Enhancement effect of Ce hydride on hydrogen storage performance of Mg(NH2)2-2LiH

Abstract

Because Mg(NH 2 ) 2 -2LiH system has a high hydrogen storage capacity and a mild hydrogen release temperature around 125 °C, it can be used as a new generation of on-board hydrogen storage material , but the hydrogen absorption and release kinetics still have great obstacles. In this paper, CeH 2.51 , a rare earth hydride, was used as a modified catalyst to improve its hydrogen storage performance for the first time. The experimental results showed that the addition of CeH 2.51 can significantly improve the hydrogen absorption/desorption kinetics and cycle performance compared with that of the pristine sample Mg(NH 2 ) 2 -2LiH. And the sample doped with 7.5 wt% CeH 2.51 shows the best comprehensive performance. The initial hydrogen release and absorption temperatures drops to 110 °C and 60 °C, respectively, and the activation energy of hydrogen release decreased from 120.0 kJ/mol to 102.5 kJ/mol, the hydrogen storage capacity of has almost no decay after 10 absorption/desorption cycles. In addition, the mechanism of CeH 2.51 improving the hydrogen storage performance of Mg(NH 2 ) 2 -2LiH was also clarified by various characterizations. • CeH 2.51 was used as a modified catalyst to improve Mg(NH 2 ) 2 -2LiH hydrogen storage performance. • The initial hydrogen release and absorption temperatures are reduced to 110 °C and 60 °C, respectively. • No cycling degradation occurred after 10 times absorption/desorption cycles. • CeH 2.51 changed the phase structure of the hydrogen release product to promote the hydrogen absorption reaction.