Abstract
In this work, the Co-Ni basic carbonate nanowires were in-situ grown on carbon nanotube (CNT) network through a facile chemical bath deposition method, which could be further converted into active hydroxide via cyclic voltammetry strategy. A series of carbonate nanowire/nanotube with different Co/Ni ratio revealed the different growth status of the nanowires on CNT network. The nanostructures of the as-synthesized samples were examined via powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) techniques. The Co/Ni ratio of the carbonate largely affected the size of the nanowires, that the low Co/Ni ratio was beneficial for thin nanowire formation and the nanowires loading on CNT network. Subsequently, the electrochemical performance of the Co-Ni basic hydroxides was studied in a three-electrode test system. The nanowires with low Co/Ni ratio 1/2 can form nanowire array on individual CNTs, which exhibited better electrochemical capacitive performance than the composite network with high Co/Ni ratio nanowires after electrochemical activation. The addition of Co enhanced the rate performance of the hydroxide/CNT, especially improved the long cycle stability largely compared to the rate performance of pure Ni converted hydroxide/CNT composite film reported by our previous research. This result is valuable for the design of inorganic electrochemical active composites based on conductive networks for energy conversion/storage applications.
Highlights
In recent years, effective energy storage and utilization have attracted much attention for the fast development of electronic devices and the increasing environmental problems (Liu et al, 2010; Zhou et al, 2019a) Among various energy storage strategies, electrochemical energy storage usually plays a key role in the individual electrical and electronic devices with the requirement of stable power supplement (Mathis et al, 2019; Wang et al, 2020) As an important part of electrochemical energy storage device, the electrode should match various requirements for effective energy storage andCo-Ni Carbon Network With High-Capacitance power supplement, such as high conductivity, high power and energy density, long cycle stability, facile synthesis, high utilization, low cost and environmental friendliness
In different electrochemical energy storage devices, the metallic compounds with high energy densities and capacities but poor conductivity are used as the electrodes (Nguyen and Montemor 2017; Li et al, 2019) To increase the power density and active the batteries materials, the electrodes with high conductivity are necessary (Chen et al, 2019; Kim and Moon 2020) In commercialized electrodes, the simple mixing of electrochemical active materials and the conductive fillers is a common method
The conductive additive unavoidably sacrifices overall energy storage capacity and the mixture with low ratio of conductive fillers could not ensure the stable conductive network in the electrodes, which limits the performance of the electrodes (Farzaneh and Hadi, 2019) To enhance the construction of the conductive network in the electrodes, direct growth of electrochemical active materials on the as-prepared conductive network is an effective approach. (Hosseini and Shahrokhian 2018)
Summary
Effective energy storage and utilization have attracted much attention for the fast development of electronic devices and the increasing environmental problems (Liu et al, 2010; Zhou et al, 2019a) Among various energy storage strategies, electrochemical energy storage usually plays a key role in the individual electrical and electronic devices with the requirement of stable power supplement (Mathis et al, 2019; Wang et al, 2020) As an important part of electrochemical energy storage device, the electrode should match various requirements for effective energy storage and. The conductive additive unavoidably sacrifices overall energy storage capacity and the mixture with low ratio of conductive fillers could not ensure the stable conductive network in the electrodes, which limits the performance of the electrodes (Farzaneh and Hadi, 2019) To enhance the construction of the conductive network in the electrodes, direct growth of electrochemical active materials on the as-prepared conductive network is an effective approach. Compared to the rate performance of pure Ni converted hydroxide/CNT composite film reported by our previous research, the introduce of Co enhanced the rate performance of the hydroxide, and largely improved the long cycle stability. Electrochemical activation can largely increase the electrochemical capacitance of the composite films with low Co/Ni ratio, suggesting that the scalable, robust and conductive activated CNT composition may serve as a promising candidate for the electrodes of high-performance electrochemical energy storage devices
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