▎ 摘　　要

Nickel cobalt sulfide nanoparticles embedded in holey defect graphene hydrogel ( HGH) that exhibit highly porous structures and uniform nickel cobalt sulfide nanoparticle sizes are successfully prepared by a facile solvothermal-hydrothermal method. As an electrode material for supercapacitors, the as-prepared NiCo2S4@HGH shows ultra-high specific capacitances of 1000 F g(-1) and 800 F g(-1) at 0.5 and 6 A g(-1), respectively, owing to the outstanding electrical conductivity of HGH and high specific capacitance of NiCo2S4. After 2100 charge/discharge cycles at a current density of 6 A g(-1), 96.6% of the specific capacitance was retained, signifying the superb durability of NiCo2S4@HGH. Moreover, remarkable specific capacitance ( 312.6 F g(-1)) and capacity retention ( 87% after 5000 cycles) at 6 A g(-1) were displayed by the symmetric solid-state supercapacitor fabricated by using NiCo2S4@HGH electrodes. These auspicious supercapacitor performances demonstrate that the as-developed solvothermal-hydrothermal approach can be widely used to prepare graphene-coupled binary metal sulfides for high-performance supercapacitor applications.