LAUSR

Abstract Herein, we synthesize a hybrid negative electrode (Fe3C@NC/rGO) by using the ammonium ferric citrate (AFC) as Fe-source, under melamine atmosphere, in-situ growing the core–shell architecture, in which the Fe3C particles are encapsulated into the N-doping carbon (NC) shell on the surface of reduced graphene oxide (rGO). Resulting from the dual effect of NC and rGO, the Fe3C@NC/rGO exhibits high specific capacitance of 1091.9F g−1 at 10 mV s−1 (70% capacitance retention when the scan rate increased to 100 mV s−1) and long-term stability (96% capacitance retention after 8000 cycles), which outperforms all Fe-based electrodes reported so far in aqueous electrolytes. The Fe3C@NC/rGO-5 as negative electrode is matched with CNT-Ni(OH)2 positive electrode to fabricate an aqueous asymmetric supercapacitor (ASC). Based on the larger potential difference between peak potentials of the negative and positive electrodes, the assembled ASC can deliver the energy density of 84.8 Wh kg−1 along with the power density of 840 W kg−1 (the maximum power density could reach up to 42 kW kg−1), and shows only 2.3% capacitance decay after 10,000 cycles. Two assembled ASCs in series can easily light 55 LEDs.