High‐Energy‐Density Graphene Hybrid Flexible Fiber Supercapacitors

Abstract Graphene fiber‐based supercapacitors (GFSCs) as flexible energy‐storage devices have achieved much in the wearable electronics. However, the GFSCs still suffer insufficient energy density, and of which desirable balance between mechanical and electrochemical properties has not been realized. Herein, we developed AgI and conductive polymer assisted co‐enhancement strategy to prepare the high‐performance GFSCs with super‐high energy density, favorable mechanical properties, and superior electrochemical properties. The conductive binder polymer, poly(3,4‐ethylenedioxythiophene) (PEDOT) was introduced into the GO spinning solution to enhance RGO fiber strength, conductivity, and electrochemical performance by forming a strong interface with GO in the spinning solution. On the other hand, the synergistic effect of micro‐ and nano‐scale AgI grown on the fiber surface and aqueous gel electrolyte widen the potential window of the GFSC to 1.6 V, which is much higher than that of reported GFSCs, and resulting in a significantly increased energy density. At 0.1 A cm −3 , the volumetric capacitance and energy density of the fabricated GFSCs are as high as 166.6 F cm −3 and 29.65 mWh cm −3 , respectively. The high strength and flexibility of the hybrid fibers endowed the GFSCs with ∼100 % capacitance retention when bent to 180°. This work opens a new way to design and fabricate high‐performance GFSCs.