The growing global energy demand and the intermittent nature of renewable energy sources have driven the need for efficient thermal energy storage solutions. Phase change materials (PCMs), known for their ability to store and release heat during phase transitions, are crucial for addressing the temporal mismatch between energy supply and demand. Among various PCMs, polyethylene glycol (PEG) is favored for its high energy density and environmental friendliness. However, PEG's practical application is limited by its low thermal conductivity, significant supercooling, and poor photothermal conversion efficiency. To overcome these challenges, researchers have explored encapsulating PEG within porous scaffolds to enhance its thermal properties and application capabilities.
Inspired by the hollow skeletal structure of bird bones, which optimizes oxygen storage and respiratory efficiency, researchers from the University of Science and Technology Beijing developed a 3D hollow diamond-enhanced PEG composite PCM. The composite, HDF/PEG, leverages the excellent thermal conductivity of diamond and the advantages of a 3D interconnected structure to create a high-conductivity transport network. The study details the fabrication process of the HDF skeleton using microwave plasma chemical vapor deposition (CVD), laser perforation, and acid immersion, followed by the encapsulation of PEG2000 within the HDF structure.
The results demonstrate that the HDF/PEG composite significantly outperforms pure PEG2000 in several critical aspects:
- Enhanced Thermal Conductivity: The thermal conductivity of HDF/PEG increased by 378%, reaching 1.458 W/(m·K), compared to 0.305 W/(m·K) for pure PEG2000.
- Superior Latent Heat Storage: Despite a slight decrease in latent heat (111.48 J/g for HDF/PEG vs. 152.06 J/g for PEG2000), the composite effectively minimizes the latent heat difference, reducing it from 12.61 to 0.17 J/g.
- Reduced Supercooling: The degree of supercooling decreased from 19.1 °C for PEG2000 to 15.2 °C for HDF/PEG.
- Excellent Photothermal Conversion: HDF/PEG achieved a photothermal conversion efficiency of 86.68%, significantly higher than PEG2000.
- Enhanced Thermal Management: The composite extended the temperature cycling time of electronic components by 4 times for heating and 2.3 times for cooling.
The HDF/PEG composite offers an integrated solution for solar energy collection, photothermal conversion, heat dissipation in electronic components, and thermal energy transfer/storage. This innovative approach not only enhances the thermal performance and application efficiency of PCMs but also provides a new strategy for designing and fabricating high-performance composite PCMs. The research findings indicate significant potential for HDF/PEG in practical applications such as solar energy utilization, thermal management, and thermal energy storage, contributing to the advancement of clean and renewable energy technologies.
DOI:
10.1007/s11708-025-0991-7