Development of pomegranate-type CaCl₂@C composites via a scalable one-pot pyrolysis strategy for solar-driven thermochemical heat storage

This study aimed to develop a novel sorbent for solar driven thermochemical heat storage. The core-shell CaCl₂@C composites with tunable CaCl₂ loading were obtained by a facile one-pot pyrolysis strategy, with the low-cost and abundant coal tar being used as the carbon precursor. CaCl₂ was confined to the mesopores and macropores of the carbon shell, which led to a better structural stability than that of the impregnated sorbent. Moreover, the light-to-heat conversion of carbon shell was followed by the thermal energy storage by calcium chloride. In addition, the surface temperature of Ca/CT200-700 under the simulated sunlight of 1000 W/m² increased to 75 °C. After irradiation for 230 min, the volumetric energy storage density of Ca/CT200-700 was 254 kWh/m³, with the water loss of 0.81 g-H₂O/g-sorbent. This core–shell sorbent will provide new insights into the field of solar thermal conversion and storage.