Highly deformable and electrically conductive fibres with multiple functionalities may be useful for diverse applications. Here we report on a supercoil structure (i.e. coiling of a coil) of fibres fabricated by inserting a giant twist into spandex-core fibres wrapped in a carbon nanotube sheath. The resulting supercoiled fibres show a highly ordered and compact structure along the fibre direction, which can sustain up to 1,500% elastic deformation. The supercoiled fibre exhibits an increase in resistance of 4.2% for stretching of 1,000% when overcoated by a passivation layer. Moreover, by incorporating pseudocapacitive-active materials, we demonstrate the existence of superelastic supercapacitors with high linear and areal capacitance values of 21.7 mF cm-1 and 92.1 mF cm-2, respectively, that can be reversibly stretched by 1,000% without significant capacitance loss. The supercoiled fibre can also function as an electrothermal artificial muscle, contracting 4.2% (percentage of loaded fibre length) when 0.45 V mm-1 is applied.

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Asymmetric supercapacitors are receiving much research interests due to their wide operating potential window and high energy density. In this study, we report the fabrication of asymmetrically configured yarn based supercapacitor by using liquid-state biscrolling technology. High loading amounts of reduced graphene oxide anode guest (90.1 wt%) and MnO 2 cathode guest (70 wt%) materials were successfully embedded into carbon nanotube yarn host electrodes. The resulting asymmetric yarn supercapacitor coated by gel based organic electrolyte (PVDF-HFP-TEA$BF 4 ) exhibited wider potential window (up to 3.5 V) and resulting high energy density (43 mW h cm À2). Moreover, the yarn electrodes were mechanically strong enough to be woven into commercial textiles. The textile supercapacitor exhibited stable electrochemical energy storage performances during dynamically applied deformations.There is an especially important need for weavable yarn-based supercapacitors that can be used in electronic textiles. Yarnbased batteries can provide high specic energy storage capabilities, but their typically low charge and discharge rates are a problem for rapidly storing the energy generated by energy harvesters operating at the frequencies of body motion, or delivering high electrical power when needed.Yarn or ber based supercapacitors have advantages over conventional three-or two-dimension (3D, 2D) energy storage devices for powering wearable electronics, which can include micron-scale diameters, light weight, exibility or stretchability, and weavability into textiles.1-7 However, the energy storage densities of supercapacitors are lower than for the best batteries. In order to achieve high energy storage density for yarn or ber based supercapacitors, previous research has been conducted in two directions: one is to increase the capacitance (C) of the device by introducing pseudocapacitive materials, while the other is to widen the voltage window (V) of electrochemical operation by using asymmetric electrodes. Since the stored electrical energy is given by E ¼ 1/2CV 2 , both strategies are important. Environmentally friendly, cost-effective, highly performing metal oxides (MnO 2 ) 8,9 or various conducting polymers (e.g., poly(3,4-ethylenedioxythiophene) (PEDOT), polyaniline (PANI), polypyrrole (PPy)) 2,10-14 have been extensively studied as pseudocapacitive additives to dramatically improve the charge storage capability of 1D supercapacitors. Asymmetrically congured 1D supercapacitors used active materials like graphene, carbon nanotubes (CNTs), and PPy for anode yarns and materials like MnO 2 , MoS 2 , Ni(OH) 2 , Co 3 O 4 for cathode yarns, resulting in voltage windows between 1.5 V and 1.8 V. 15-22In this study, we realized ber supercapacitors having both high specic capacitances and increased potential windows. The rst utilized strategy was to trap pseudocapacitive guest materials within vascular, high electrical conductivity networks of twist-spun CNT yarns, which maximized the weight percent of the guest without sig...

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Hybrid CNTs yarn muscle could be actuated with excellent contraction and stability at low voltage.