Dip-coating construction of high-performance NiO micro-nanorod arrays on nickel foam for asymmetric supercapacitors

A straightforward dip-coating method was proposed for the direct construction of three-dimensional NiO micro-nanorod arrays on nickel foam. The morphology and crystal structure were characterized by scanning electron microscopy and X-ray diffraction, respectively, confirming the beneficial growth and favorable crystallinity of the fabricated micro-nanorods. Electrochemical measurements revealed that the NiO micro-nanorod arrays electrode delivered a high specific capacitance of 1400 F g −1 at a current density of 1 A g −1 in 2 M NaOH electrolyte. Furthermore, an asymmetric supercapacitor was assembled using the fabricated NiO as the positive electrode and activated carbon as the negative electrode. At a current density of 0.5 A g −1 , the device achieved a energy density of 114.74 Wh kg −1 , while a maximum power density of 14 kW kg −1 was attained at an energy density of 73.84 Wh kg −1 . Remarkably, the device exhibited outstanding cycling stability, maintaining 100% capacitance retention and 99.1% Coulombic efficiency after 5000 charge–discharge cycles. This work presented a simple, safe, and efficient strategy for fabricating NiO micro-nanorod arrays structure, offering a promising route toward high-performance electrochemical energy storage devices. Graphical abstract