Nickel-doped cobalt molybdate nanorods with excellent cycle stability for aqueous asymmetric supercapacitor

Herein, nickel-doped cobalt molybdate (NixCo1-xMoO4, x = 0, 0.1, 0.3, 0.4, 0.5, 0.6) with nanorods structure are successfully prepared through a facile co-precipitation approach. The molar ratio of nickel and cobalt would affect the morphologies. The Ni0.5Co0.5MoO4 electrode exhibits satisfactory specific capacity and rate performance (325.9 C/g at 0.5 A/g, 260 C/g at 10 A/g). Moreover, the asymmetric supercapacitor (ASC) device is assembled using Ni0.5Co0.5MoO4 and carbon spheres as positive and negative electrodes, respectively. The ASC device possesses high energy density of 31.57 Wh/kg at the power density of 400 W/kg, and even maintains high energy density of 13.56 Wh/kg at the power density of 8000 W/kg. Meantime, the ASC device possesses excellent capacitance retention rate and coulomb efficiency after 5000 charge-discharge cycles. And a red light-emitted diode is illumed using two ASC devices in series.