Synergistic nitrogen and endohedral MoCl₅ doping for ultrahigh-conductivity carbon nanotube fibers

Lightweight and highly conductive carbon nanotube fibers (CNTFs) are attractive for flexible electronics, yet their performance remains constrained by inefficient charge transport. Here we report a synergistic doping strategy that integrates in-plane nitrogen doping with endohedral molybdenum pentachloride (MoCl₅) incorporation to produce CNTFs with exceptional electrical properties and environmental durability. Nitrogen doping creates sidewall defect sites that promote MoCl₅ encapsulation, yielding a strong charge-transfer effect and markedly increased carrier density. The resulting fibers achieve a high specific electrical conductivity of 14166 S m² kg^-1 and a current carrying capacity of 1241 A mm^-2, surpassing copper by 115% and 28%, respectively. The CNTFs also exhibit high flexibility and environmental stability, retaining performance under thermal, mechanical, and solvent stresses. When woven into textiles, they deliver an electromagnetic shielding effectiveness of 92.7 dB (8.2-12.4 GHz). This work establishes a scalable doping approach for fabricating ultrahigh-conductivity CNTFs for advanced flexible electronics.