Hierarchical NiCo2O4/MnO2 core-shell nanosheets arrays for flexible asymmetric supercapacitor

Rational construction of binder-free electrode is regarded as a promising way to improve the electrochemical performance of supercapacitor. Herein, we synthesize a hierarchical NiCo2O4/MnO2 core-shell nanosheets arrays by two-step cathodic electrodeposition method. The optimized NiCo2O4/MnO2 electrode prepared by the electrodeposition potential of - 1.8 V for 240 s shows a large specific capacitance of 3.81 F cm(-2) at 2 mA cm(-2). The enhanced electrochemical performance is attributed to the unique core-shell structure of NiCo2O4/MnO2 nanosheets arrays with appropriate interspaces between nanosheets that can offer more active sites and accelerate ion/electron transfer rate. Besides, the NiCo2O4/MnO2//AC flexible asymmetric supercapacitor achieves a high energy density of 2.55 mWh cm(-3) with good stability (86.1% of initial capacitance can remain after 10000 cycles), indicating the perfect energy storage features.