Core-shell NiCo2S4@MnMoO4 as an Advanced Electrode Material for High-performance Electrochemical Energy Storage

Hierarchical NiCo 2 S 4 @MnMoO 4 core-shell structure composites are first designed and fabricated through a three-step hydrothermal process. NiCo 2 S 4 microspheres consisting of nanotubes are utilized as ideal conductive scaffolds, whereas ultrathin MnMoO 4 nanosheets are controllably deposited. This particular structure is beneficial to the migration and diffusion of ions, meaning that the redox reactions of the active materials can be carried out quickly and completely. The NiCo 2 S 4 @MnMoO 4 hybrid electrode shows an ultrahigh specific capacitance of 1186.44 F g −1 at a current density of 1 A g −1 (3.6 F cm −2 at 3 mA cm −2 ). It exhibits good cycling stability with 90.1 % capacitance retention over 5000 cycles at 10 A g −1 . Moreover, an electrochemical energy-storage device is fabricated, where the as-prepared NiCo 2 S 4 @MnMoO 4 is employed as both the cathode and anode. The device achieves a high energy density of 47.8 Wh kg −1 at a power density of 699.9 W kg −1 , as well as excellent cycling stability (88.3 % capacitance retention over 5000 cycles at 10 A g −1 ). The outstanding performance demonstrates that the NiCo 2 S 4 @MnMoO 4 core−shell composite is a promising electrode material for electrochemical energy storage, which may inspire researchers to continue investigating heterostructured materials as energy-storage materials. Graphical Structure is key : A NiCo 2 S 4 @MnMoO 4 core-shell structure is first fabricated by using a three-step hydrothermal process. The composite exhibits improved performance compared to pure NiCo 2 S 4 , owing to the porous structure, rich faradic reaction, and synergistic effect. Moreover, an electrochemical energy-storage device with this material achieves a high energy density and excellent cycling stability in 3 M KOH.