 5–20% as compared to their bulk equivalents using even higher discharge rates. The maximum reversible hydrogen storage capacity at the optimal composition (Mg 80Sc 20) amounts to 1795 mAh/g corresponding to a hydrogen content of 2.05 H/M or 6.7 wt.%, which is close to five times that of the commonly used hydride-forming materials in commercial NiMH batteries. Galvanostatic intermittent titration technique (GITT) measurements show that the equilibrium pressure during discharge is lower than that of bulk powders by one order of magnitude (10 −7 mbar versus 10 −6 mbar, respectively).