One-Pot Synthesis of Mos2 Nanoflakes Wrapped 2d Zeolitic Imidazolate Framework-Derived Cobalt Sulfide Nanosheet Arrays for High-Performance Asymmetric Supercapacitors

Abstract

Transition metal sulfides (TMSs) have been extensively explored as Faradaic electrode materials of supercapacitors (SCs) because of their rich oxidation states for charge transfer. However, the drawbacks of sluggish electrochemical kinetics, poor electric conductivity and volume expansion result in unfavorable electrochemical properties. Herein, an effective two-stage varying-temperature sulfurization is presented to construct Co3S4@MoS2 nanosheet arrays from a zeolitic imidazolate framework (ZIF) template. The formation mechanism of the hierarchical heterostructure is studied through control experiments, which unveils the pre-formation of Co3S4 at low temperature has the crucial to the structure. Profiting from compositional and structural superiorities, the charge storage capability Co3S4@MoS2 far exceeds individual Co3S4 or MoS2. Furthermore, the asymmetric supercapacitor (ASC) consists of Co3S4@MoS2 and activated carbon (AC) achieves a large energy density of 55.4 W h kg-1 at the power density of 900 W kg-1 with good cycle life (87.8% capacitance retention after 10000 cycles). The strategy reported here provides a new route to constructing advanced TMSs-based heterostructure electrode materials for next generation energy storage and conversion devices.

Keywords: supercapacitors, zeolitic imidazolate framework, Co3S4, MoS2