Gallium‐Based Liquid Metal and Its Composites: From Fundamental Properties Toward Thermal Management Applications

ABSTRACT Gallium‐based liquid metals (LMs) and their composites have emerged as a highly adaptable materials platform for thermal management across multiple length scales, ranging from submicron interfaces to system‐level heat exchangers. This review provides a mechanism‐oriented perspective that explicitly correlates LM chemistry and liquid‐state structure with transport behavior, interfacial phenomena, and application‐specific performance. We first elucidate the distinctive bonding characteristics and short‐range order of Ga and Ga–In/Sn eutectic systems, and clarify how electrical and thermal transport, rheology, surface tension, oxidation, corrosion, and supercooling collectively govern their macroscopic thermal performance and reliability. On this basis, we systematically examine three representative application classes: (i) liquid‐metal‐based thermal interface materials, where interfacial metallization, filler‐assisted percolation, and polymer–LM architectures enable synergistic optimization of thermal resistance and mechanical compliance; (ii) liquid metal phase‐change materials for transient thermal buffering, with emphasis on latent heat utilization, supercooling suppression, and encapsulation strategies; and (iii) liquid metal heat‐transfer fluids and hybrid fluids for high‐heat‐flux convection, highlighting transport enhancement, material compatibility, and long‐term stability. Finally, we identify key opportunities and challenges for liquid‐metal thermal technologies, underscoring that performance breakthroughs critically rely on the co‐design of material chemistry, interfacial structure, and processing pathways.