Thermal storage properties of Mg-LaNi using as a solar heat storage material

The effect of LaNi on thermal storage properties of MgH2 prepared by ball milling under hydrogen atmosphere was investigated. The thermal storage properties, cyclic property and thermal storage mechanism were studied by pressure-composition-temperature (PCT), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The Van't Hoff curve indicates that the formation enthalpy of Mg-16 wt%LaNi is 74.62 kJ center dot mol(-1), which approaches to the theoretical values of MgH2. The isothermal measurement indicates that Mg-16 wt%LaNi can absorb 6.263 wt% H-2 within 30 min at 390 degrees C for the first absorption, the absorption reaction fraction within 2 min is over 90.00%, and the desorption reaction fraction within 2 min is 72.63%, increasing by 55.36% compared with that of Mg. Mg-16 wt%LaNi has better cyclic stability than that of Mg, only decreasing by 0.609 wt% after 80 cycles. The enhancement in thermal storage performances of Mg by adding LaNi is mainly ascribed to the formed Mg2NiH4, H0.3Mg2Ni and La4H12.19 during the cyclic process which act as catalysts and inhibit the growth of Mg. The above results prove that Mg-16 wt%LaNi is suitable for use as a heat storage material.