Hierarchical design of Ni3S2@Co9S8 nanotubes for supercapacitors with long cycle-life and high energy density

•Hierarchical NiS@CoS nanotubes are designed with high supercapacitor performance.•NiS@CoS nanotubes exhibit high specific capacitance of 9.79 F cm−2 at 2 mA cm−2.•The capacity of NiS@CoS nanotubes remains 80.8% after 10000 at 20 mA cm−2.•The NiS@CoS-12//AC HSC device shows ultrahigh energy density of 0.63 mWh cm−2.•Formation of nanotubes reduces the dangling bonds at edges for improved stability. Unique structured electrodes with abundant surface area is imperative for developing high-performance supercapacitors. Herein, hollow hierarchical Ni3S2 @Co9S8 (NiS@CoS) nanotubes are rationally designed by a one-pot strategy, which demonstrate a substantial high active area. Accordingly, NiS@CoS nanotubes have exhibited promising electrochemical energy storage characteristics with high areal specific capacitance (9.79 F cm−2 at 2 mA cm−2) and excellent cycling stability (80.8% retention after 10000 at 20 mA cm−2). Furthermore, the hybrid supercapacitor (HSC) is designed with the NiS@CoS and active carbon (AC) as positive and negative electrodes, respectively. Remarkably, the HSC achieves ultrahigh energy density of 0.63 mWh cm−2 at a power density of 1.66 mW cm−2 (and 0.37 mWh cm−2 at 21.76 mW cm−2). This work offers a simple and effective approach to fabricate low-cost transition metal sulfides with great prospects in practical energy storage applications.