Synthesis And Properties Of Mg-based Hydrogen Storage Alloys

The problems of environment and energy sources were regarded at present, therefore, the hydrogen energy was favored by the scientists all over the world because of its cleanness. As the storage and transportation medium of hydrogen, the hydrogen storage materials research became a very pop item. For the great hydrogen storage capacity, low density and inexpensive value, the Mg-based hydrogen storage materials were thought as the most promising one, but its thermodynamics and kinetics properties in hydrogen absorbing process were worse and it's antierodibility in lye was bad too. In this study, three kinds of Mg based hydrogen storage (Mg2Ni, Mg-Al-Ni series and Mg-Ni-Cu series) were prepared by two step method (engine activation and sinter in solid), and three kinds of alloys (Mg2Ni, Mg-Al-Ni and Mg-Ni-Cu series) were synthesized by mechanical alloying. After that, XRD, SEM, microstructure, granularity, electrochemistry properties and hydrogenation properties (including the absorption velocity curve, absorption and desorption PCT curves of samples) analysis were employed, the results showed that:①5 kinds of alloys (Mg2Ni, Mg-Al-Ni series,Mg-Ni-Cu series) can be synthesized by two step method. XRD results showed that all the alloys'main phase was Mg2Ni, and the other hydrogen storage phase (Mg3AlNi2) was also found in Mg-Al-Ni alloys, at the same time the hydrogen storage phase (Mg2Cu) was also found in Mg-Ni-Cu alloys. The hydrogen storage analysis indicated that the Mg2Ni alloys'hydrogen storage properties was 2.52wt% at 400℃. Its cycle stabilities were bad. The analysis showed that the substitution of Mg by Al and the substitution of Ni by Cu can improve the alloys'cycle stabilities properties. The desorption ratio was increased to 70%.②6 kinds of alloys (Mg2Ni, Mg-Al-Ni series,Mg-Ni-Cu series) can be produced by mechanical alloying. XRD results showed that the six kinds of alloys'main phase were Mg2Ni, and the other hydrogen storage phase (Mg3AlNi2) was also found in Mg-Al-Ni alloys, at the same time the hydrogen storage phase (Cu11Mg10Ni9) was also found in Mg-Ni-Cu alloys. The hydrogen storage analysis showed that the alloys produced by mechanical alloying can absorb hydrogen at lower temperature. The Mg2Ni alloys'hydrogen storage properties was 3.41wt% at 350℃, but it's desorption ratio was bad. The analysis showed that the substitution of Mg by Al and the substitution of Ni by Cu can improve the alloys'absorption plateau and desorption properties at low temperature.In the end, the manufacturing technology parameters and hydrogen storage phase Mg3AlNi2 relation between hydrogenation was discussed.