Development of covalent-organic frameworks derived hierarchical porous hollow carbon spheres based LiOH composites for thermochemical heat storage

Under the joint assistance of its excellent storage strength, accessible long storage lifespan, and high heat utilization efficiency, salt hydrate-based thermochemical heat storage (THS) materials give renewable energy an important outlet to alleviate the pressure of underutilization. Herein, an activated hollow spherical carbon (AHSC) with hierarchical porous architectures converted from covalent-organic frameworks (COFs) is constructed and utilized as the supporting matrix for LiOH·THS composite material for the first time. The obtained Li/AHSC3 composites have distinguished hydration performance while manifesting impressive storage ability up to 1916.4 kJ kg−1 with low operating temperature stemming from the collective effect of the void spherical framework, multimodal porosity, and high surface area of AHSC3. And the Li/AHSC3-40 composite with evidently progressed thermal conductivity is capable of realizing 94.5% heat preservation after twenty-five adsorption–desorption cycles, exhibiting its eminent cyclability and great heat transfer performance. This study not only brings new hope for overcoming the underutilization of low-grade heat but also may enlighten new ideas for enriching the application scenarios of COFs-derived carbonaceous materials.