Facile Fabrication of Cotton-Based Thermoelectric Yarns for the Construction of Textile Generator with High Performance in Human Heat Harvesting

Thermoelectric (TE) textiles which can harvest thermal energy from the human body, are highly desirable and vital to the charging of wearable electronics owing to their stable and long-term power output. The typical carbon nanotube (CNT) yarns or bismuth telluride (Bi 2 Te 3 ) based inorganic TE materials used hitherto limit the development of TE textiles, because of their high cost and rareness. In this work, scalable and high-TE performance carbon nanotube composite yarns (CNTYs) are developed using p- and n-type tuneable multi-wall CNTs and single-wall CNTs as TE materials and waterborne polyurethane (WPU) as the binder. The mechanical properties of the CNTYs are tuned and improved considerably by adding a small amount of WPU. Furthermore, TE yarns with p- and n-type segmented structures are prepared by treating CNTYs with poly(3, 4-ethylene dioxythiophene): polystyrene sulfonate solution and n-type dopant polyetherimide, respectively. Based on the prepared p- and n-type segmented TE yarns, a TE textile with 75 p–n pairs that achieve outstanding TE output is fabricated. The TE textile can generate a high power density of 95.74 μW m −2 with a voltage density of 3.76 V m −2 at a temperature difference of 32 K. It provides an output voltage of ~ 37 mV outdoors (~ 12 ℃) when worn on the arm and demonstrates potential application to electronic devices after amplification. The fabrication method used in this study is not only a low-cost, scalable for preparing high-performance TE yarns but also realizes the body heat harvesting and temperature sensing of yarn-based TE textiles. Graphical Abstract