One-Step Synthesis of Nanostructured CoS2 Grown on Titanium Carbide MXene for High-Performance Asymmetrical Supercapacitors

MXene (2D titanium carbide) as the electrode material for supercapacitors has been studied extensively and deeply in recent years. In order to enhance the electrochemical performance of MXene, CoS2 nanoparticles grown on MXene surface are constructed by a simple one-step solvent thermal method. CoS2 nanoparticles play a crucial part in increasing the active sites of metal ions on the surface of MXene. In three-electrode system, the obtained MXene/CoS2 composite delivers high performance. Its specific capacitance can be up to 1320 F g(-1) at a current density of 1 A g(-1) and it shows remarkable cycle performance with 78.4% after 3000 cycles at 10 A g(-1). Moreover, the asymmetric supercapacitors (ASCs) with reduced graphene oxide as the negative electrode and MXene/CoS2 composite as the positive electrode exhibit a wide potential window of 1.6 V and high energy density (28.8 Wh kg(-1)) at a power density of 800 W kg(-1). After 5000 cycles, the ASCs maintain 98% of initial specific capacitance at 5 A g(-1). These results can effectively promote the application in the supercapacitor materials.