Flexible Thermoelectric Device Based on Poly(ether-b-amide12) and High-Purity Carbon Nanotubes Mixed Bilayer Heterogeneous Films

Abstract

Thermoelectric (TE) generators are an appealing, ecofriendly energy harvesting technology capable of converting temperature gradients into electricity. Carbon nanotube (CNT) filled organic composites typically offer the best potential for making cheaper TE materials. In this study, a block copolymer poly­(ether-b-amide12) (PEBA) with excellent flexibility and mechanical properties was used to fabricate TE materials via blending CNTs. After doping PEBA with lithium chloride (PEBA-Li+), two types (p-type and n-type) of CNT filled PEBA-Li+ (CNT-PEBA-Li+) TE composites were obtained via a simple one-step casting method. Here, the n-type CNT is prepared by diethylenetriamine doping treatment of the pristine CNT (p-type). The resultant TE materials exhibited a bilayer heterogeneous (BH) structure comprised of a thermally nonconductive layer and a conductive layer. The Seebeck coefficient (S) and electrical conductivity (σ) (under the application of temperature gradient 20 K) for the obtained p-type CNT-PEBA-Li+ bilayer heterogeneous film (BHF) are 36.88 μV/K and 456 S/m and for the n-type CNT-PEBA-Li+ BHF are −33.25 μV/K and 492 S/m, respectively. We constructed this novel TE device by integrating p- and n-type elements. The results showed that generated TE voltages for the module made of three TE couples were able to reach 120 mV for a temperature gradient of 60 K. The TE device construction was more efficient and simpler due to the BH structure, as only two BHF types were needed and no thermal insulating layer was necessary. In addition, our TE device is flexible throughout the entire structure. These novel flexible TE composites may benefit future organic TE materials research and promote the application of flexible and wearable power-conversion devices for next-generation power generators and waste-heat-recovery systems.

Highly Stretchable Carbon Nanotubes/Polymer Thermoelectric Fibers

“…Compared with inorganic TE materials, the low Seebeck coefficient limits the TE performance of PEDOT:PSS. In some studies, inorganic TE materials with a high Seebeck coefficient or high conductivity are mixed into PEDOT:PSS to improve the TE performance of the composite, but this leads to a decrease in flexibility and stretchability. ,− Carbon materials, including carbon nanotubes (CNTs) and graphene, are flexible and conductive due to the characteristic structure of the two-dimensional hexagonal lattice of carbon atoms. − The strong π–π interaction between CNTs (or graphene) and PEDOT:PSS can effectively improve the conductivity of the composite while maintaining its flexibility. ,− In addition to conductive polymers, graphene can also be solely mixed into the elastomer to prepare flexible TE materials. − The resistance of some graphene-based TE materials is generally sensitive to mechanical strain. Thus, they are more suitable for TE sensors rather than TE generators. , However, most current wearable TE materials are only flexible rather than intrinsically stretchable.…”

Advances in organic thermoelectric materials and devices for smart applications

“…Jang et al 54 also employed triblock copolymer to modulate the elastic properties of a ternary OTE material with a ZT value of 0.00126. In addition, OTE devices can be integrated with a free‐standing film 55 or an active matrix made of polymer insulators poly(dimethylsiloxane) (PDMS), poly(vinyl alcohol), paper, and fibers, 56–59 thereby confirming their applications in bendable and wearable attachment requirements.…”

Progress of hybrid nanocomposite materials for thermoelectric applications

“…Luo et al 145 reported the preparation of CNT and block copolymer poly(ether-b-amide12) (PEBA) blended TE films, which were utilized for fabricating a flexible TEG. Firstly, PEBA was doped with LiClO 4 to prepare a PEBA-Li + solution.…”