High Performance Composite Thermochemical Heat Storage Materials Synthesized by Impregnation, Foaming, and Fibering: A Comprehensive Review

Heat energy is released during the reversible chemical reaction of the thermochemical heat energy storage (TCHS) system. Thermochemical heat energy uses an anhydrous salt and water vapor, releasing heat as water vapor molecules are absorbed by the anhydrous salt particles, forming a hydrated salt. The amount of heat energy released is proportional to the amount of sorbate that could be absorbed. Therefore, materials suitable for thermochemical heat storage systems are porous and highly thermally conductive to rapidly transfer the heat generated. Today, researchers and scientists are eagerly working to develop novel materials for the system to overcome the limitations of commonly used materials that hinder achieving higher performance. Thus, this review provides a comprehensive review of the methods and materials for high-performance thermochemical heat storage systems. It includes methods ranging from simple mechanical and physical mixing and blending to melt mixing, impregnation, foaming, electrospinning of composite polymers and nanofiber materials, and stabilized cyclic degradation, along with the corresponding results. The fillet materials described are also carbon-based, metallic, and MXene composites, which enhance thermal conductivity, while composite nanofibers, metal-organic frameworks (MOFs), alumina, silica, and zeolite enhance sorption capacity, owing to their high porous surface area-to-volume ratios. It is concluded that materials with optimized porous structures, cyclic stability, and improved heat transfer can be effective for the TCHS system when suitable methods are employed and chemically compatible materials are used.