Engineering Vertically Aligned Boron Nitride Skeletons Bridged by Trace Graphene for High-Performance Thermal...

Efficient thermal management has become a pivotal bottleneck for the reliability of high-power density electronics, such as 5G communication and artificial intelligence (AI) systems. Traditional thermal interface materials (TIMs) consisting of randomly arranged graphene and other fillers usually fail to effectively transfer heat in the vertical (through-plane) direction and may exhibit poor mechanical properties. To address these limitations, we propose a synergistic "heteroassembly" strategy to construct a robust, vertically aligned aerogel skeleton. By employing tannic acid-assisted ball milling followed by unidirectional freeze-casting, modified hexagonal boron nitride (h-BN) is efficiently intercalated into graphene oxide (GO) interlayers. Subsequent high-temperature thermal reduction yields a highly crystalline TA-BN/rGO aerogel with a specialized architecture. In this design, the vertically aligned h-BN serves as the primary electrically insulating thermal conduit, while trace reduced graphene oxide (rGO) functions as an "interfacial solder" to bridge h-BN platelets and reinforce the structural network. The final composite TIMs, obtained via vacuum impregnation with silicone rubber, exhibit a remarkable synergy of properties. At a low filler loading of 5 wt %, the composite achieves a through-plane thermal conductivity of 1.45 W m^-1 K^-1, representing an 806% enhancement over pure silicone gel. Furthermore, the material demonstrates superior electrical insulation and mechanical compliance. This work provides a scalable and material-efficient route for developing next-generation TIMs that simultaneously satisfy the rigorous demands of thermal efficiency and operational safety in advanced electronics.