System Development And Characterization Of Hydrogen Storage Alloy Material

Hydrogen storage material is the new type functional material developed along with hydrogen energy utilization in recent thirty years. It is an important alternative material as hydrogen storage and deliver carrier in the hydrogen energy system. The combination of hydrogen storage and transportation will be optimal partner of hydrogen energy development and utilization in the 21st century. Hydrogen storage material takes an important part in the field of high technology. Therefore, research and development of hydrogen storage materials become a hot topic in the world.When discussing the so many parameters of the properties of hydrogen storage materials, P-C-T curve is the most important parameter. According to analysis of the traits of hydrogen storage materials in the process of hydrogen storage, an apparatus for measuring hydrogen storage properties is designed and assembled. The theory of the apparatus is simple, the measurement accuracy is high, and the operation of the apparatus is simple and convenient.We chose MmNi3.6Mn0.4Al0.25Co0.75, La1.5Mg0.5Ni6.7Al0.3, Ti0.8Zr0.2V2.7Mn0.5Cr0.7 Ni1.75 as the alloy samples, and we take X-ray diffraction test. The XRD analysis shows that the intensity of the peaks of X- ray diffraction gets sharp and strong, which indicates that the crystal structure of alloy samples is stable.Applying the designed apparatus to test samples, the structure indicates that for the same kind of hydrogen alloys, the plateau pressure increases as the increase of the temperature, but the maximum hydrogen storage capacity decreases. Meanwhile the delay of hydrogen storage alloys reduces dramatically. Among the three alloy samples, the maximum absorption amount of Ti0.8Zr0.2V2.7Mn0.5Cr0.7 Ni1.75 was the most, which amounts to 1.92wt% at 60℃. But the plateau pressure is a little higher compared with the other two alloys, between 1atm and 4atm. The maximum amount of hydrogen storage of alloy MmNi3.6Mn0.4Al0.25Co0.75 is only about 0.64%. The property of hydrogen storage and the plateau pressure are both smaller, which is 1atm at 60℃. The maximum absorption amount of the annealed La1.5Mg0.5Ni6.7Al0.3 is smaller than 2wt%, and absorption plateau pressure is between 1atm and 2.5atm. Studies of thermodynamics indicate that the enthalpy of different hydrogen storage alloy is invariable when temperature changed, and for different kinds of hydrogen storage alloys, the change of the standard enthalpy H? differs a little. Among the three alloy samples, the enthalpy and the entropy of La1.5Mg0.5Ni6.7Al0.3was the most, which amounts to -29.79 kJmol-1 and -125.67Jmol-1K-1; the enthalpy and the entropy of Ti0.8Zr0.2V2.7Mn0.5Cr0.7 Ni1.75 was the least, which amounts to -19.28kJmol-1 and -81.01Jmol-1K-1.