Experimental Investigation on Thermochemical Energy Storage Performance of Al2O3/MgO Co-Doped Calcium-Based Composites for Solar Thermal Applications

Abstract

In calcium cycle (CaO/CaCO₃)-driven thermochemical energy storage systems, the thermal storage capacity of calcium-based materials decreases significantly during cycling, which is mainly attributed to high-temperature sintering and pore structure degradation. To address the aforementioned issues, this study synthesized acetic acid-modified Al₂O₃/MgO synergistically stabilized calcium-based thermal storage materials (Ca/Mg/Al molar ratios = 100:8:8, 100:8:10, 100:8:12, 100:8:14) via a wet blending method and investigated the effects of Al₂O₃/MgO doping ratios on the thermal storage performance. Results demonstrated that the optimal molar ratio of Ca:Mg:Al = 100:8:12 (labeled Ca₁₀₀-Mg₈-Al₁₂) exhibits a 90.81% improvement in cyclic stability of thermal storage compared to the unmodified Ca₁₀₀ sample. Microstructural characterization revealed that the calcium-based synthetic material possessed abundant micropores, smaller particle sizes, and a more uniform particle size distribution. The calcium-based synthetic material holds significant potential for broad applications in thermochemical energy storage systems.