Molecular Dynamics Simulations of Nitrate/MgO Interfaces and Understanding Metastability of Thermochemical Materials

We explore the role of molten nitrate interfaces on MgO surface treatment for improving the reversibility of thermochemical energy storage via sorption and desorption of water or CO2. Our molecular dynamics simulations focus on melts of LiNO3, NaNO3, KNO3, and the triple eutectic mixture Li0.38Na0.18K0.44NO3 on the surface of MgO to provide atomic scale details of adsorbed layers and to rationalize interface energies. On this basis, a thermodynamic model is elaborated to characterize the effect of nitrate melts on the dehydration of Mg(OH)2 and to quantitatively explain the difference in dehydration temperatures of intact and LiNO3-doped Mg(OH)2.