High-performance positive electrode material of MXene/FeNi2S4 nanocomposite for flexible supercapacitor with large potential window

Abstract

Developing heterostructured nanomaterials with abundant active sites and excellent electronic conductivity is essential to enhance the electrochemical activity of supercapacitors. Herein, MXene/FeNi2S4 composites, as a high-performance electrode material for the flexible supercapacitor, were fabricated using a simple probe sonication method. The formation of a 3D architecture can create abundant electrochemical active sites, promoting the charge transfer as well as the redox reactions. Accordingly, a supercapacitor electrode based on MXene/FeNi2S4 exhibited excellent electrochemical performances, with a high specific capacitance of 673 F/g at 1 A/g. When MXene/FeNi2S4 was used as the electrode material of an asymmetric supercapacitor, the device showed an outstanding specific capacitance of 141 F/g at 1 A/g in a large potential window of 1.8 V. Up to 90 % of this high specific capacitance was retained after 2000 charge–discharge cycles. Furthermore, the device displayed high values of both energy density (63.37 Wh/kg) and power density (900.98 W/kg). The device also exhibited stable electrochemical performances under high flex at the bending angle of 135°. The exceptional electrochemical performances of MXene/FeNi2S4 highlight its great potential as an excellent electrode material for the next generation of flexible energy storage devices.