Design of Refined Quaternary Electrolyte LiF-LiCl-LiBr-LiI Used for the Liquid Metal Battery.

The advanced electrolyte of liquid metal battery should have low melting point, low ionic solubility, low viscosity, high electric and thermal conductivities, and a suitable density between anode and cathode for declining the operating temperature and realizing the goal of saving-energy. In this study, an excellent quaternary LiF-LiCl-LiBr-LiI (9.1 : 30.0 : 21.7 : 39.2) electrolyte is refined by using thermodynamic models to balance various properties of LiX (X=F, Cl, Br, I) and meet the requirement of advanced electrolyte of liquid metal battery. The refined properties of electrolyte correspond to 2.398 g/cm3 for density, 0.286 mol% for solubility, 4.486 Ohm-1 cm-1 for ionic conductivity, and 0.609 W m-1 for thermal conductivity. The measured melting point is 609.1 K, which is lower than the current operating temperature of 723 K for the lithium-based liquid metal battery. The refined electrolyte consisted by quaternary halide molten-salt provides important references for preparing the advanced liquid metal battery.

Mechanism exploration of the enhancement of thermal energy storage in molten salt nanofluid.

Enhancement of the specific heat capacity of a molten salt-based nanofluid is investigated via molecular dynamics (MD) simulations. The results show that the addition of nanoparticles indeed enhances the specific heat capacity of the base fluid. Combining the analysis of potential energy and system configurations, the main reasons responsible for the enhancement of the specific heat capacity of the nanofluid are revealed. Different from previous reports on nanofluids, there is no correlation between the specific heat capacity and the potential energy magnitude of the nanofluid system. It is noticed that the trend of change in the potential energy with nanoparticle loading is only related to the relative magnitude of the nanoparticle and the base fluid potential energy. Moreover, the introduction of nanoparticles introduces an extra force into the system and causes the formation of a compressed layer around the nanoparticle. This structure is tighter than the pure base fluid and requires more energy to be broken. The extra energy used to break this structure can act to enhance the specific heat capacity of the nanofluid. Our research reveals the mechanism behind the specific heat capacity enhancement and guides the prediction of thermal properties and material selection of the nanofluid.