Transforming Commercial Regenerated Cellulose Yarns into Multifunctional Wearable Electronic Textiles
Textile-based electronics hold great promise as they can endow the wearable devices soft and comfortable characteristics. In this work, multifunctional conductive yarn is fabricated by coating commercial regenerated cellulose (lyocell) yarn with polypyrrole (PPy). The method is simple, low-cost, and large-scalable that endows the common lyocell yarn flame-retardant, good electrical heating property and excellent electrochemical performance. The PPy-coated lyocell yarn (PCLY) behaves as regular yarn and can be hand-knitted into full fabric. The PCLY fabric demonstrated a high conductivity, allowing its use as a wearable joule heater. The polypyrrole coating significantly improved the limiting oxygen index (LOI) of the lyocell yarn from 21.7 % to 40.2 %, endowing the yarn excellent flame-retardant property. PCLY was stitched into a fabric to form interdigitated electrodes and further assembled into flexible textile micro-supercapacitors. The resulting device with 10 interdigitated electrodes exhibited high areal specific capacitance of 663 mF cm−2 and energy density of 21.6 μWh cm−2 at 1 mA cm−2. Furthermore, six devices in series could power a blue light-emitting-diode (LED) of 3 V for more than 30 seconds. This facile fabrication provides novel and practical insights toward the wearable textile-based electronics.