Form-stable metal ion coordination organic sorbent aerogel and its application in low temperature microwave-powered sorption thermochemical energy storage

Sorption thermochemical energy storage (STES) systems utilizing hygroscopic salts are widely adopted due to their low cost and high sorbate uptake through chemisorption. However, salt agglomeration during the sorption process often hinders mass transfer, limiting energy storage capacity over repeated cycles. To address this challenge, previous research has explored sorbents incorporating nanostructured carbons, polymers, and metal-organic frameworks to confine hygroscopic salts within porous structures for STES applications. This study introduces a form-stable metal ion coordination organic (MCO) thermochemical sorbent aerogel (TSA) designed to overcome agglomeration and deliquescence issues in conventional STES systems. The MCO-TSA is synthesized via a reduction reaction between the hygroscopic salt and the carboxyl group of a polymer using a hydrothermal crosslinking technique. Furthermore, the aerogel's porosity is optimized by adjusting the freezing temperatures during synthesis, enhancing heat and mass transfer. The MCO-TSA demonstrates a high and stable water uptake capacity, exceeding 2.54 g/g during 30 cycles and rapid desorption of MCO-TSA can be achieved by microwave for the first time. This makes the MCO-TSA a promising candidate for sorption-based thermochemical energy storage systems. • A novel form stable metal ion coordination organic sorbent aerogel (MCO) is synthesized. • The MCO aerogel demonstrates exceptional water uptake capacity (2.5 g/g). • Low-power microwave heating enables rapid and uniform desorption of the MCO. • The MCO exhibits strong structural stability with minimal damage from microwave heating.