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

ABSTRACT 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.