Highly efficient and wearable thermoelectric composites based on carbon nanotube film/polyaniline

Polyaniline (PANI) was prepared by in-situ polymerization and compounded on the two-dimensional network structural multi-walled carbon nanotube film (CNTF). Compared with the CNT/PANI composites fabricated by using CNT powders or dispersions, the compact and continuous network structure of CNTF/PANI is beneficial to both the thermoelectric and mechanical properties of the composites. The resultant CNTF/PANI composites with PANI polymerization time of 5 h obtain an electrical conductivity of 1 338.4 S/cm and Seebeck coefficient of 63.3 μV/K at 360 K, which are 168.7% and 5.7% higher than those of the CNTF (498.1 S/cm and 59.9 μV/K at 360 K). Consequently, a maximum power factor of 536.8 μW·m⁻¹·K⁻² at 360 K is acquired, which is about 2 times higher than that of CNTF (181.7 μW·m⁻¹·K⁻² at 360 K). The electrical conductivity of the composites could maintain 93.3% after being bent for 500 times, indicating the excellent flexibility. The tensile strength, Young's Modulus and toughness of CNTF/PANI composites (232.3 MPa, 3.6 GPa and 20.1 MJ/m³, respectively) are 3.5, 2.6 and 2.1 times of those of the CNTF. The flexible, free-standing, lightweight and high-strength CNTF/PANI composites reveal the excellent thermoelectric performance, which are promising in the applications in wearable thermoelectric devices.