A scalable strategy toward compliant tandem yarn-shaped supercapacitors with high voltage output

Abstract

Yarn-shaped supercapacitors (YSSCs) based on aqueous electrolyte exhibit a relatively low voltage output due to the low decomposition voltage of water (∼1.23 V). Applying organic-based electrolyte or connecting YSSCs in series with metal-wire involves issues such as safety, air stability, contact resistance and so on. Herein, these issues are addressed by designing tandem YSSCs (T-YSSCs) where several YSSCs are interconnected in series on a single poly(tetrafluoroethylene) (PTFE) filament using a simple dip-coating method. The resultant T-YSSCs display a high voltage density of 72 V m⁻¹, robust areal specific capacitance of 475.6 mF cm⁻², high electrochemical stability (95.2% retention after 10 000 cycles) and a tensile strength of 125.4 MPa. Moreover, they show negligible contact resistance compared to that of metal wires interconnected ones, because of the diminished built-in Schottky barrier between interconnected electrodes. An energy storage fabric (ESF) with adjustable voltage and current demonstrates good potential for on-body practical applications because it is well adapted to be worn on human body to power an electronic watch, a pedometer and so on.