Manganese-doped tungsten disulfide microcones as binder-free electrode for high performance asymmetric supercapacitor

Abstract

Manganese-doped tungstate sulfide (Mn-WS2) microcones were developed with varying levels of Mn, grown directly on electrically conductive Ni foam, and used as binder-free electrode material for supercapacitors. The experimental research indicates that Mn-WS2 microcones has significantly improved electrochemical activity and cyclic stability compared with pure WS2 due to additional ion diffusion channels. A strong synergy between the transitional metal ions in Mn-WS2 remarkably improved the redox activity, rate capability, and cycling stability. The Mn-WS2 microcones had a high specific capacitance of 107.79 mA h g−1 at 1 A g−1, a high rate capability of 75.18% at 20 A g−1, and 96.1% capacitance retention after 10,000 charge–discharge cycles. The effect of Mn ions on the electrochemical performance of WS2 microcones was also studied in detail. The enhanced electrochemical performance of the electrode can be attributed to the unique structural features of WS2 microcones arrays grown in Ni foam, which allow the surface of WS2 to be highly accessible to electrolyte ions. Furthermore, an all solid state asymmetric supercapacitor (ASCs) assembled with Mn-WS2 microcones as anode and GO/Fe3O4 cathode (Mn-WS2//PVA-KOH// GO/Fe3O4) delivered high specific energy of 70.65 W h kg−1 at 997.41 W kg−1. These results confirm that Mn-WS2 with outstanding electrochemical properties could be a promising electrode material for practical application in electrochemical energy storage field.