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• NiS Sodium lignosulfonate. • Activated carbon Composite electrode materials. • Cycle life Asymmetric supercapacitor. In this paper, NiS nanoparticles had been successfully loaded on activated carbon (AC) derived from sodium lignosulfonate via hexadecyl trimethyl ammonium bromide assisted hydrothermal method. Due to synergistic effects of AC and NiS nanoparticles, the conductivity of the NiS/AC electrode is significantly improved, and the composite electrode exhibits a high specific capacity (677 C/g at 0.5 A g−1) and excellent rate performance. Moreover, an asymmetric supercapacitor (ASC) device was assembled with the NiS/AC composite as positive electrode and the AC as negative electrode to evaluate the electrochemical performance of NiS/AC composites in practical applications. The ASC device achieves a maximum energy density of 45.6 Wh/kg at a power density of 509.5 W/kg, and excellent cycling stability with 92.6% of capacitance retention after 20,000 cycles. The electrochemical performance suggests that NiS/AC composites have great application prospect as electrode materials for supercapacitors. [ABSTRACT FROM AUTHOR]