Hierarchical CuCo2O4 nanowire@NiCo2O4 nanosheet core/shell arrays for high-performance supercapacitors

Abstract

Ternary metal oxides have attracted extensive attention for supercapacitor applications due to their enhanced performance compared to their binary counterparts. In this work, 3D CuCo₂O₄@NiCo₂O₄ core/shell nanostructures have been synthesized via a two-step method on nickel foam followed by a post annealing process. Morphological characterizations show that the porous CuCo₂O₄ nanowires are well covered by NiCo₂O₄ nanosheets. The hybrid electrode is used as a binder-free electrode, showing a high specific capacitance of 2029 F g⁻¹ (while the areal capacitance is 2.59 F cm⁻²) at the current density of 10 mA cm⁻², higher than the CuCo₂O₄ electrode. After 4500 cycles, the specific capacitance remains 1548 F g⁻¹, ∼80% of the original capacitance. In particular, the hybrid electrode exhibits great rate capability, the hybrid electrode retains 1551 F g⁻¹ as the current density increases to 30 mA cm⁻², which can be ascribed to the excellent electron transport properties of core/shell CuCo₂O₄@NiCo₂O₄ structures.