Nanolayer‐Encapsulated Stretchable Liquid‐Metal Sheets for Thermal Management

ABSTRACT Efficient thermal management in stretchable electronics demands materials that seamlessly integrate high thermal conductivity, mechanical flexibility, and reliable interface stability. This paper presents a stretchable, thermally conductive, biphasic, liquid‐metal sheet (LM sheet)—formed by dispersing copper particles in gallium‐based liquid metal—encapsulated between nanoscale styrene–butadiene–styrene elastomer layers. This trilayer architecture establishes continuous thermal‐conduction pathways while providing excellent electrical insulation and corrosion resistance. The LM sheet achieves impressive in‐plane and through‐plane thermal conductivities (40.4 and 16.7 W m −1 K −1 , respectively), with an elongation at break >200%. Notably, it retains 96% of its thermal conductivity even under 100% tensile strain. It adheres strongly to various substrates without adhesives, excellently spreading heat in flexible heaters and stretchable LED devices under both static and stretched conditions. This paper presents a compelling strategy for developing next‐generation thermal‐interface materials for deformable and skin‐integrated electronic systems.