Metal-organic framework-derived graphene porous carbon matrix based lithium hydroxide chemical heat storage composite materials for residential heating

Abstract

As a promising candidate for converting renewables into chemical energy, lithium hydroxide based chemical heat storage (CHS) materials have gained great investigate enthusiasm by virtue of their outstanding storage capacity and long storage lifespan. But salt hydrates still cannot get rid of the inherent shortcomings of poor thermal conductivity, sintering, low hydration rate, and serious heat storage density degradation, Hence, it is highly desirable to create a salt hydrate CHS material that can achieve improved thermal conductivity, heat storage capacity and water storage content while maintaining good cycle stability for efficient utilization of low grade heat and residential heating. Here, we develop a lithium hydroxide composite CHS material with zeolitic imidazolate framework produced graphene-based (ZIF-8/GO) porous carbon templates as the host porous carbon matrix (ZHPCM). This Li/ZHPCM composite has huge storage strength (Max. 1483.8 kJ kg−1), low reaction activation energy and high hydration capacity attribute to the adequate specific surface area and massively porous of ZHPCM, which not only boosts the spreading of lithium hydroxide, but also assuages the sintering of lithium hydroxide, thus increasing the conversion rate of LiOH to LiOH·H2O, and ultimately lead to an improvement in the storage strength. Moreover, compared to lithium hydroxide, this Li/ZHPCM composite shows remarkable cycle property for 15 times of hydration conversion without conspicuous weakened and good thermal conductivity. Besides, the calculated energy barrier that Li/ZHPCM(800)-50 (35.7 kJ mol−1) needs to overcome is also significantly lower than that of lithium hydroxide (50.7 kJ mol−1), which not only implies that the resistance to the reaction of Li/ZHPCM(800)-50 is smaller, but also further proves the important role of ZHPCM(800) in improving the performance of lithium hydroxide. This novel LiOH composite CHS material may paves a new way for residential heating and the further application of ZHPCM in the future.