In-situ investigation of the hydrogen release mechanism in bulk Mg2NiH4

Xuan Quy Tran, Stuart D. McDonald, Qinfen Gu, Tomokazu Yamamoto, Koji Shigematsu, Kohei Aso, Eishi Tanaka, Syo Matsumura, Kazuhiro Nogita

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)


Hydrogen storage is an important aspect to enable the so-called hydrogen economy. Mg-Ni alloys are among the most promising candidates for solid-state hydrogen storage systems yet many questions remain unanswered regarding the hydriding/dehydriding mechanism of the alloys. Mg2NiH4 particularly has received much attention both for its potential as a hydrogen storage medium and also exhibits interesting properties relating to its different polymorphs. Here, the dehydriding mechanism in bulk Mg2NiH4 is investigated using in-situ ultra-high voltage transmission electron microscopy (TEM) combined with Synchrotron powder X-ray diffraction (XRPD) and differential scanning calorimetry (DSC). We find that the hydrogen release is based on a mechanism of nucleation and growth of Mg2NiHx (x∼0–0.3) solid solution grains and is greatly enhanced in the presence of crystal defects occurring as a result of the polymorphic phase transformation. Also importantly, with atomic resolution TEM imaging a high density of stacking faults is identified in the dehydrided Mg2NiHx (x∼0–0.3) lattices.

Original languageEnglish
Pages (from-to)130-138
Number of pages9
JournalJournal of Power Sources
Publication statusPublished - Feb 15 2017

All Science Journal Classification (ASJC) codes

  • Renewable Energy, Sustainability and the Environment
  • Energy Engineering and Power Technology
  • Physical and Theoretical Chemistry
  • Electrical and Electronic Engineering


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