Performance design of high-temperature chloride salts as thermal energy storage material

The chloride salts have great potential used as high-temperature thermal energy storage (TES) medium for the concentrated solar power system. In this study, a new high-temperature energy storage ternary chloride composed of LiCl, KCl, and CaCl2 was developed based on the phase diagram generated by FactSage. The differential scanning calorimetry (DSC) technique was used to compare the two ternary chloride salts prepared by eutectic composition based on Factsage prediction. The DSC measurements showed that the melting points of these two different components were only 0.46 % and 1.64 % different from those predicted by Factsage. The thermal properties of the two ternary chloride salts were also compared. The solid and liquid-specific heat ofternary salts was determined by DSC using sapphire as the standard reference. The average specific heat of solid and liquid of salt 1 was 1.46 and 1.79 J/(g·ºC), respectively. The average specific heat of the solid and liquid of salt 2 was 0.73 and 0.95 J/(g·ºC), respectively. The vapor pressure and decomposition temperature of ternary chloride salts were investigated. The results showed that the vapor pressure of salt 1 was almost constant below 650 ºC by FactSage. Meanwhile, the TG results showed that the upper working temperature of salt 1 was 650 °C under the air atmosphere. In
addition, the ternary chloride salts after short-term cycling still exhibited excellent thermal properties, which revealed that these good thermal properties make them have broad application prospects in high-temperature thermal energy storage systems.