Interior design of three-dimensional CuO ordered architectures with enhanced performance for supercapacitors

Abstract

Oriented assembly of low-dimensional building blocks into their higher order three-dimensional (3D) multifunctional architectures is a fascinating technique to improve the electrochemical performance of random low-dimensional materials. Here, we have successfully realized two 3D CuO ordered nanostructures (CONs) assembled by 1D and 2D building blocks via a facile solvothermal method with mixed solutions of deionized water and ethylene glycol (EG). The synergistic effect of EG and n-butylamine on the crystal nucleation and growth process dominates the fabrication of various 3D architectures. Compared with disorganized 2D nanoflakes, 3D CONs exhibit higher specific surface areas, more convenient electron and ion mobility, and greater structural stability, which contribute to the rapid and reversible redox reaction in pseudocapacitors. Impressively, the electrochemical characteristics are greatly improved by 3D CON electrodes, showing high specific capacitance (541 and 585 F g⁻¹ at 1 A g⁻¹), good rate capability (retaining 81% and 79% at 20 A g⁻¹), and stable cycle life (85.3% and 86.8% capacitance retention after 8000 cycles). More importantly, the asymmetric supercapacitor based on 3D CONs expresses excellent cycling stability (85.3% capacitance retention after 10 000 cycles) and high energy density (31.47 W h kg⁻¹ at a power density of 892 W kg⁻¹). The design of the 3D porous ordered nanostructures would provide a novel and ideal approach for enhancing comprehensive performance of other electrode materials in energy conversion and storage fields.