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.