Studies on heat capacities and thermal analysis of Li–Mg–N–H hydrogen storage system

The heat capacities of LiNH 2 and Li 2 MgN 2 H 2 were measured by a modulated differential scanning calorimetry (MDSC) over the temperature range from 223 to 473 K for the first time. The value of heat capacity of LiNH 2 is bigger than that of Li 2 MgN 2 H 2 from 223 to 473 K. The thermodynamic parameters such as enthalpy ( H – H 298.15 ) and entropy ( S – S 298.15 ) versus 298.15 K were calculated based on the above heat capacities. The thermal stabilities of them were investigated by thermogravimetric analysis (TG) at a heating rate of 10 K min −1 with Ar gas flow rate of 30 mL min −1 from room temperature to 1,080 K. TG curves showed that the thermal decomposition of them occurred in two stages. The order of thermal stability of them is: Li 2 MgN 2 H 2 > LiNH 2 . The results indicate that addition of Mg increases the thermal stability of Li–N–H system and decrease the value of heat capacities of Li–N–H system.