A MnCo2 O4 @NiMoO4 Core-Shell Composite Supported on Nickel Foam as a Supercapacitor Electrode for Energy Storage.

A MnCo2 O4 @NiMoO4 composite was synthesized on nickel foam by a two-step method. The composite has a core-shell structure in which MnCo2 O4 nanoneedles are wrapped by NiMoO4 nanoflakes. The MnCo2 O4 @NiMoO4 /Ni foam is applied as a binder-free electrode for supercapacitors and it achieves a specific capacitance of up to 1718 F g-1 at a current density of 1 A g-1 , and 84 % capacitance retention after 6000 charge-discharge cycles. The capacitance of the MnCo2 O4 @NiMoO4 composite is much higher than MnCo2 O4 nanoneedles and NiMoO4 nanoflakes alone. Moreover, a hybrid supercapacitor is assembled by applying the MnCo2 O4 @NiMoO4 /Ni foam as the positive electrode, activated carbon/Ni foam as the negative electrode. The hybrid supercapacitor reaches an energy density of up to 42.3 W h kg-1 at a power density of 797 W kg-1 , a power density of 6256 W kg-1 at an energy density of 17.4 W h kg-1 , and 86 % capacitance retention after 2000 charge-discharge cycles. The results suggest that the rational design of electrode materials with such structure and composition is an effective strategy to improve electrochemical performance.