凯发

Graphene quantum dots (GQDs) were directly used as a novel but powerful nano-sized (almost 10nm) conductive additive in the activated carbon-based electrode material, to construct an effective conductive network for the improvement of the supercapacitors’ capacitive performance. Testing the electrochemical performance of the composite electrode for different amounts of graphene quantum dots and different composite ways, with 10wt% carbon black for comparison, to study the relationship between the electrode structure and the capacitive characteristics. It was found that the specific capacitance (SC) and rate performance were enhanced when GQDs at an appropriate weight ratio (1wt%) in the electrode material, comparied with 10wt% carbon black (named as Y); The electrochemical performance for the composite electrode prepared by liquid mixing (named as G) is better than that prepared by followed thermal treatment (named as HG). The SC value of G series is 105 F g-1 at a current density of 100 mA g-1 and it could retain 70 F g-1 at 1 A g-1. Its energy density reach 28 Wh kg-1. The unusual phenomenon was attributed to the following two reasons: (i) the nanoscale graphene conductive additive could bridge actived carbon particles more effectively via a “filling” conducting mode, with appropriate and less amount and (ii) it is beneficial to improve capacity for GQDs with abundant functional groups and its inherent properties. On the contrary, when GQDs were excess, the effective conducting network was weakened, leading to a lower capacitive performance. The work for the industrial development of graphene and its application in supercapacitors provides a new direction.