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

The effect of LaNi on thermal storage properties of MgH 2 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·mol −1 , which approaches to the theoretical values of MgH 2 . The isothermal measurement indicates that Mg-16 wt%LaNi can absorb 6.263 wt% H 2 within 30 min at 390 °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 Mg 2 NiH 4 , H 0.3 Mg 2 Ni and La 4 H 12.19 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.