Degradation mechanism against hydrogenation cycles in MgPrNi ( = 0.6 and 1.0)

Sakaki, Koji*; Terashita, Naoyoshi*; Kim, H.*; Majzoub, E. H.*; Machida, Akihiko; Watanuki, Tetsu; Tsunokake, Shigeru*; Nakamura, Yumiko*; Akiba, Etsuo*

Journal of Physical Chemistry C, 118(13), p.6697 - 6705, 2014/04

https://doi.org/10.1021/jp500855d

We present an investigation of the degradation mechanism against hydrogenation cycles in MgPrNi ( = 0.6 and 1.0). MgPrNi shows significant degradation and loss of capacity after only a few cycles, while MgPrNi did not show any reduction of hydrogen storage capacity until 100 cycles. The peak broadening of X-ray diffraction patterns and accumulation of lattice strain were observed concomitantly with an increase of hydrogenation cycles only in MgPrNi. These changes were not observed in MgPrNi. In pair distribution function patterns, -dependent peak broadening was observed and it became significant with an increasing number of cycles in MgPrNi, suggesting an increase of the dislocation density. MgPrNi showed higher hardness and more pulverization upon hydrogenation than MgPrNi.