Rationally designed Mn2O3/CuxO core–shell heterostructure generated on copper foam as binder-free electrode for flexible asymmetric supercapacitor

Inherent poor conductivity and agglomeration of CuxO phase limit its further development in supercapacitors. High theoretical capacitance of Mn2O3 and the construction of core–shell heterostructure may provide a new strategy to solve these problems. Herein, the unique core–shell heterostructure of Mn2O3 nanosheets attached to CuxO nanowires is formed on copper foam (CF). This electrode material is prepared via an in-situ oxidation reaction followed by the combination of calcination and hydrothermal method. The areal capacitance of the as-obtained Mn2O3/CuxO/CF electrode at hydrothermal time of 9 h is 1403.5 mF cm−2 (779.7F g−1) at current density of 2 mA cm−2 (1 A g−1), which is much greater than that of other electrodes. It also exhibits a good stability with 92.8% retention of initial capacitance after 10,000 cycles. Besides, the flexible asymmetric supercapacitor (FASC) device is assembled by Mn2O3/CuxO/CF-9 and activated carbon (AC) coated on nickel foam (NF) as respective positive and negative electrodes. It can deliver specific capacitance of 512.7 mF cm−2 at 2 mA cm−2, and reaches 120.2 μWh cm−2 at a power density of 1.3 mW cm−2. The outstanding electrochemical characteristics may be ascribed to the unique core–shell heterostructure, making it potential application in the field of flexible supercapacitors.