Sugar alcohol-based phase change materials for thermal energy storage: Optimization design and applications

Sugar alcohols are a type of organic solid-liquid phase-change materials with high latent heat-storage capacity and low cost and have been considered as a promising candidate for low-to-medium temperature thermal energy storage. Nevertheless, sugar alcohols show inherent defects, such as low thermal conductivity, high supercooling, low thermal reliability, and easy exudation and leakage in their melting state. To overcome these inherent defects, four strategies have been summarized in this review to optimize their comprehensive performance, which include nanoadditives, porous impregnation, encapsulation technology, and molecular structure design. Combining sugar alcohols with nanoadditives was determined as the simplest and most effective way to improve the thermal response of sugar alcohols. Porous materials could enhance the thermal stability of sugar alcohols and depress their supercooling. Microencapsulation technology was determined to be an effective way to prevent the leakage of sugar alcohols during their phase transitions. The molecular structure design provided an effective method to decrease the phase-change temperatures of sugar alcohols. After the optimization by different strategies, sugar alcohols exhibit great application potential in low-to-medium temperature waste heat recovery, solar cookers, and thermoelectric power generation for industrial waste heat and solar energy storage. This review presents better understanding of designing and fabricating sugar alcohol-based composites for efficient thermal energy storage, conversion, and utilization. The future research and development direction of sugar alcohols are also prospected for designing sugar alcohol-based composites with a high latent heat capacity, a low supercooling degree, enhanced thermal conductance, and multiple functions for efficient utilization.