Facile synthesis of hierarchical core-shell heterostructured NiCo2O4@MnMoO4 nanosheet hybrid arrays on nickel foam for high-performance asymmetric supercapacitors

Hierarchical core-shell heterostructured NiCo2O4@MnMoO4 nanosheet hybrid arrays were successfully synthesized on nickel foam via a facile two-step hydrothermal reaction followed by a calcination process. The highly porous hierarchical core-shell heterostructure was fabricated by preforming a NiCo2O4 nanosheet core as a substrate and then guiding the ultrathin MnMoO4 nanosheet shell onto its surface. The growth thickness of ultrathin MnMoO4 nanosheets was controlled by adjusting the hydrothermal reaction time. The optimized coreshell heterostructured NiCo2O4@MnMoO4 electrode exhibited a specific capacity of 1205.75 C g-1 at a current density of 1 mA cm-2 in 2 M KOH solution and displayed outstanding cycling stability with a capacity retention rate of 100.49% after 5000 charge-discharge cycles at a current density of 30 mA cm-2. An asymmetric supercapacitor (ASC) device was assembled using the optimal NiCo2O4@MnMoO4 nanosheet hybrid arrays as the positive electrode and activated carbon (AC) as the negative electrode which achieved a maximum energy density of 39.04 W h kg- 1 at a power density of 156.86 W kg- 1 and retained 34.12 W h kg- 1 even at the high power density of 1568.74 W kg- 1. In addition, the ASC device presented an excellent cycling performance, maintaining 95.00% retention of its initial specific capacitance after 10,000 cycles at a current density of 20 mA cm-2, demonstrating its promising potential in energy storage.

Automated summary

Hierarchical core-shell heterostructured NiCo2O4@MnMoO4 nanosheet hybrid arrays were synthesized and exhibited outstanding electrochemical performance.