Thermal storage properties of Mg with synergistic effect of LaNi and TiH₂

The effect of LaNi and Ti on thermal storage properties of MgH₂ was investigated. The thermal storage performances of Mg are significantly improved by adding LaNi and Ti. The pressure–composition–temperature (PCT) curves indicate that the formation enthalpy for Mg-15 wt%Ti-5 wt%LaNi sample is 73.00 kJ·mol⁻¹, which approaches to the theoretical values of pure MgH₂. The isothermal measurement indicates that, for the Mg-15 wt%Ti-5 wt%LaNi, the first absorption reaction fraction within 2 min is 93.77%, increasing by 0.32%, 0.24% and 0.08% compared with those for Mg, Mg-5 wt%LaNi and Mg-15 wt%Ti, respectively. The first desorption reaction fraction within 2 min is 73.18%, increasing by 55.91%, 9.79% and 8.12% compared with those for Mg, Mg-5 wt%LaNi and Mg-15 wt%Ti, respectively. Moreover, Mg-15 wt%Ti-5 wt%LaNi has the best cyclic stability in all the samples. The thermal storage performances of Mg by adding both LaNi and Ti are improved mainly ascribed to synergistic effect of in situ formed La₄H_12.19, Mg₂NiH₄, H_0.3Mg₂Ni and TiH₂ particles during cyclic process. The above analysis demonstrates that Mg-15 wt%Ti-5 wt%LaNi is suitable for using as a heat storage material.