Highly aligned and densified carbon nanotube films with superior thermal conductivity and mechanical strength

Flexible thermal conducting materials with the combination of excellent thermal conductivity and mechanical strength are highly desired for many practical applications, but meeting this strict requirement remains as a big challenge. Herein, facile preparation of highly aligned carbon nanotube (CNT) films is demonstrated, which involves the continuous production of a hollow cylindrical CNT assembly, followed by in-situ alignment of CNTs through optimizing the winding rate and a further stretching-pressing process. Benefiting from the resultant excellent CNT alignment and high density (1.59 ± 0.05 g cm−3), the CNT film simultaneously has a high thermal conductivity of 558.06–700.15 W m−1 K−1, electrical conductivity of 4870 ± 150 S cm−1, mechanical strength of 2.74–2.95 GPa, and Young's modulus of 55.2–58.9 GPa. The combination of such high thermal and mechanical properties is outstanding for carbon-based thermal conducting materials. Furthermore, the CNT material exhibits negligible structural and mechanical decay even after 500 cycles of bending test. Our study provides an effective strategy toward developing new thermal conducting materials for applications under harsh conditions.