MOF-derived hierarchical core-shell hollow iron-cobalt sulfides nanoarrays on Ni foam with enhanced electrochemical properties for high energy density asymmetric supercapacitors

By Kai Le, Mengjiao Gao, Wei Liu, Jiurong Liu, Zhou Wang, Fenglong Wang, Vignesh Murugadoss, Shide Wu, T. Ding, Zhanhu Guo. Electrochimica Acta, 2019

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Abstract In this work, hierarchical core-shell hollow iron-cobalt sulfides nanoarrays supported on conductive nickel foam (Fe-Co-S/NF) were fabricated using metal-organic frameworks (MOFs) as the sacrificial templates. Delicately manipulating the etching/ion-exchange reaction between Co-MOF and FeSO4 and the subsequent solvothermal sulfurization led to the formation of hierarchical core-shell hollow nanostructure with FeCo2S4-nanosheets shell assembled on the Co3S4 hollow nanoarrays. Owing to the complex composition and unique structure, the obtained Fe-Co-S/NF possessed abundant electroactive sites, short charge/ion diffusion path, rich redox reactions and good structural robustness, contributing to the boosted electrochemical performance as supercapacitor electrodes. Consequently, the obtained Fe-Co-S/NF electrode exhibited a specific capacitance of 2695 F g−1 at 1 A g−1, a favorable rate capability with 69.8% capacitance retention at 10 A g−1 (much higher than that of CoS/NF electrode, i.e., 36.3%), and a retention of 84% over 1000 cycles. Moreover, an asymmetric supercapacitor was assembled by engaging Fe-Co-S/NF and reduced graphene oxide (rGO) as cathode and anode, respectively. The obtained device delivered a high energy density of 43.6 W h kg−1 at a power density of 770 W kg−1, while maintaining a capacity retention of 89.6% after 5000 cycles. The robust electrochemical properties indicate that the Fe-Co-S/NF can be used as promising electrode materials for high performance supercapacitors applications.

Subfields: Electrical and Electronic Engineering, Electronic, Optical and Magnetic Materials, Renewable Energy, Sustainability and the Environment

View Paper: https://www.semanticscholar.org/paper/083954a25c6cc398f3b3d9930b8e8bc166673b73