ALUMINUM-BASED MATERIALS FOR THERMOCHEMICAL ENERGY STORAGE APPLICATIONS

The main purpose of this PhD work is the study of a new class of materials for thermal energy storage. The research for new materials for thermochemical storage (TCM), needs to develop systems based on a chemical reaction that can store/release high amounts of thermal energy, exhibit a sufficient degree of reversibility (direct and reverse reactions must occur cyclically), and ensure long-term chemical stability of reactants and products. Calcium aluminates are widely studied compounds for the production of cements. In particular, the focus has been centered on tricalcium aluminate hexahydrate (Ca3Al2O6·6H2O) as a novel, low-cost, non-toxic material for energy storage applications. Such materials exhibit high heats of hydration and dehydration temperatures in the 200-350°C range, which is lower than that of more conventional materials investigated for medium temperature thermochemical storage. The development of TCMs operating at these temperatures is very limited: energy storage in the 200-300°C range is an excellent solution for the recovery of waste heat from high-temperature processes, that are the main emitters of energy at medium temperature. The work studies the material synthesis and morphological, structural and thermochemical characterization of the most thermodynamically stable compound belonging to the calcium aluminate family, the tricalcium aluminate Ca3Al2O6.