Filler dimensionality effect on the performance of paraffin-based phase change materials

Tough and sustainable solid-solid phase change materials achieved via reversible crosslinking for thermal management

Phase change materials (PCMs) exhibit significant potential for overcoming the issues related to thermal energy storage and management. However, they have faced persistent challenges in applications due to liquid leakage and solid rigidity. Novel tough and sustainable solid-solid phase change materials (SSPCMs) have been achieved using the designed carboxyl-epoxy group reactive system, which forms a reversible vitrimeric structure after crosslinking. It is demonstrated that the networks overcome the limitations of liquid leakage and solid rigidity, showing excellent phase stability after being heated for 5 hours with a tensile strength of 13.5 MPa and an elongation at break of 45%. The highest phase transition enthalpy of the prepared SSPCMs is 92.01 J g-1. The reversible phase transition of polyethylene glycol (PEG) segments locked within the networks enables excellent smart shape memory features. Notably, the networks can undergo rearrangement through interesterification, thereby acquiring recyclability and self-healing properties. Additionally, the thermal conductivity of the matrix is enhanced through the addition of BN. It is further demonstrated that the thermally conductive PCMs retain high toughness, recyclability and shape memory features, while simultaneously exhibiting potential thermal management capabilities.

Thermally Conductive Molten Salt for Thermal Energy Storage: Synergistic Effect of a Hybrid Graphite-Graphene Nanoplatelet Filler

Renewable energy technologies depend, to a large extent, on the efficiency of thermal energy storage (TES) devices. In such storage applications, molten salts constitute an attractive platform due to their thermal and environmentally friendly properties. However, the low thermal conductivity (TC) of these salts (<1 W m-1 K-1) downgrades the storage kinetics. A commonly used method to enhance TC is the addition of highly conductive carbon-based fillers that form a composite material with molten salt. However, even that enhancement is rather limited (<9 W m-1 K-1). In this study, the partial exfoliation of graphite to graphene nanoplatelets (GnP) in a molten salt matrix is explored as a means to address this problem. A novel approach of hybrid filler formation directly in the molten salt is used to produce graphite-GnP-salt hybrid composite material. The good dispersion quality of the fillers in the salt matrix facilitates bridging between large graphite particles by the smaller GnP particles, resulting in the formation of a thermally conductive network. The thermal conductivity of the hybrid composite (up to 44 W m-1 K-1) is thus enhanced by two orders of magnitude versus that of the pristine salt (0.64 W m-1 K-1).