Properties of hydrogen storage alloy Mg_(2-x)Ag_xNi (x=0.05, 0.1, 0.5) by hydriding combustion synthesis

摘要

Mg_(2-x)Ag_xNi (x=0.05, 0.1, 0.5) prepared by hydriding combustion synthesis were investigated by means of pressure-composition isotherms, X-ray diffraction and scanning electron microscopy. The results showed that the maximum hydrogen absorption capacity of Mg_(1.95)Ag_(0.05)Ni is 3.49 mass percent and of Mg_(1.9)Ag_(0.1)Ni 3.43 mass percent at 553 K, just after synthesis without any activation; their desorption capacities are 3.31 mass percent and 3.18 mass percent, respectively. The XRD results explain that it is reasonable to add a little Ag in Mg_2Ni and the kinetics of the Mg_(2-x)Ag_xNi (x=0.05, 0.1) hydrogen storage alloy can be improved. The relationships between the equilibrium plateau pressure and temperature for Mg_(1.9)Ag_(0.1)Ni were log P(0.l MPa)=-2827/T+5.677 (523 K <= T <= 573 K) for hydriding and log P(0.1 MPa)=-3581/T+6.818 (523 K <= T <= 573 K) for dehydriding. That of Mg_(1.95)Ag_(0.05)Ni were log P(0.1 MPa)=-2725/T+5.354 (523K <= T <= 573 K) for hydriding and log P(0.1 MPa)=-3444/T+6.538 (523 <= T <= 573 K) for dehydriding.