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

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).

Automated summary

In this study, a hierarchical Co modified Ni3S2 electrode was synthesized via a simple sulfuration reaction from NiCo-LDH, showing superior electrochemical performances. Compared to NiCo-LDH precursor and monometallic Ni3S2 electrode, the developed electrode exhibited much higher specific capacitance and great rate capability. Moreover, the assembled energy storage device with the Co-Ni3S2 electrode and activated carbon electrode demonstrated high energy density, power density, and outstanding electrochemical stability.