成果報告書詳細
管理番号20150000000161
タイトル*平成26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2015/6/23
報告書年度2014 - 2014
委託先名日本重化学工業株式会社
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Title: Hydrogen Utilization Technology Development,R&D for the technologies on H2 storage and H2 transport considering H2 produced by renewable energy source, etc. ,R&D for hydrogen storage materials on fuel cell vehicle technologies. (FY2013-FY2015) FY2014 Annual Report (Japan Metals & Chemical Co., Ltd, TOTOTA CENTRAL R&D LABS.,INC.)

To lower the cost of V-based BCC-type alloy, the simplification of the fabrication process of the ally was tried, i.e., the alloy would be obtained by only one step which was thermite reaction. Improved points were that the material and the shape of crusible, the reaction order and melting-point adjustment of deoxygenating agent, and the reaction order of Ti powder. As a result, the alloy which was almost close to the aiming composition was provided. Problem to be left is that Al and O as impurities are not low enough. However, it would be solved by adjusting the amount of Al and deoxygenating agent before the thermite reaction. If V content in a V-based BCC-type alloy is reduced, the cost of the alloy will be much lower. Therefore, required minimum amount of V content in the alloy was investigated. It was found that hydrogen-absorption/desorption cyclic property was remarkably worsened for the alloy with 45 at.% of V content.
As a search and development of new high-density hydrogen storage materials, properties of A15-type intermetallic compounds “V3X” were experimentally evaluated. For the V3Co alloy, the hydrogen absorption/desorption characteristics were confirmed. However, it was also found that the alloy system had enough hydrogen amounts to be stored. In addition, for the development of new materials, the phenomenon called "super abundant vacancy evoked by hydrogen" is positively utilized to absorb large amount of hydrogen.
 First-principles calculations based on density functional theory have been carried out to predict capacity and stability of hydrogen in vanadium-based hydrogen storage materials. First, hydrogenation reactions for existing A15-type compounds, V3X (X=Al, Si, Co, Ni, Ga), are investigated. Our prediction suggests that three hydride phases, V3AlH3, V3GaH3, and V3NiH4, are thermodynamically stable though hydrogen capacities of them are insufficient for practical applications. Second, the substitution of the first- and second-row elements for V is examined using first-principles molecular dynamics simulations. The substitution of Li is found to increase the hydrogen capacity to about 3 mass%. Since Li also affects the stability of hydrogen, which lowers the heat of hydrogenation -H by 13 kJ/mol H2, the second substituent is required to adjust H.
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