Synthesis of transition metal cation decorated nickel molybdate nanoarrays on nickel foam and their applications in high-performance battery-supercapacitor hybrid devices

Abstract

Molybdenum-based metal oxides have attracted enormous attention because of their high specific capacity, but they still cannot meet current needs. To further enhance the electrochemical performance of the electrodes, we synthesized nanostructured zinc (Zn-)-decorated and cobalt (Co-)-decorated NiMoO4 arrays directly on nickel foams through a simple hydrothermal reaction followed by a calcination procedure. After being decorated with the transition metal cations, the capacities of the hybrid electrodes were marginally superior to the pristine NiMoO4. The optimized Co-decorated NiMoO4 electrode (CNM2) and Zn-decorated electrode (ZNM2) could deliver a high capacity of 1257.3 C g−1 and 969.2 C g−1, respectively, at a current density of 10 mA cm−2. The as-assembled CNM2//activated carbon battery-supercapacitor hybrid device yielded a high capacity of 87.4 F g−1 at a current density of 5 mA cm−2, maximum energy density of 31.1 W h kg−1 at the power density of 1249.9 W kg−1 and excellent stability with capacitance retention of 91.1% after 5000 continuous cycles at a current density of 10 mA cm−2. This work provides an alternative to fabricate other cation decorated transition metal oxide electrodes via a facile synthesis strategy and enable potential applications in the energy storage fields.