2D heterostructure comprised of Ni3S2/d-Ti3C2 supported on Ni foam as binder-free electrode for hybrid supercapacitor

摘要

2D materials and their composites are promising energy storage candidates. In this work, 2D horizontal heterostructure comprised of Ni3S2/delaminated-Ti3C2, denoted as Ni3S2/d-Ti3C2, supported on Ni foam is prepared by a two-step method and used as binder free electrode for hybrid supercapacitor. The as-obtained composites are characterized by X-ray diffraction analysis, scanning electron microscope, transmission electron microscope and X-ray photoelectron spectroscopy. The electrochemical properties of Ni3S2/d-Ti3C2 on Ni foam (denoted as Ni3S2/d-Ti3C2/NF) are studied using cyclic voltammetry, galvanostatic charge-discharge analysis and electrochemical impedance spectroscopy. It is found that the Ni3S2/d-Ti3C2/NF electrode exhibits superior capacitive performance with specific capacity of 2204 F g(-1) at a constant current density of 1 A g(-1). A hybrid supercapacitor is fabricated by using Ni3S2/d-Ti3C2/NF electrode as positive electrode, active carbon (AC) coated on Ni foam as negative electrode and KOH aqueous solution as electrolyte. The Ni3S2/d-Ti3C2/NF//AC hybrid supercapacitor exhibits a maximum energy density of 23.6Wh kg(-1) and a maximum power density of 4004.4 W kg(-1). The results supply new strategy for constructing MXene-based 2D horizontal heterostructure, and suggest that Ni3S2/d-Ti3C2/NF composite as a binder free electrode is an ideal candidate for supercapacitor applications. (C) 2019 Elsevier B.V. All rights reserved.