An All‐Carbon Nano‐Welding Strategy for Carbon Nanotube Films

Abstract Macroscopic carbon nanotube (CNT) assemblies, such as large‐area films and continuous fibers, greatly facilitate their applications in many areas, serving as structural and functional materials. However, when CNT macroscopic assemblies break, traditional methods relying on polymer binders for stacking up and cold pressing result in weakly bonded physical interfaces, severely compromising mechanical stability and electrical reliability. To address this challenge, this study proposed a glassy carbon (GC) nano‐welding strategy, which combined ethanol‐assisted densification and in situ growth of GC nanolayers wrapping around CNTs and filling the porous film to construct a chemically bonded 3D interpenetrating structure, addressing the weak interfacial bonding between contacted films. This approach enhanced the electrical conductivity of the CNT films by 268% and increased the interfacial joint strength by 12.7 times, while also demonstrating exceptional electromagnetic interference shielding performance (66 dB in the X‐band), fast Joule heating response. Mechanistic analysis revealed that interfacial charge transfers synergized with the porous structure to enhance SE. The nano‐welding approach could be useful in CNT film repair and reconstruction for applications in flexible electronics and wearable devices.