Crystal Structural Investigations for Understanding the Hydrogen Storage Properties of YMgNi4-Based Alloys

Toyoto Sato, Tomohiro Mochizuki, Kazutaka Ikeda, Takashi Honda, Toshiya Otomo, Hajime Sagayama, Heena Yang, Wen Luo, Loris Lombardo, Andreas Züttel, Shigeyuki Takagi, Tatsuoki Kono, Shin Ichi Orimo

Research output: Contribution to journalArticlepeer-review

Abstract

The hydrogen storage properties and crystal structures of YMgNi4-based alloys, which were synthesized from (2 - x)YNi2 and xMgNi2 (0.6 ≤ x ≤ 1.2), were investigated by pressure-composition-temperature measurements and powder neutron diffraction at a deuterium gas pressure to understand the hydrogen absorption and desorption reactions viewed from atomic arrangements around H atoms. Reducing the amounts of MgNi2, which was utilized as a Mg source in YMgNi4-based alloys, has been observed to lower the hydrogen absorption and desorption pressures and increase the hydrogen storage capacities. However, the reversible hydrogen capacity attained a maximum value of 1.2 mass % at x = 0.8 because of the formation of a thermodynamically stable hydride in which hydrogen was not released at x = 0.6. In the case of x = 0.6, the presence of excessive Y atoms around the H atoms in the hydrogen-absorbed phase would lead to the formation of a hydride with stronger interaction between Y and H because of the affinity between them. Moreover, the presence of small amounts of D atoms with short interatomic D-D distances (1.6 and 1.9 Å) in the deuterium-absorbed phase (Y0.81Mg1.19Ni4.00D3.35 and Y1.06Mg0.94Ni4.00D3.86) at <5 MPa and 323 K was proposed by the crystal structural investigations. The D atoms with short D-D interatomic distances were located in the same local atomic arrangements of D atoms in a deuterium-absorbed phase, which were formed at a higher-pressure range, and had higher hydrogen storage capacities than the deuterium-absorbed phases in this study.

Original languageEnglish
Pages (from-to)31192-31198
Number of pages7
JournalACS Omega
Volume5
Issue number48
DOIs
Publication statusPublished - 2020 Dec 8

ASJC Scopus subject areas

  • Chemistry(all)
  • Chemical Engineering(all)

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