Transition metal dichalcogenide nanostructured electrodes without calcination for aqueous asymmetric supercapacitors

Abstract

The controlled development of mixed phases of transition metal dichalcogenide (TMDC) electrodes with hierarchical nanostructures overcomes the limited contribution of pure TMDC compositions, which is desirable to achieve superior electrochemical performance. Herein, the flower-like NiMo3S4/NiS2 (NMS/NS) nanostructures with mixed-phase nature were grown on conductive carbon cloth (ie, NMS/NS@CC-210) at 210°C (24 h) by a hydrothermal method. Importantly, the uniform flower-like nanostructured NMS/NS@CC-210 electrode revealed battery-like performance with a superior specific capacitance of 1448 F g−1 (480 C g−1 at 1 A g−1) than the other NMS/NS@CC (180°C, 190°C, and 200°C) electrodes at different reaction temperatures as well as single counterparts of MoS2 (MS)@CC-210 and NiS2(NS)@CC-210 electrodes. The presence of plenty of lattice defects in NMS/NS@CC-210 electrode structure is favored to the exposure of several electrochemical active sites for rapid transportation of electron and electrolyte diffusion, resulting in better cycling retention (83%) behavior than the pure MoS2@CC (50%) and NiS2@CC (68%) electrodes after successive 5000 cycles. Using the optimized NMS/NS@CC-210 electrode, an asymmetric electrochemical capacitor was fabricated, and its electrochemical behavior was evaluated in a two-electrode system. The NMS/NS@CC-210//activated carbon (AC)@CC device delivered its superior energy and power densities of 43.8 W h kg−1 and 12 853 W kg−1, respectively. Finally, two flexible NMS/NS@CC-210//AC@CC devices with similar features were made and successfully powered the 3-V-based light-emitting diodes and display portable electronics for practical applications.