Continuous carbon nanotube fiber with an extremely high average specific strength of 4.1 N·tex⁻¹

Carbon nanotube fibers (CNTFs), which hold a transformative potential across fields from aerospace to wearable electronics, have been reported as superstrong fibers, while the fabrication of continuous fibers with excellent strength remains a challenge. Herein, we proposed a mixed carbon-source strategy that engineered carbon nanotube (CNT) aerogels with optimally aligned and controlled-entanglement CNT bundles, ensuring structural uniformity and enabling densification into highly oriented architectures via chlorosulfonic acid-assisted stretching, thus yielding continuous high-performance CNTFs. These continuous CNTFs exhibited superior tensile strength (4.10 ± 0.17 N·tex⁻¹, exceeding T1100), modulus (268 ± 16 N·tex⁻¹, 1.4 times of T1100), thermal conductivity (400 W·m⁻¹·K⁻¹, over 30 times of T1100) and electrical conductivity (1480 S·m²·kg⁻¹), along with exceptional flexibility indicated by knot-strength retention exceeding 45%. Comprehensive multi-point assessments confirmed that this method yielded a remarkable uniformity in both structural and functional properties across kilometer-scale lengths. These findings highlight the crucial role of nanotube alignment and interfacial engineering in enabling the scalable industrial implementation of high-performance CNTFs.