Deviceful LiCl salt hydrate confinement into a macroporous silicone foam for low-temperature heat storage application

Abstract

LiCl is a well-investigated salt hydrate for low-temperature thermal energy storage due to its high energy storage density (∼1250 Wh/kg), which, however, suffers from deliquescence. Its hygroscopicity induces relevant issues during hydration/dehydration cycles due to water vapor mass transfer, swelling, and agglomeration. Finding a proper semipermeable container that retains the salt and allows free water vapor flow would enhance the dehydration/hydration kinetics and conversion. In this study, a new promising macro-porous LiCl filled composite foams was evaluated for storing low-temperature heat below 100 °C. Composite foams at varying salt hydrate content were prepared (0–70% wt.). The optimal formulation was addressed by coupling morphological, absorption, and energy storage density performances. The morphological analysis evidenced a relationship between foam microstructure and salt hydrate content. Hydration/dehydration measurements indicate that the composite foam allows the water vapor diffusion thanks to its interconnected microporous structure, preventing mass diffusion issues. An energy storage density of up to 665 kWh/m3 was estimated. Furthermore, the relatively homogeneous dispersion of the salt hydrate filler in the matrix facilitates the hydration/dehydration process, leading to a notably less pronounced hysteresis area. Based on sorption, manufacturing, service, and handling feasibility, these results indicate this material as a potentially effective option for this application.

Keywords

• Silicone foam
• Salt hydrate
• LiCl
• Thermal energy storage