Self-stretchable, helical carbon nanotube yarn supercapacitors with stable performance under extreme deformation conditions

•Self-stretchable fiber-shaped supercapacitors based on helical.•CNT yarns or CNT/PPy composite yarns without using external substrates are fabricated.•which can work stably under many extreme deformation conditions such as super-elongation.•arbitrary shape change, and high frequency stretching.

Stretchable fiber-shaped supercapacitors have been fabricated by attaching active materials to elastic polymeric substrates. Here, we report a substrate-free, self-stretchable carbon nanotube (CNT) yarn supercapacitor utilizing the helical loop structure incorporated into the CNT yarns. Our helical CNT yarn supercapacitors can work stably under many extreme deformation conditions such as super-elongation (tensile strain up to 150%), arbitrary shape change (entangling), and high frequency stretching (up to 10 Hz over 10000 cycles). By designing and manufacturing particular yarn structures as described here, fiber-shaped supercapacitors with unprecedented properties and high performance could be developed, which have potential applications in portable, wearable, and body-integrated energy storage devices.

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