Improvement of nickel-cobalt-based supercapacitors energy storage performance by modification of elements.

Hybrid supercapacitors have the advantages of fast charging and discharging and long service life, which are an efficient and practical energy storage device. Therefore, the design of hybrid supercapacitors is the focus of current research. In this paper, the silver modified spinel NiCo2S4 nanorods (Ag2S-NiCo2S4/CF) are synthesized by an efficient and economical method, which has excellent electrochemical performance. The Ag2S-NiCo2S4/CF shows a high specific capacity of 179.7 mAh g-1 at current density of 1 A g-1, and excellent rate capability (capacitance retention of ~87% at 20 A g-1). The corresponding Ag2S-NiCo2S4/CF//AC/CF hybrid supercapacitor is assembled by Ag2S-NiCo2S4/CF as the positive electrode, which can provide an energy density of 35.978 Wh kg-1 at a high-power density of 800 W kg-1 and has significant cyclic stability (~80% of the initial capacitor after ~9600 cycles). Therefore, Ag2S-NiCo2S4/CF material is a promising electrode material that can be applied to hybrid supercapacitors.