Liquid Metal‐Architected Thermal Management Materials: Void Engineering for Simultaneous High Thermal Conductivity and Flame Retardancy

Thermal management materials face fundamental challenges in achieving high thermal conductivity while maintaining flame retardancy, limiting their applications in high-performance electronics. Here, we demonstrate that liquid metal-architected void engineering in silicone composites addresses these challenges through systematic interfacial microstructural control. Mechanochemical encapsulation of aluminum nitride particles with eutectic gallium-indium creates multifunctional core-shell fillers that eliminate processing-induced voids by reducing flow activation energy 2.48-fold, enabling homogeneous filler distribution and continuous thermal network formation. This approach achieves exceptional thermal conductivities of 4.60 W m^-1 K^-1 (in-plane) and 5.27 W m^-1 K^-1 (out-of-plane) at only 50 vol.% loading, exhibiting 2.19- and 2.69-fold enhancements over pristine composites and exceeding performance typically achieved at ≥60 vol.% filler content. Cross-sectional analysis confirms complete void elimination, correlating directly with superior thermal transport and mechanical integrity. Simultaneously, this void engineering strategy enhances flame retardancy through dual mechanisms: eliminating internal voids that serve as oxygen diffusion pathways and promoting uniform protective char formation during combustion. Cone calorimetry reveals a 13.39% reduction in total heat release compared to pristine composites, confirming effective fire suppression. This systematic void engineering approach offers a practical pathway for developing thermal management materials that meet the advanced performance and safety requirements of high-power electronic systems.