Weldable and flexible graphene ribbon@Ni fibers with ultrahigh length capacitance for all-solid-state supercapacitors

Carbon-based fiber supercapacitors hold great potential in portable electronics. However, those fiber-based electrodes often suffer from low length capacitance and poor rate performance due to low electrical conductivity and sluggish ion diffusion kinetics. And the poor weldability hinders the design of complex circuits. Herein, we report a simple strategy to prepare weldable and flexible graphene ribbon@Ni fiber (GR-Ni-5) with fast ion/ electron transfer capabilities for fiber-shaped supercapacitors via the immersion-drying process and followed by thermal treatment. As a result, the GR-Ni-5 exhibits an ultrahigh length capacitance of 73.8 mF.cm(-1) at 2 mV.s(-1), remarkable rate performance (26.8 mF.cm(-1), 200 mV.s(-1)), and ultrahigh capacitance retention of 80% with the length of the electrode from 1.0 to 10.0 cm. Moreover, the assembled all-solid-state symmetric supercapacitor using GR-Ni-5 fibers as the electrodes and polyvinyl alcohol (PVA)/KOH gel as electrolyte can deliver remarkable electrochemistry properties, as well as good flexibility, and remarkable weldability which are beneficial for miniaturization and application.