Fully stretchable self-charging power unit with micro-supercapacitor and triboelectric nanogenerator based on oxidized single-walled carbon nanotube/polymer electrodes

Highlights: • Ag NPs embedded with Ox-SWCNTs for current collectors of fully stretchable FTENG and MSC. • Intrinsically stretchable Ox-SWCNT/PVA/H₃PO₄ electrode for fully stretchable MSCs. • Highly durable, fully stretchable self-charging power unit that integrates MSC and FTENG. • Simultaneous energy harvesting and storage functions of the FS-SCPU from repetitive human motion. A key requirement for wearable electronics is an adequate and sustainable power source. Accordingly, a self-powering unit that replaces rechargeable secondary batteries is a promising solution. However, to realize permanent, maintenance-free, and highly durable wearable electronics, stretchable self-powering units that can harvest and store energy should be developed. In this study, we developed a fully stretchable self-charging power unit that integrates a micro-supercapacitor and triboelectric nanogenerator using oxidized single-walled carbon nanotube/polymer electrodes. The fully stretchable micro-supercapacitor with oxidized single-walled carbon nanotube/polyvinylalcohol electrodes exhibited a double layer capacitance of 20 mF cm⁻² at 0.1 mA cm⁻² and improved mechanical flexibility and stretchability over 10,000 cycles of stretching tests. A stretchable, polydimethylsiloxane-based current collector employing silver nanoparticles embedded with oxidized single-walled carbon nanotubes enabled the fully stretchable, freestanding-triboelectric-layer based nanogenerators to produce a maximum instantaneous power density of 84.4 mW m⁻² under periodic and round-trip sliding of a Nylon fabric while stretching up to 40% without significant performance degradation. Furthermore, a micro-supercapacitor of fully stretchable self-charging power unit could be successfully charged by the nanogenerator from 0 to 2.2 V in 1200 s and powered commercial digital clock for approximately 10 s. These results demonstrate that stretchable polymer composites with oxidized single-walled carbon nanotubes are suitable electrodes and active materials for fully stretchable and self-powered wearable electronics.