Multifunctional SrFeO3-δ@Al composite macrocapsules for synergistic high-temperature thermal storage and oxygen separation

Developing high-performance materials for integrated thermal energy storage and oxygen production is critical for advancing sustainable energy systems. Aluminum as heat storage phase change materials has a high latent heat storage density, but suffering from the leakage problems. The SrFeO 3− δ (SFO) oxygen carrier exhibits exceptional redox activity for air separation with a high reduction enthalpy of 96 kJ/mol. In this study, we report a multifunctional composite macrocapsules composed of SFO shell and metallic aluminum core, engineered to synergistically combine thermochemical, latent, and sensible heat storage with air separation capabilities. The composite macrocapsule has a high heat storage capacity of 435.9 J/g at a temperature duration of 873 K to 1073 K and an oxygen storage capacity of 1.69 wt%. After conducting 50th thermal cycles in air for the composite macrocapsules, the samples remain unbroken and the oxygen absorption/release and heat storage capacities remain stable. The synergy between the thermochemical properties of SFO and the phase change heat storage of aluminum enables dual functionality, i.e., efficient high-temperature heat storage and on-demand air separation for chemical looping applications. This work provides a scalable paradigm for multifunctional energy materials, bridging the gap between thermal management and carbon neutral technologies.