Facile synthesis of ultrathin manganese dioxide nanosheets arrays on nickel foam as advanced binder-free supercapacitor electrodes

• Ultrathin manganese oxides nanosheet-decorated Ni foam as binder-free electrodes.
• The novel architecture exhibited a high capacitance of 595.2 F g−1.
• Excellent cycling stability: 89% capacitance retention after 3000 cycles.
• The fabrication strategy: one-pot, additive-free and large-scale.
• An energy density of 25.8 Wh kg−1 and a maximum power density of 223.2 kW kg−1.

Ultrathin MnO2 nanosheets arrays on Ni foam have been fabricated by a facile hydrothermal approach and further investigated as the binder-free electrode for high-performance supercapacitors. This unique well-designed binder-free electrode exhibits a high specific capacitance (595.2 F g−1 at a current density of 0.5 A g−1), good rate capability (64.1% retention), and excellent cycling stability (89% capacitance retention after 3000 cycles). Moreover, an asymmetric supercapacitor is constructed using the as-prepared MnO2 nanosheets arrays as the positive electrode and activated microwave exfoliated graphite oxide (MEGO) as the negative electrode. The optimized asymmetric supercapacitor displays excellent electrochemical performance with an energy density of 25.8 Wh kg−1 and a maximum power density of 223.2 kW kg−1. These impressive performances suggest that the MnO2 nanosheet array is a promising electrode material for supercapacitors.

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