Hierarchical porous activated graphene nanosheets with an ultra-high potential as electrode material for symmetric supercapacitors

Activated graphene nanosheets (AGNs) are fabricated from graphene nanosheets (GNSs) by the facile KOH activation process. It displays that the obtained AGNs have a hierarchical porous structure, leading to the superhigh specific surface area of 2662 m2 g−1. The obtained AGNs electrode exhibited high specific capacitance (238 F g−1 at 1 A g−1) and remarkable rate performance (79.41% at 10 A g−1), exhibiting higher rate performance than reported carbon materials. Furthermore, the AGNs also show exceptional cycling capacity (99% after 20,000 cycles at 5 A g−1) in 1.0 M TEA BF4/AN electrolyte with an ultra-high potential range from 0 to 3.5 V. The symmetric supercapacitor displays a high energy density of 42.78 Wh kg−1 at a power density of 2071 W kg−1 and excellent cycle stability. The superior electrochemical performance can be attributed to the high specific surface area that has a larger contact area with the electrolyte, and the porous structure which provides a richer ion transport channel. [Display omitted] ●The AGNs with the hierarchical porous structure were fabricated via the KOH activation of GNSs.●The AGNs show a high specific capacitance of 238 F g−1 at 1 A g−1 at an ultra-high potential range from 0 to 3.5 V in 1.0 M TEA BF4/AN electrolyte.●The symmetric supercapacitor displays a high energy density of 42.78 Wh kg−1 at a power density of 2071 W kg−1 and excellent cycle stability.