Properties of La0.2Y0.8Ni5−xMnx alloys for high-pressure hydrogen compressor

Hydrogen absorption/desorption properties of La0.2Y0.8Ni5−xMnx (x = 0.2, 0.3, 0.4) alloys for high-pressure hydrogen compression application were investigated systematically. The Pressure–Composition isotherms and absorption kinetics were measured at 293, 303 and 313 K by the volumetric method. XRD analyses showed that all the investigated alloys presented CaCu5 type hexagonal structure and the unit cell volume increased in both a and c lattice axes with Mn substitution. Hydrogen absorption/desorption measurements revealed that Mn could lower the plateau pressure effectively, improve the hydrogen storage capacity and absorption kinetics but slightly increase the slope of the pressure plateau and hysteresis. The study results suggest that La0.2Y0.8Ni4.8Mn0.2 is suitable for the high-pressure stage compression of the hydrogen compressor and the other two alloys, La0.2Y0.8Ni4.7Mn0.3 and La0.2Y0.8Ni4.6Mn0.4, for the preliminary stage.