ABSTRACT
Design and fabrication of novel electrode materials with excellent specific capacitance and cycle stability are urgent for advanced energy storage devices, and the combinability of multiple modification methods is still insufficient. Herein, Ni2+, Zn2+ double-cation-substitution Co carbonate hydroxide (NiZnCo-CH) nanosheets arrays were established on 3D copper with controllable morphology (3DCu@NiZnCo-CH). The self-standing scalable dendritic copper offers a large surface area and promotes fast electron transport. The 3DCu@NiZnCo-CH electrode shows a markedly improved electrochemical performance with a high specific capacity of â¼1008 C g-1 at 1 A g-1 (3.2, 2.83, and 1.26 times larger than Co-CH, ZnCo-CH, and NiCo-CH, respectively) and outstanding rate capability (828.8 C g-1 at 20 A g-1) due to its compositional and structural advantages. Density functional theory (DFT) calculation results illustrate that cation doping adjusts the adsorption process and optimizes the charge transfer kinetics. Moreover, an aqueous hybrid supercapacitor based on 3DCu@NiZnCo-CH and rGO demonstrates a high energy density of 42.29 Wh kg-1 at a power density of 376.37 W kg-1, along with superior cycling performance (retained 86.7% of the initial specific capacitance after 10,000 cycles). Impressively, these optimized 3DCu@NiZnCo-CH//rGO devices with ionic liquid can be operated stably in a large potential range of 4 V with greatly enhanced energy density and power capability (110.12 Wh kg-1 at a power density of 71.69 W kg-1). These findings may shed some light on the rational design of transition-metal compounds with tunable architectures by multiple modification methods for efficient energy storage.
ABSTRACT
Growing electroactive materials directly on a three-dimensional conductive substrate can effectively reduce the "ineffective area" of the electrode during the electrochemical reaction, increase the utilization rate of the material, and thus increase the energy density of the device. Using the network structure of the three-dimensional conductive substrate to design electrode materials with unique microstructures can also improve the stability of the materials. In this work, we obtained different copper-based materials on the copper foam (CF) by in-situ growth method, and designed an independent three-dimensional layered CuO@NiCoFe-S (CuO@NCFS) core-shell nanostructure composite material. CuO@NCFS exhibits excellent electrochemical performance, reaching a specific capacitance of 4551 mF cm-2 at a current density of 1 mA cm-2 with good cycle stability (94.2% after 5000 cycles). In addition, the asymmetric supercapacitor (ASC) uses CuO@NCFS as the positive electrode and rGO as the negative electrode, which can provide an energy rate density of 4.5 mW cm-2 at a high energy density of 99.9 µWh cm-2. The findings provide some insight into rational design of electrode materials for high performance energy storage.
