Function of aluminum in crystal structure of rare earth–Mg–Ni hydrogen-absorbing alloy and deterioration mechanism of Nd 0.9 Mg 0.1 Ni 3.5 and Nd 0.9 Mg 0.1 Ni 3.3 Al 0.2 alloys
| Autor: | Takashi Yamazaki, Shigekazu Yasuoka, Kyosuke Kishida, Kai Takuya, Haruyuki Inui, Jun Ishida, Kajiwara Takeshi, Shuuichi Doi |
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| Rok vydání: | 2017 |
| Předmět: |
Materials science
Hydrogen Renewable Energy Sustainability and the Environment Hydride Metallurgy Alloy Energy Engineering and Power Technology chemistry.chemical_element 02 engineering and technology Crystal structure engineering.material 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences 0104 chemical sciences Amorphous solid Fuel Technology Lattice constant Nickel–metal hydride battery chemistry Aluminium engineering Composite material 0210 nano-technology |
| Zdroj: | International Journal of Hydrogen Energy. 42:11574-11583 |
| ISSN: | 0360-3199 |
| DOI: | 10.1016/j.ijhydene.2017.02.150 |
| Popis: | We investigated in detail the effect of incorporating Al in the crystal structure of rare earth–Mg–Ni hydrogen-absorbing alloys, which were developed as candidate materials for the metal hydride (MH) negative electrode in commercial Ni–MH batteries, using synchrotron powder X-ray diffraction. Partially substituting the Ni part with Al changes the lattice parameter of the major A2B7 phase, eliminating a mismatch between the AB2 units and the AB5 units. The change of the lattice parameter in the alloy leads to good hydrogen reversibility and good durability. Furthermore, we observed the alloy after 30 hydrogen absorption–desorption cycles using a scanning transmission electron microscope image. Consequently, we found that the surface layer of the Nd0.9Mg0.1Ni3.5 alloy had an amorphous state, while the surface layer of the Nd0.9Mg0.1Ni3.3Al0.2 alloy did not. We confirmed that the deterioration mechanism of the Nd0.9Mg0.1Ni3.3Al0.2 alloy was due to partial expansion of the AB2 unit along the c-axis; the local area of deterioration expanded during the cycling period. |
| Databáze: | OpenAIRE |
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