Fabrication of nickel sulfide/hierarchical porous carbon from refining waste for high-performance supercapacitor

Abstract

The increasingly solid waste with high toxicity and complex composition brought serious environmental and economic problems. Nickel sulfide/hierarchical porous carbon (Ni3S2/HPCs) have been successfully synthesized from the Ni3S2/coke solid waste as raw materials by a co-activation method. KOH was used as the activator and KCl was used as the template to modulate the pore structure, resulting in the high specific surface area of 2738 m2 g−1 and the improved distribution of Ni3S2. The trace amount of Ni3S2 provided a wide range of active sites for charge storage and transfer. The synergistic effect of pseudocapacitance and electric double layer enhanced the energy storage properties and stability of Ni3S2/HPCs. The optimized Ni3S2/HPC-3 exhibited high capacitance of 360 F g−1 at a current density of 1 A g−1, in 6 M KOH electrolyte and high cycle stability of 95.7 % after 10,000 cycles at 10 A g−1. The assembled symmetrical supercapacitor achieved a power density of 19.65 W h kg−1 at 450 W kg−1 in 1 M Na2SO4 electrolyte, outperforming most other carbon-based symmetrical supercapacitors. This work demonstrates the high-value utilization of refining solid waste to fabricate an electric double layer/pseudocapacitor composite material through a facile synthesis strategy, which also provides a new insight of resources recycling.