LAUSR

Abstract Nickel cobalt sulfides have been widely used as the battery-type electrode materials for asymmetric supercapacitors. However, it is still a challenge that obtains a unique structure to improve their electrochemical characteristics and practical applications. Hollow porous structures with hetero-interfaces are currently promising to endow electroactive materials with excellent properties, such as well-defined interior voids, low density, high pore volume, and surface permeability. Herein, hetero-structure NiCo2S4/Co9S8 hollow spheres were synthesized by using the carbon spheres as the sacrificial template via the solvothermal method and anion exchange process. When evaluated as a promising electrode for supercapacitors, the NiCo2S4/Co9S8 electrode exhibited an excellent specific capacitance of 2180 F g−1 at the current density of 1 A g−1, a high capacity retention that the specific capacitance retained 1400 F g−1 even at 20 A g−1, and a long stable cycling performance of retaining ∼85% after 10,000 cycles. In addition, the asymmetric supercapacitors based on these hollow hetero-spheres exhibited a high energy density of 96.5 W h kg−1 at a power density of 0.8 kW kg−1. The energy density can achieve 51.7 W h kg−1 even at a higher power density of 20 kW kg−1, indicating that the NiCo2S4/Co9S8 hollow spheres have superior practical applications for energy storage.