Correlation of Valence Electron Structures and Thermal and Electric Properties in Li∥Sb-Based Liquid Metal Batteries

The valence electronic structures and the thermal and electric properties of electrodes in Li∥Sb-based liquid metal batteries are systematically studied with the empirical electron theory. The physical properties, including the cohesive energy, melting point, electric potential, and open-gate voltage, are revealed to closely correlate to the valence electron structures. These calculated physical properties agree well with the experimental ones. The studies reveal that the melting points of the cathode and anode reduce with a decrease in valence electrons and covalent electrons by alloying of the cathode and intermetallic compounding of the anode. Additionally, the melting point of the molten salt electrolyte reduces on increasing the averaged anion radius and compositing the multiple halide salts. The high open-gate voltage can be realized by decreasing the lattice electrons of the anode product. The solubility of Li ions in molten salt electrolytes follows a rigid model based on the ionic size and the liquid density. Li-ion solubility reduces on increasing the mixture of molten salts from binary to quaternary. By adjusting the valence electron structure of metallic electrodes and the mixture of molten salt electrolytes, an advanced Li∥Sb-based liquid metal battery can be obtained, having a low melting temperature, low solubility of Li ions in molten salts, high open-gate voltage, and high stability of the cathode/molten salt/anode-layer structure.