Fabrication of Binder-Free and High Energy Density Yarn Supercapacitor for Wearable Electronics

Abstract

Textile-based electronics systems are gaining considerable popularity nowadays and the area of wearable electronics technology is going to explode in the near future. Currently, the research on the flexible and wearable energy storage devices, to realize as power sources in wearable electronics, is on the boom. Herein, a flexible yarn-based supercapacitor (YSC) is fabricated utilizing TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> nanofibers and multiwalled carbon nanotube deposited on carbon yarn through the facile electrophoretic deposition technique for flexible/wearable energy storage application. The binder-free, mechanically strong, and compact deposition of the active materials on carbon yarn promotes the charge/ionic transport. The fabricated YSC device delivers a capacitance of 36.8 mF/cm at 0.1 mA/cm current rate. Moreover, the device shows 90% capacitance retention after 10 000 cycles proving excellent mechanical stability for energy storage. Furthermore, the YSC shows 95% retention after 2000 bending cycles at 0.5 mA/cm, suggesting good flexibility of the device. The YSC device shows a maximum energy density of 11.5 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> Wh/cm and power density of 368 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">μ</i> W/cm, which is better than many YSCs reported in the literature. Three YSCs are integrated into a wearable fabric and glow a red LED for more than 5 min as demonstrated in the video proving its practical application.