Recyclable and Binder‐Free EGaIn–Carbon Liquid Metal Composite: A Sustainable Approach for High‐Performance Stretchable Electronics, Thermal‐Interfacing and EMI‐Shielding

ABSTRACT Eutectic Gallium–Indium (EGaIn) liquid metal (LM) is a promising material for stretchable and printed electronics. Conventional LM composites use metallic powders and elastomeric binders to enable coating and printing, but rely on scarce, expensive metals, require sintering, exhibit reduced conductivity, and are difficult to recycle due to strong binding among components. A room temperature, sinter‐free, and binder‐free printable EGaIn–Carbon Black (CB) composite is introduced to address these limitations. The composite avoids intermetallic formation, enhancing recyclability. Although phase separation typically hinders stability, a tailored carbon activation process enables uniform dispersion. Incorporating only 1.5 wt.% CB imparts high viscosity (120 Pa s at 10 s −1 , 25°C), shear‐thinning behavior, and excellent printability without requiring binders. The composite achieves ∼60% of bulk EGaIn conductivity, while dynamic conductive bridge reformation enables mechanical stretchability and strain‐resilient performance. It also exhibits high thermal conductivity and strong electromagnetic interference (EMI) shielding (∼35 dB in the X‐band), which increases to ∼70 dB under 100% strain due to network densification. As thermal interface materials, the composite reduces device temperature from ∼80°C to ∼32°C within 20 min—outperforming commercial silicone pastes—owing to its high thermal conductivity, surface conformity, and stable interfacial contact.