Alkane diols as a new organic phase change material encapsulated in densely packed and stacked carbonized microspheres for thermal energy storage

Abstract

To address the challenges of poor thermal conductivity, easy leakage, and low heat storage density in organic phase change materials (PCMs) for medium-temperature thermal storage applications, this study proposes a modular strategy for these issues. Initially, inspired by the molecular structure of polyethene glycol (PEG), alkane diols (ADs) were utilized as a novel type of PCM. Among them, docosanediol (DCD) exhibited a latent heat of 316.98 kJ kg⁻¹, surpassing high-molecular-weight PEG. Subsequently, a carbonized and densely stacked covalent organic framework (CDC) was used as a carrier to load the ADs, forming a composite PCM (cPCM). The optimized pore structure of the CDC achieves a mass loading efficiency of over 90 wt% with minimal leakage. Combined with DCD, the cPCM achieves a latent heat of 273.66 kJ kg⁻¹. Finally, a copper foil tape was applied to package the cPCM, forming a Copper@cPCM unit. Subsequent testing showed that with minor cPCM loading, the thermal release duration of the Copper@cPCM unit was twice that of an equivalent mass of pure copper foil. This work provides an innovative design for medium-temperature thermal storage systems, benefiting the development of thermal management and thermal energy storage technologies.