Freestanding MnO2 nanoflakes on carbon nanotube covered nickel foam as a 3D binder-free supercapacitor electrode with high performance

Designing and fabricating self-supported and binder-free MnO2 nanostructure electrode to overcome their low conductivity for supercapacitor application with high comprehensive electrochemical performance, such as high capacitance, excellent stability, and good rate capability, is still a tremendous challenge. In this paper, carbon nanotubes are uniform covered on nickel foam (denote as CNT/Ni) by a simple dip & dry method to form a 3D skeleton for MnO2 nanosheets deposition (denoted as MnO2-CNT/Ni). Results show the MnO2-CNT/Ni electrode exhibits a unique 3D porous interconnected network with a high specific capacitance of 402.5 F g− 1 at 1 A g− 1 and a favorable cycling performance that 83% capacitance retained after 5000 cycles at a current density of 2 A g− 1. Meanwhile, the MnO2-CNT/Ni//CNT/Ni asymmetric supercapacitor exhibits an excellent energy density of 25 Wh kg− 1 at a power density of 0.9 kW kg− 1 with 85.3% capacitance retention after 5000 cycles. Therefore, such a facile and manageable method to prepare MnO2 electrode with high supercapacitor performance is offering a promising future for practical applications.