Synergistic shape-interface-channel ordering enhances solar-driven thermochemical energy storage

Solar-driven thermochemical energy storage based on salt hydrates offers high energy density and long-duration storage, providing a promising route to mitigate the temporal mismatch between renewable energy supply and thermal demand. However, sluggish reaction kinetics, poor cycle stability, and low solar utilization efficiency remain long-standing challenges. Here, we demonstrate a synergistic shape-interface-channel ordering strategy that substantially enhances thermochemical energy storage performance through rational engineering of CaCl₂-based pellets featuring red blood cell-mimic shape, nanoengineered hydrophilic interfaces, and hierarchical leaf veins-inspired channel networks. The optimized sample exhibits an ultrafast sorption rate coefficient of 0.03973 min^-1, a high sorption capacity of 885 mg g^-1, and a high energy storage density of 988.38 kJ kg^-1, with only 5.65% capacity decay over 1000 cycles (~3722 h). With further assistance of high solar absorptance of 97.72%, the desorption efficiency achieves as high as 93% within 60 min under one-Sun irradiation. This work establishes a general design paradigm for thermochemical energy storage pellets based on multiscale structural ordering, offering a pathway towards scalable solar-driven thermochemical energy storage.