Aluminum/Graphene Thermal Interface Materials with Positive Temperature Dependence

Graphene is widely used in excellent thermal interface materials (TIMs), thanks to its remarkably high in-plane thermal conductivity (k(parallel to)). However, the poor through-plane thermal conductivity (k(perpendicular to)) limits its further application. Here, we developed a simple in situ growth method to prepare graphene-based thermal interface composites with positively temperature-dependent thermal conductivity, which loaded aluminum (Al) nanoparticles onto graphene nanoplatelets (GNPs). To evaluate the variations in thermal performance, we determined the thermal diffusivity and specific heat capacity of the composites using a laser-flash analyzer and a differential scanning calorimeter, respectively. The Al nanoparticles act as bridges between the nanoplatelets, enhancing the k(perpendicular to) of the 1.3-Al/GNPs composite to 11.70 W<middle dot>m(-1)<middle dot>K-1 at 25 degrees C. Even more remarkably, those nanoparticles led to a unique increase in k(perpendicular to) with temperature, reaching 20.93 W<middle dot>m(-1)<middle dot>K-1 at 100 degrees C. Additionally, we conducted an in-depth investigation of the thermal conductivity mechanism of the Al/GNPs composites. The exceptional heat transport property enabled the composites to exhibit a superior heat dissipation performance in simulated practical applications. This work provides valuable insights into utilizing graphene in composites with Al nanoparticles, which have special thermal conductivity properties, and offers a promising pathway to enhance the k(perpendicular to) of graphene-based TIMs.