Absorption-polymerization method for synthesizing phase change composites with high enthalpy and thermal conductivity for efficient thermal energy storage

Abstract

Phase change materials (PCMs) are extensively used in passive thermal management and heat storage owing to their high latent heats near phase change temperatures. However, low thermal conductivity and leakage are two persistent bottlenecks in applications of PCMs. In this study, a new absorption-polymerization method is proposed to prepare phase change composites (PCCs) with both high thermal conductivity, high enthalpy, high encapsulation ratio, and leakage-proof property. The PCCs are synthesized in two steps: (1) absorption: n-hexadecane (C16) and methyl methacrylate (MMA) are absorbed into expanded graphite (EG) network; (2) polymerization: the absorbed MMA is subsequently polymerized to encapsulate C16 and form core-shell microcapsules in the EG networks. The PCCs exhibit latent heats of 170–200 J/g, encapsulation ratios of 72–85%, and thermal conductivities of 0.8–3.9 W/(m·K). In addition, the PCCs exhibit good dynamic response and long-term cycle stability. The absorption-polymerization process is an efficient and cost-effective method of synthesizing high-performance PCCs, which is promising for various heat-related applications, such as heat collection for renewable energy, energy conservation in buildings, and thermal protection of electronic equipment. • An novel absorption-polymerization method is proposed to prepare EG/PMMA/C16 PCCs. • The PCCs exhibit both macroscopic and microscopic encapsulation structure. • The PCCs have high thermal conductivity, high enthalpy and leakage-proof property. • The PCCs have good dynamic response and long-term cyclic stability.