Ingenious preparation of N/NiOx co-doped hierarchical porous carbon nanosheets derived from chitosan nanofibers for high-performance supercapacitors.

It is still a key challenge to find suitable materials and methods to obtain super capacitors (SCs) with high specific capacitance due to the difficulty of balancing low theoretical capacity of conventional carbon materials and the poor ion transportability of transition metal oxide. In this work, N Ni dual-doped porous carbon nanosheets (NiOx-NCNSs) are prepared through a novel way using original N-doped chitosan nanofibers and nickel nitrate to form honeycomb layered structure constructed by 2D fiber network as precursors. NiOx-NCNS exhibits a high specific surface area of 1847.4 m2 g-1 with a rich N content of up to 5.16 wt% and shows a higher specific capacitance of 614.6 F g-1 at a current density of 1 A g-1 than that of carbon nanosheets of undoped Ni (NCNS) (427.5 F g-1). More specifically, the SC assembled using NiOx-NCNS electrodes achieves a high energy density of 20.3 W h kg-1 at a power density of 240.9 W kg-1, which is superior to most of the CNS-based SCs that have been reported. After 10 000 cycles, the symmetric SC retains approximately 85.61% of the initial capacitance. The strategy provided in this work probes the feasibility of high-performance SCs.