Experimental investigation and thermodynamic assessment of the Li-Sb system

Sb and Sb-containing compounds have been attracting a great interest as promising alternative materials for commercial anodes and liquid batteries. The Li-Sb system was studies experimentally by investigating 6 alloys with X-ray diffraction measurement, scanning electron microscopy and electron probe microanalyses. Two binary phases Li2Sb and Li3Sb were confirmed to be stable in this system. Two invariant reactions L→(Sb)+Li2Sb and L+Li3Sb→Li2Sb were identified experimentally based on the microstructures of the as-cast alloys. The eutectic point was determined to be about 40 at% Li. The enthalpies of formation for Li2Sb, αLi3Sb and βLi3Sb at 0 K were calculated by means of density functional theory and the transition enthalpy between αLi3Sb and βLi3Sb was obtained. Then, the presently obtained results, combined with a critical review of literature data, were used to develop the thermodynamic description of the Li-Sb system by means of CALPHAD method. The liquid phase was treated as (Li, Li3Sb, Sb) using an associate model. The calculated phase diagram and thermodynamic properties can reproduce the available experimental data reasonably.