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 Ni 3 S 2 (denoted as Co-Ni 3 S 2 ) 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 Ni 3 S 2 electrode. Moreover, the energy storage device assembled with the Co-Ni 3 S 2 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).