N, S-codoped porous carbon nanosheets decorated with Fe3C nanoparticles as high-performance anode materials for lithium ion hybrid supercapacitors

The practical applications of carbon anode for lithium-ion batteries (LIBs) are largely obstructed by their moderate rate capability and cyclic stability. Herein, we report a N, S-codoped porous carbon nanosheet (NSC) decorated with Fe3C nanoparticles (Fe3C/NSC) by a one-pot pyrolysis process. The high surface area and abundant defects of NSC can not only promote electrons and ions transfer, but also induce high pseudocapacitive contribution. More importantly, the synergistic catalysis effect of Fe–Nx and Fe3C can catalyze the reversible conversion of some solid electrolyte interface (SEI) components to offer excess capacity during cycling. As expected, the Fe3C–NSC anode delivers a discharge capacity of 750 mAh·g−1 under a current density of 0.5 A·g−1 through 500 cycles and retains a discharge capacity of 366 mAh·g−1 at 4 A·g−1 after 1600 cycles, respectively. Most importantly, the lithium-ion capacitors based on Fe3C/NSC anode demonstrate a high energy density of 249.5 Wh·kg−1 at 560 W·kg−1.Graphical Abstract