All-Carbon Hybrid Mobile Ion Capacitors Enabled by 3D Laser Scribed Graphene

Abstract

Hybrid mobile ion capacitors (HMIC) have been proposed as a way to incorporate the advantages of both batteries and supercapacitors into one system. Unfortunately, considering the much slower Li+ intercalation/deintercalation process, finding a suitable battery anode material with high rate performance is still a major challenge. Here, we report the fabrication of laser scribed nitrogen-doped graphene (NLSG) with 3D structure as binder-free, and conductive additive-free anode. This NLSG anode has high nitrogen and oxygen doping (8.6 at% and 6.3 at%) leading to the formation of conductive electrodes with expanded lattice spacing, providing more convenient pathways and reaction sites for Li+ ions. Hybrid Li-ion capacitors (HLIC) were assembled by combining the NLSG anodes with hierarchical porous carbon (PC) cathodes obtained by pyrolysis of Ethylenediaminetetraacetic (EDTA) tetrasodium salt. The NLSG//PC hybrid Li-ion capacitors show an energy density (including the total weight of two electrodes) of 186 Wh kg−1 at 200 W kg−1. Even when power density increased to the level of conventional supercapacitors (20 kW kg−1), an energy density of 76 Wh kg−1 can still be obtained. Further, the devices exhibit excellent cycle life, retaining 87.5% of the initial value after 5000 cycles. This study demonstrates that laser scribed graphene is a very promising electrode for mobile ion capacitors.