Waste eggshell derived porous skeleton with dual functional CNT synergistically enhance the thermal property of PCMs for thermal management.

Latent heat storage technology has been demonstrated an efficient approach to address the energy supply-demand imbalance under the "dual carbon" target. To tackle the challenge of achieving a balanced, synergistic enhancement of thermal storage density and thermal conductivity during the development of shape-stabilized composite phase change materials (PCMs), this study cleverly employs the natural waste eggshell to derive a porous skeleton material-hydrothermal eggshell (HES) for encapsulating organic polyethylene glycol (PEG) PCMs. For the first time, the capacity of PEG/HES composite PCMs in thermal management for electronic devices has been investigated. Moreover, this work breaks through the limitations of nanoparticles as "blending-type" materials by introducing "encapsulate + heat transfer" dual-functional nanoparticles-carbon nanotubes (CNTs) into HES. This structure (HES@CNT) forms a "bridge" similar to the layout of human capillaries, enabling a simultaneous enhancement of both thermal storage density and thermal conductivity. The experimental results indicate that the thermal conductivity of PEG/HES composite PCM attains 1.308 W/(m·K), which is one order of magnitude higher than that of pure PEG. Furthermore, compared to the sample without CNTs, the PEG/HES@CNT composite PCM exhibits a 3.7-fold increase in latent heat of melting, while both crystallinity and thermal storage capacity exceed 80 %. Additionally, its thermal conductivity is further enhanced by 40 %, reaching 1.690 W/(m·K). Moreover, applying both PEG/HES and PEG/HES@CNT composite PCMs to electronic components could help lower the peak surface temperature and delay the time required to reach it, thereby helping to reduce thermal-mechanical cycle fatigue in practical electronic devices use and ensuring stable operation.