Tailoring the composition and structure of Ni3S2 by introduction of Co towards high efficiency energy storage device

[Display omitted] •Composition and structure of Ni3S2 is tailored via a simple sulfuration reaction.•Co modified Ni3S2 electrode with a hierarchical structure is synthesized.•The obtained electrode exhibits high specific capacitance (1826.4 F g−1 at 2 A g−1).•The assembled device exhibits superior energy density, power density and stability. Tailoring the composition and structure of transition metal compounds via a simple method is a crucial step in the pursuit of high-performance electrochemical energy storage materials. Herein, we design and synthesize a Co modified Ni3S2 (denoted as Co-Ni3S2) electrode with a hierarchical structure by a simple one step sulfuration reaction from NiCo-LDH. Benefiting from both the hierarchical structure and the bimetallic composition, the developed electrode exhibits excellent electrochemical performances including ultrahigh specific capacitance (1826.4 F g−1 at 2 A g−1) and great rate capability (about 53.9% at 20 A g−1), which are much higher than that of NiCo-LDH precursor and monometallic Ni3S2 electrode. Moreover, the energy storage device assembled with the Co-Ni3S2 electrode and the activated carbon (AC) electrode exhibits superior energy density of 59.1 Wh kg−1 and 24.7 Wh kg−1 while maintaining the ultrahigh powder density of 1275.5 W kg−1 and 9.8 kW kg−1, respectively. In addition, the device also displays an outstanding electrochemical stability (about 94.9% retention after 16,000 cycles).