Effects of different directing agents on free-binder (Ni0.25Cu0.25Zn0.25Co0.25)MoO4 electrode for supercapacitor applications

The molybdates (MMoO4, M = Ni, Cu, Zn, and Co) were considered as high-performance electroactive materials for supercapacitor applications. Several strategies including ion doping and tuning the morphology were proposed to enhance the electrochemical performance of molybdates. In this work, a novel quaternary molybdate ((Ni0.25Cu0.25Zn0.25Co0.25)MoO4) was developed on the base of the similar crystal structure of molybdates. Furthermore, the morphology of ((Ni0.25Cu0.25Zn0.25Co0.25)MoO4 materials were adjusted by applying the various surfactants. The polyvinylpyrrolidone, cetyltrimethylammonium bromide, and sodium dodecyl sulfate surfactants led to the ingot-, sheet-, and semi-cuboid-like, respectively. The free-binder (Ni0.25Cu0.25Zn0.25Co0.25)MoO4 electrode with sheet-like morphology showed the specific capacitance as high as 1460 Fg−1 at a current density of 1 Ag−1 and excellent rate capability of 92 % by applying the current density up to 5 Ag−1. The sheet-like (Ni0.25Cu0.25Zn0.25Co0.25)MoO4//activated carbon asymmetric capacitor exhibited energy density of 63.1 Wh kg−1 at power density of 2900 W kg−1.