在线阅读

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Partic. vol. 45 pp. 66-73 (August 2019)
doi: 10.1016/j.partic.2018.07.008

Urchin-like NiCo2S4 structures synthesized through a one-step solvothermal process for high-performance supercapacitors

Yan Hua,b,1, Jie Zhanga,b,1, Di Wanga, Jiangbo Suna, Li Zhanga, Yanjie Liua, Shiqiu Gaoa, Yanbin Cuia,*

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ybcui@ipe.ac.cn

Highlights

    • Urchin-like NiCo2S4 was synthesized through a one-step solvothermal process. • PEG 200 was used as a solvent and shape-control agent. • A NiCo2S4//AC asymmetric supercapacitor was fabricated. • An energy density of 37.32 Wh/kg was obtained at a power density of 317.8 W/kg.

Abstract

Nickel cobalt sulfides (NiCo2S4) have attracted considerable attention as electrode materials for supercapacitors. Herein, a sea-urchin-like NiCo2S4 material was synthesized through a one-step solvothermal process. Polyethylene glycol (PEG) 200 and thiourea were used as a shape-control agent and sulfur source for in-situ sulfuration, respectively. The urchin-like NiCo2S4 was characterized by X-ray powder diffraction, scanning electron microscopy, Brunauer–Emmett–Teller surface area, and electrochemical measurements. The resulting NiCo2S4 with ion diffusion-favored structure demonstrated remarkable electrochemical characteristics for supercapacitor with a high specific capacitance (1334 F/g at 0.5 A/g) and superior rate capability (78.1% of the original capacity from 0.5 to 20 A/g) in 6 M KOH aqueous solution. Furthermore, an asymmetric supercapacitor was assembled using NiCo2S4 as a positive electrode and activated carbon (AC) as a negative electrode. A NiCo2S4//AC device exhibited a high energy density of 37.32 Wh/kg at a power density of 317.8 W/kg with capacity retention of 91.9% and up to 2000 charge/discharge cycles at 3 A/g. The results demonstrate that the sea-urchin-like NiCo2S4 has potential applications in supercapacitors.

Graphical abstract

Keywords

NiCo2S4; PEG; Asymmetric supercapacitor; Urchin-like structure; High specific capacitance