Three-dimensional nitrogen-doped graphene hydrogel-based flexible all-solid-state supercapacitors

In this paper, a three-dimensional nitrogen-doped graphene nano-gel electrolyte (3DNG-PDMA nano-gel) for the preparation of high-performance all-solid-state supercapacitors was studied. Our research shows that the gel electrolyte has a stable three-dimensional network structure and good ionic conductivity (0.0625 S cm −1 ), and the all-solid-state supercapacitors (SCs) prepared by this gel electrolyte present good electrochemical performance. The specific capacitance of supercapacitor is 187.5 F g −1 under the current density of 1 A g −1 . Even at the high power density of 5 kW kg −1 , the energy density of supercapacitor can still reach 38 Wh kg −1 . After 2500 cycles, the specific capacitance remains 84.1% of the initial value, indicating that the material has good cycle stability. Besides, the gel has high mechanical flexibility, the strain reaches 2409.4% under the stress of 1805.48 kPa, and it has excellent swelling performance with the swelling rate of 706% in 5 h. Graphic abstract