A hollow graphene/conducting polymer composite fiber is created with high mechanical and electronic properties and used to fabricate novel fiber-shaped supercapacitors that display high energy densities and long life stability. The fiber supercapacitors can be woven into flexible powering textiles that are particularly promising for portable and wearable electronic devices.

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+ These authors contributed equally to this work. Abstract Recently, fiber-shaped yarn supercapacitors (YSCs) have attracted extensively attention due to their merits of small volume, high flexibility and potential to be woven in the textiles for future wearable electronics. PEDOT: PSS possesses properties of high-redox capacitance, high conductivity and high intrinsic flexibility, so PEDOT: PSS yarn electrodes are quite promising in the field of YSCs. However, to the best of our knowledge, twisted yarns based on wetspun PEDOT: PSS fibers for fiber-shaped YSCs have not been reported. Herein, we develop a new coagulation bath with CaCl 2 in aqueous solution for preparing meter-long PEDOT: PSS fibers. The PEDOT: PSS fibers with good mechanical properties can be easily woven, sewed, knotted and braided as the YSCs electrode. The PEDOT: PSS fiber-based YSCs show a high areal capacitance of 119 mF cm -2 and areal energy density of 4.13 µWh cm -2 .

Table of Content By a facile two-step dissolution-precipitation treatment, novel core-shell S quantum dots/PVK nanocomposites are synthesized.Fig. 5. (a) Nyquist plots of the electrode for the different SQD/PVK nanocomposites, pure PVK and pure sulfur cathode after five cycles from 200 kHz to 100 mHz at room temperature. (b) Rate capabilities of the sulfur electrode and SQD/PVK nanocomposites. Cycling performance of sulfur and SQD/PVK nanocomposites electrode at a rate of 0.2 C (c) and 0.5 C (d).Fig. 6. (a) Typical CV curves of the SQD/PVK-B electrode. (b) Galvanostatic charge/discharge profiles of the SQD/PVK-B electrode at 0.75 C (c) EIS of the SQD/PVK-B electrode at different cycles. (d) Cycling performance of the SQD/PVK-B electrode at a rate of 0.75C. SEM image of the SQD/PVK-B electrode:(e) the fresh electrode, (f) the electrode after 500 cycles at 0.75 C.

For the electrochemical capacitors or supercapacitors, pseudo-capacitors, via the fast surface reactions, are able to storage/harvest more electrical energy compared with electrochemical double layer capacitors (EDLCs) by the ion adsorption route. Combination of pseudocapacitive materials including oxides, nitrides and polymers, as well as the understanding charge storage mechanisms and the development of advanced nanostructures, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemcial capacitors closer to that of batteries. Electroactive polymeric cathodes with designed structures, via the electrospinning (without polymeric additives) and surfactantfree precipitation polymerization routes, were herein fabricated for the abovementioned goals. The as-prepared polymeric active materials showed an electrochemical capacitance of around 200 F g −1 , with a higher cut-off voltage up to 4.2 V and an energy density up to 370 Wh kg −1 and power density up to 34 kW kg −1 in an organic electrolyte system.

Hollow fiber electrodes based on graphene/conducting polymer are developed by J. Cheng, B. Wang, H. Peng, and co‐workers to fabricate novel and high‐performance fiber‐shaped supercapacitors. As described on page 3646, the hollow composite fiber supercapacitors have an ultra‐high specific capacitance of 304.5 mF cm−2 and an ultra‐high energy density of 27.1 μW h cm−2 at a power density of 66.5 μW cm−2. These mechanical and electrochemical properties make the fiber supercapacitors a promising material for next‐generation wearable electronics.

In situ-formed porous carbon nanofibers were synthesized by electrospinning with a volatile solvent additive into an ice water bath.