Formation and Electrochemical Assessment of Flexible Supercapacitor Yarns Directly Integrated into Woven Structures

Yarn-shaped energy-storage devices, including supercapacitor yarns and battery yarns, have been widely reported in literature, but their seamless integration into a base textile fabric (or substrate) using automatic weaving processes is yet to be fully demonstrated and explored. Here we present a set of woven fabrics formed using an automatic weaving machine. The fabrics were carefully customized to directly integrate a set of flexible supercapacitor yarns developed in our labs into different textile base (substrate) fabric structures. Two structures were formed: single- layer plain weave and double-layer plain weave designs with carefully selected structural parameters to protect the supercapacitor yarns during weaving and end use applications. The double-layer plain weave was formed with tubes strategically placed in the fabric to accommodate the supercapacitor yarns with thought to provide them with more protection than single-layer plain weave from stress during end use. Each electrode of the supercapacitor was formed by covering carbon fiber tow(s) with two coats of Polyvinyl alcohol (PVA) based gel electrolyte and a double wrap of PVA flat multifilament yarn between the two coats as electric insulator. The electrochemical integrity of the supercapacitor yarns was not negatively affected by the rigor of weaving whether woven in warp or weft direction and endured long exposure to extreme hot/humid and cold environments, accelerated distress, and surface abrasion. The double-layer plain weave structure allowed the supercapacitor yarns to sustain a longer duration of surface abrasion as compared to the single-layer plain weave structure. This work sheds light on existing myths of electronic textiles, where electronic components and textile yarns need to be integrated in an organic manner within textile structures for wearable textiles and other smart textile products.