4-3-1　炭素材料との複合化による触媒添加MgH₂の水素吸放出サイクル安定性の向上

抄録

Magnesium hydride (MgH₂) is expected to be applied for a stationary hydrogen storage tank due to high gravimetric and volumetric hydrogen density. The hydrogen sorption kinetics has been improved by decreasing the particle size via ball milling and the addition of 1 mol% Nb₂O₅ as a catalyst. However, the hydrogen content of the MgH₂-Nb₂O₅ decreased with increasing cycle times of hydrogen absorption and desorption. In this study, various carbon materials with different structures were added to improve cycle stability of the MgH₂-Nb₂O₅. In addition, the degradation factors were clarified and the dependence on the amount of carbon materials added have been investigated. The addition of 4.5 mass% carbon materials improved the hydrogen absorption and desorption cycle stability regardless the original structure of the carbon materials. As the amount of carbon materials was reduced, the cycle stability degraded to different extents depending on the carbon materials. Further reduction to 2 mass% resulted in the diminished improvement in the cycle stability for carbon fiber. Cycle stability was found to vary with carbon materials and to be dependent on their structure and physical properties.