One-step synthesis of nickel cobalt sulfide nanostructure for high-performance supercapacitor

Bimetallic sulfides are widely used in supercapacitor electrode materials. However, the sample preparation is usually complicated, and the followed performance is not very desirable generally. In this work, we report a one-step solvothermal method to synthesize Ni–Co–SX nanostructure which stacked into a pine cone structure. Noticeably, the optimized Ni–Co–S4 exhibited a high specific capacitance of 2215 F g−1 at a current density of 0.5 A g−1 and the capacitor retention rate is close to 90.16% after 10,000 cycles, which indicates that the cycle performance is superior. Moreover, Ni–Co–S4 can be used as the anode material coupled with cathodic activated carbon to assemble a high-performance asymmetric supercapacitor, revealing a high energy density of 36.6 Wh kg−1, a highest power density of 8.5 kW kg−1 with a capacitance retention of 85.06% after 10,000 cycles and an ability of lighting an LED for up to 15 min. The findings have implications to the design and control of the electrode materials for energy storage with high performance.