Mg/Al系積層膜の水素吸蔵放出特性評価

抄録

Hydrogen storage alloys that store hydrogen in the form of metal hydrides are attracting attention as a means of storing and transporting hydrogen. Mg-based hydrogen storage alloys are expected to be used in the application because Mg is typical lightweight material and abundant resource in the earth. Its hydrogen storage capacity is 7.6 wt. %, which is large among the alloys, while it need to improve its reaction speed and high desorption temperature for the application. In this research, we prepared Mg/Al/Pd and Al/Mg/Pd layered thin films with pulsed laser deposition (PLD) method and the influence of the difference in stacking order and Mg layer thickness on the hydrogen storage and release characteristics were investigated. The target values of Mg layer were 300 nm and 500 nm, Al layer was 60 nm, and Pd layer was 10 nm. X-ray diffraction (XRD) analysis showed that MgH2 were produced in all samples after activation at 200℃ under hydrogen pressure of 0.85 MPa. Differential scanning calorimetry (DSC) resulted that Mg300/Al/Pd, Mg500/Al/Pd, Al/Mg300/Pd, Al/Mg500/Pd released hydrogen at 230℃, 235℃, 210℃ and 195℃, and the hydrogen desorption temperature decreased about 200℃. The results of Pressure-Composition-Temperature (PCT) measurements showed that Mg300/Al/Pd, Mg500/Al/Pd, Al/Mg300/Pd, Al/Mg500/Pd stored hydrogen up to 2.79 wt.%, 1.53 wt.%, 2.16 wt.%, and 1.59 wt.% respectively at 200℃ although Mg500/Al/Pd and Al/Mg500/Pd didn’t desorb hydrogen during PCT measurements.