Phase Equilibria in the LiBr–Li2CO3–Li2SO4 System and Analysis of the Systems LiHal–Li2CO3–Li2SO4 (Hal = F, Cl, Br, I)

Phase equilibria in the ternary salt system LiBr–Li2CO3–Li2SO4 were studied by differential thermal analysis. The coordinates of a eutectic were found to be 65.0 mol % LiBr, 20.0 mol % Li2CO3, 15.0 mol % Li2SO4, and a melting point of 429°C. Data on the binary systems LiBr–Li2CO3 and Li2CO3–Li2SO4 were refined. The specific enthalpy of melting of the eutectic (97.0 ± 2.3 kJ/kg) was found by differential scanning calorimetry on a DSK-500 setup. The series of the systems LiHal–Li2CO3–Li2SO4 (Hal = F, Cl, Br, I) was analyzed, and models of the liquidi of the systems LiBr–Li2CO3–Li2SO4 and LiI–Li2CO3–Li2SO4 were constructed. Before experimental investigation, the expected melting points of the eutectics in these systems were calculated from the dependences on the atomic number of the halogen and on the melting point of the eutectics in the faceting binary systems in the above series. The eutectic alloy in the salt system LiBr–Li2CO3–Li2SO4 can be recommended for the possible use as a fusible electrolyte for chemical power sources.