Hierarchical three-dimensional FeCo2O4@MnO2 core-shell nanosheet arrays on nickel foam for high-performance supercapacitor

•First report hierarchical 3D FeCo2O4@MnO2 core-shell nanosheet arrays on Ni foam.•The Ni@FeCo2O4@MnO2 electrode possesses excellent electrochemical performance.•High specific capacity is attributed to the synergistic effect of FeCo2O4@MnO2 system.•3D Ni@FeCo2O4@MnO2 SC devices exhibit good cycling stability even after long cycle.

Developing supercapacitors with high energy density, good rate capability, and superior cycle life is crucial to the ever-increasing energy storage devices. However, how to design and develop a new type of faradaic electrode material with large surface area, low resistance, and stable microstructures is still a challenge work. Herein, we have successfully realized a high-energy and long-life supercapacitor by developing nickel foam-hierarchical three-dimensional iron cobaltate nanosheet arrays framework, and covering the surface with thin nanosheets of manganese dioxide (Ni@FeCo2O4@MnO2). The free-standing supercapacitor device based on this structure gives rise to a high energy density of 22.2 Whkg−1 at a power density of 978.3 Wkg−1, and ∼87.2% of the capacitance can be retained after 5000 cycles of charge-discharge. These performance features are excellent among those reported for iron cobaltate based supercapacitors, making it a promising candidate for high-performance electrochemical energy storage.