Seed-induced NiCo2S4 nanosheets with integral ultrafine nanocrystals for efficient supercapacitors

A novel double-layer Ni-Co seeds-induced route is developed for preparing NiCo2S4 nanosheets consisting of ultrafine nanocrystals with uniformly distributed elements via anion exchange method on porous nickel foam. The as-prepared NiCo2S4 electrodes exhibit an ultra-high specific capacitance (2514 F g(-1) at a current density of 0.5 A g(-1)) thanks to the unique nanosheets with integral ultrafine nanocrystals. After 5000 charge/discharge cycles, the electrode can maintain 86.5% of the initial capacitance. In addition, NiCo2S4 nanosheets//AC asymmetric supercapacitors exhibit a relatively high energy density of 59.5 Wh kg(-1) at a power density of 400 W kg(-1), and reserve 87% after 5000 cycles at 5 A g(-1), indicating their enormous potential in supercapacitors.