Abstract: This paper is concerned about the thermal stability of a lithium carbonate-sodium carbonate (40%Li₂CO₃-60%Na₂CO₃ by mass) based binary molten salt. A static fusion method was used to prepare the salt and the salt underwent 1010 cycles over a temperature range between 400 ℃ and 600 ℃ in an automatic thermal cycle test rig. Variation in phase change parameters and chemical compositions during the thermal cycles were analyzed by using DSC and XRD, respectively. The results show that the methodology for the thermal stability works well and primary composition of the molten salt is lithium sodium carbonate (LiNaCO₃) with the peak temperature of 499.1℃ and a latent heat of 365.5 J/g. The melting(freezing) temperatures of the binary molten salt show small fluctuations during repeated thermal cycling, and the phase change latent heat is reduced by 45.3 J/g. No new compositions were detected during the thermal cycling.

Key words: Li2CO3-Na2CO3, thermal stability, thermal cycling