Fish scales inspired phase change composites with hierarchical porosity and enhanced thermal conductivity for passive thermal management

Abstract

Phase change composites (PCCs) suffer from short thermal management times and over-reliance on external coolers, which confine their applications in the fields of passive thermal management. Inspired by the overlapping gap structure of fish scales, scaly carbon-based aerogels composed of 25 wt%, 50 wt%, and 75 wt% expanded graphite (EG) sheets were prepared and then adhered by locust bean gum (LBG), respectively. The organic phase change material octadecylamine (ODA) was loaded into the cross-stack structure of the aerogel to fabricate PCCs. The results indicated that the macropore and mesopore connected aerogel had the characteristic of hierarchical porosity with higher pore areas of 8.840 m² g⁻¹. The PCCs not only exhibited high enthalpy of 236.1 kJ kg⁻¹ but also demonstrated high thermal conductivity of 3.015 W m⁻¹ K⁻¹. The simulation tests without coolers showed that the PCCs prevented the thermoelectric cooler (TEC) from overheating and increased the effective thermal management time by over 330% compared to the bare substrates of TEC. The reported PCCs would have potential for direct applications in the passive thermal management of TEC.