Boosting the performance of cobalt molybdate nanorods by introducing nanoflake-like cobalt boride to form a heterostructure for aqueous hybrid supercapacitors.

The CoMoO 4 /Co-B heterostructure was synthesized via the water bath deposition and liquid-phase reduction method and its electrochemical properties was investigated. Binary transition metal oxides have received extensive attention because of their multiple oxidation states. However, due to the inherent vices of poor electronic/ionic conductivities, their practical performance as supercapacitor material is limited. Herein, a cobalt molybdate/cobalt boride (CoMoO 4 /Co-B) composite is constructed with cobalt boride nanoflake-like as a conductive additive in CoMoO 4 nanorods using a facile water bath deposition process and liquid-phase reduction method. The effects of CoMoO 4 /Co-B mass ratios on its electrochemical performance are investigated. Remarkably, the CoMoO 4 /Co-B composite obtained at a mass ratio of 2:1 shows highly enhanced electrochemical performance relative to those obtained at other ratios and exhibits an optimum specific capacity of 436 F g−1 at 0.5 A g−1. This kind of composite could also display great rate capacity (294 F g−1 at 10 A g−1) and outstanding long cycle performance (90.5% capacitance retention over 10 000 cycles at 5 A g−1). Also, the asymmetric supercapacitor device is prepared by using CoMoO 4 /Co-B composite as the anode with the active carbon as the cathode. Such a device demonstrates an outstanding energy density of 23.18 Wh kg−1 and superior long-term stability with 100% initial specific capacity retained after 10,000 cycles. The superior electrochemical properties show that the CoMoO 4 /Co-B electrode material has tremendous potential in energy storage equipment applications. [ABSTRACT FROM AUTHOR]