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Phase change materials (PCMs) can be used for efficient thermal energy harvesting, which has great potential for cost-effective thermal management and energy storage. However, the low intrinsic thermal conductivity of polymeric PCMs is a bottleneck for fast and efficient heat harvesting. Simultaneously, it is also a challenge to achieve a high thermal conductivity for phase change nanocomposites at low filler loading. Although constructing a three-dimensional (3D) thermally conductive network within PCMs can address these problems, the anisotropy of the 3D framework usually leads to poor thermal conductivity in the direction perpendicular to the alignment of fillers. Inspired by the interlaced structure of spider webs in nature, this study reports a new strategy for fabricating highly thermally conductive phase change composites (sw-GS/PW) with a 3D spider web (sw)-like structured graphene skeleton (GS) by hydrothermal reaction, radial freeze-casting and vacuum impregnation in paraffin wax (PW). The results show that the sw-GS hardly affected the phase transformation behavior of PW at low loading. Especially, sw-GS/PW exhibits both high cross-plane and in-plane thermal conductivity enhancements of ~ 1260% and ~ 840%, respectively, at an ultra-low filler loading of 2.25 vol.%. The thermal infrared results also demonstrate that sw-GS/PW possessed promising applications in battery thermal management.

Heat dissipation becomes a critical problem because of the miniaturisation and the increase of power density in electronic devices and electric equipment, which calls for electrical insulating materials with high thermal management capability. Epoxy thermosets have been widely used as electrical insulating materials, but suffer from their low thermal conductivity. This study reviewed the research progress on the development of epoxy thermosets with high pristine thermal conductivity. First, the thermal conduction mechanism of polymers was briefly introduced. Second, the approaches used to enhance the thermal conductivity of epoxy thermosets were summarised, which mainly dealt with the formation of microscopically anisotropic but macroscopically isotropic structure in the epoxy thermosets. Third, the applications of high thermal conductivity epoxy thermoset resins were reviewed. Finally, the review provided the existing challenges and the future directions for the development of epoxy thermosets with high pristine thermal conductivity.

Thermal management has become a crucial problem for high-power-density equipment and devices. Phase change materials (PCMs) have great prospects in thermal management applications because of their large capacity of heat storage and isothermal behavior during phase transition. However, low intrinsic thermal conductivity, ease of leakage, and lack of flexibility severely limit their applications. Solving one of these problems often comes at the expense of other performance of the PCMs. In this work, we report core–sheath structured phase change nanocomposites (PCNs) with an aligned and interconnected boron nitride nanosheet network by combining coaxial electrospinning, electrostatic spraying, and hot-pressing. The advanced PCN films exhibit an ultrahigh thermal conductivity of 28.3 W m−1 K−1 at a low BNNS loading (i.e., 32 wt%), which thereby endows the PCNs with high enthalpy (> 101 J g−1), outstanding ductility (> 40%) and improved fire retardancy. Therefore, our core–sheath strategies successfully balance the trade-off between thermal conductivity, flexibility, and phase change enthalpy of PCMs. Further, the PCNs provide powerful cooling solutions on 5G base station chips and thermoelectric generators, displaying promising thermal management applications on high-power-density equipment and thermoelectric conversion devices.