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 Li OH.THS composite material for the first time. The obtained Li/AHSC_(3) composites have distinguished hydration performance while manifesting impressive storage ability up to 1916.4 k J 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.

Fabrication of LiOH-metal organic framework derived hierarchical porous host carbon matrix composites for seasonal thermochemical energy storage

By virtue of its long lifespan and outstanding storage intensity with near-zero heat loss,salt hydrate thermochemical energy storage(TES)materials provide a feasible option for the effective use of renewable energy and overcoming its unsynchronized supply and demand.Here,an activated porous carbon originating from the zeolite imidazolate framework(ZHCM)is fabricated and served as the carbon matrix for the LiOH TES material.The as-synthesized Li/ZHCM2-40 not only has excellent storage intensity(maximum 2414.2 kJ·kg^(−1))with low charging temperature,but also shows great hydration properties stemming from the ultrahigh surface area and hierarchical porous structure of ZHCM2.Besides,this composite material exhibits superior thermal conductivity,while its storage intensity is only attenuated by 10.2%after 15 times of consecutive charge-discharge process,revealing its outstanding cycle stability.And the numerical simulation results also demonstrate its superior heat transfer performance.The developed LiOH TES composite may afford a new avenue for efficient low-grade thermochemical energy storage and liberate the possibility of further exploration of metal organic frameworks derived porous carbon matrix in the future.