成果報告書詳細
管理番号20140000000158
タイトル*平成25年度中間年報 水素利用技術研究開発事業 燃料電池自動車及び水素ステーション用低コスト機器・システム等に関する研究開発 燃料電池自動車用水素貯蔵材料に関する研究開発
公開日2014/5/2
報告書年度2013 - 2013
委託先名国立大学法人九州大学
プロジェクト番号P13002
部署名新エネルギー部
和文要約
英文要約Development of lightweight hydrogen storage materials
1. Development of N-based Hydrogen Storage Systems
 We investigated the hydrogen desorption properties of the systems comprised of light metal hydrides MHx and amides M(NH2)y (M=Li, Mg and x, y=1, 2) giving four possible three-component systems.
(1) LiNH2-LiH-MgH2 system with the compositions of 1:1:1, 1:1:3, 1:3:1 and 3:1:1.
The hydrogen desorption temperature increases with the increasing molar ratio of MgH2. The weight loss of sample 3:1:1 with LiNH2 rich in composition reached to 8.0 mass% upon heating to 300°C.
(2) Mg(NH2)2-LiH-MgH2 system with the compositions of 2:3:1, 1:1:1, 2:1:3 and 9:2:9.
The desorption temperatures decreased with the decreasing of molar ratio of MgH2.
(3) Mg(NH2)2-LiNH2-MgH2 system with the compositions of 1:1:3, 1:2:7, 1:1:8 and 1:1:18.
The desorption temperatures decreased with the decreasing of molar ratio of MgH2, like the abovementioned systems.
(4) Mg(NH2)2-LiH-LiNH2 system involves Mg(NH2)2:xLiNH2:MgH2 where x=0 (binary composite), 1, 3, 4, 8 and 18. The intermediate range of LiH (x = 3 and 4) appears to be promising with approximately 10 mass% mass-loss at a temperature lower than 200°C.
 We will focus to further investigate to fine-tuning the molar composition in order to propose new hydrogen storing system(s) that could satisfy the selection criteria for on-board application.

2. Development of Ti-based BCC solid solution alloys
 Ti-based BCC alloys have the maximum hydrogen capacity around 4 wt% at ambient conditions. However, reversible capacity and cycle ability are issues to be improved. In the case of Ti-V-Cr BCC alloy, more than 1 wt% of absorbed hydrogen remains in the material after the first dehydrogenation. Because Ti-V-Cr alloys are transparent for neutron, Nb-substituted Ti-V-Cr BCC alloy was prepared and carried out neutron diffraction measurements using NOVA at J-PARC. Ti0.1V0.6Cr0.2Nb0.1D2-x consisted of two deuterides with face-centered cubic (FCC) and body-centered tetragonal (BCT) structures, respectively. Deuterium at the octahedral site of BCT lattice has a large isotropic atomic displacement parameter, which shows hydrogen shifts from the average position.
Regarding the Ti-V-Mn BCC alloy, Al-substituted alloys were investigated to improve both of reversible and maximum capacities. Al is inexpensive and is reported to have an effect of increasing hydrogen plateau pressure. When the Al content of x or y was 0.1-0.2, the Ti-V-Mn-Al alloy exhibited reversible hydrogen capacity more than 2 wt% at ambient conditions.
Transmission electron microscopy (TEM) and first-principle calculation have been conducted for the Ti-based BCC alloys. Optimum condition for the TEM observation has been investigated. The first-principle calculation on pseudo-binary system of TiH2-VH2 has been done.
Neutron diffraction/scattering measurements have been carried out on Mg-Ni nano materials and carbon-based materials. Both are synthesized under the same project.
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