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.

Strong Dependence of Thermal and Magnetic Properties on Valence Electron Structures in R2Co17 (R = Rare Earth) Intermetallics.

The valence electron structures (VESs) and thermal and magnetic properties of R2Co17 intermetallics with rhombohedral (R = Ce, Pr, Nd, Sm, Gd, and Tb) and hexagonal (R = Y, Dy, Ho, and Er) structures are studied systematically with the empirical electron theory of solids and molecules (EET). The calculated values, which cover the bond length, cohesive energy, melting point, magnetic moment, and Curie temperature, fit the experimental ones well. The study reveals that the thermal and magnetic properties of R2Co17 are strongly related to their VESs. It shows that the properties of R2Co17 can be modulated by covalence electron number nc/atom for cohesive energy and melting point, the 3d magnetic electrons of various Co sublattices for magnetic moment, the electron transformation from covalence electrons to 3d magnetic electrons for the moments of various Co sublattices, and molecular moment for Curie temperature. The structural stability of R2Co17 depends upon the distribution probability of covalence electrons on various bonds. The pseudobinary La-Co 2:17 phase can be stabilized by doping a transition metal into La2Co17 by modulating the covalence electron number per Co atom to be very close to the stable nc/Co range of rhombohedral LR2Co17 (LR=light rare earth).