Property Changes of Some Hydrogen Storage Alloys upon Hydrogen Absorption-Desorption Cycling

摘要

Hydrogen absorption-desorption cycling induced by pressure change in a closed system were carried out with LaNi_5, La_(0.7)Ce_(0.3)Ni_4Cu and TiFe_(0.9)Ni_(0.1) alloys. PC isotherms measured during the cycling showed some changes in hydrogen storage capacity, plateau pressure and hysteresis of the alloys. . The half capacity life of LaNi_5 alloy can be projected as 70,000 cycles for room temperature pressure cycling. When La_(0.7)Ce_(0.3)Ni_4Cu alloy was pressure cycled both of the plateau pressures were decreased significantly and continuously. TiFe_(0.9)Ni_(0.1) alloy showed a good resistance to cyclic degradation. Heat treatments of the degraded alloys under 1 atm of hydrogen gas recovered most of the hydrogen storage properties to the initial level even though they were degraded again more rapidly upon subsequent cycling.