Solar-driven thermochemical energy storage using porous copper-cobalt aluminate redox materials

Thermochemical energy storage (TCES) is a high-density, lossless solution for managing dispatchable solar energy and industrial waste heat. A critical challenge in its development is scaling promising lab-scale materials to operable systems, which requires a deep understanding of their performance under realistic reactor conditions. This study bridges this gap by investigating a novel porous copper-cobalt aluminate (Co₅Cu₁@Al₂O₃), engineered via sol-gel impregnation to enhance redox kinetics, thermal stability, and gas-solid interactions. We rigorously evaluated the material in a dual-reactor system, directly comparing concentrated solar irradiation with conventional furnace heating. In situ gas chromatography provided real-time monitoring of oxygen evolution during redox cycles between 580 and 900 °C. At an optimal Air/Ar ratio of 100/200, the material achieved high energy storage densities of 280.24 J/g (solar) and 287.79 J/g (furnace). Remarkably, increasing the flow rate under solar heating boosted the storage density to 438.51 J/g, a value that surpasses all previously reported benchmarks for porous transition metal oxides. The composite maintained excellent structural integrity and redox durability over multiple cycles, with an energy release efficiency exceeding 98 %. These results underscore the critical synergy between advanced material design, optimized gas flow regimes, and tailored reactor configuration for developing viable high-temperature solar TCES systems.