Developing supercapacitors with simultaneous superior power and energy density for energy-storage devices remains a challenge. In this work, single-phase NiS 2 microflowers were synthesized through a hydrothermal process coupled with subsequent sulfidation. The obtained NiS 2 microflowers perfectly inherited the flowerlike structure of the precursor, which was composed of nanosheets with firmly integrated nanoparticles. With the benefit of the single-phase crystal structure, suppressed surface oxidation, relatively high apparent conductivity, and unique nano/microstructure, the NiS 2 microflowers presented outstanding electrochemical performance in the LiOH electrolyte. Specifically, the NiS 2 microflowers exhibited high specific capacities of 813 C g −1 at 1 A g −1 and 580 C g −1 at 20 A g −1 and retained 93% of its initial capacity after 10,000-time cycling test. Moreover, an optimized NiS 2 // activated carbon (AC) hybrid supercapacitor fabricated with NiS 2 microflowers as the positive electrode and AC as the negative electrode operated stably at a large voltage window of 1.8 V. It further delivered a considerable energy density of 39.8 W h kg −1 at 900 W kg −1 . Impressively, the intriguing nano/microstructure further endowed the almost unabated capacitance after continuous cycling of 10,000 times. This study will definitely promote the design and preparation of high-performance nickel-based sulfides for hybrid supercapacitors.

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