Investigation of characteristics of double Ni–Co and ternary Ni–Co–Al layered hydroxides for supercapacitor application
Nickel hydroxides are widely used as the active material in supercapacitors. To improvise electrochemical activity, activators, namely Co and Al compounds, are introduced into the structure of nickel hydroxide. The most effective is the introduction of activators directly into the structure of nicke...
| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
PC Technology Center
2019-04-01
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| Series: | Eastern-European Journal of Enterprise Technologies |
| Subjects: | |
| Online Access: | http://journals.uran.ua/eejet/article/view/164792 |
| Summary: | Nickel hydroxides are widely used as the active material in supercapacitors. To improvise electrochemical activity, activators, namely Co and Al compounds, are introduced into the structure of nickel hydroxide. The most effective is the introduction of activators directly into the structure of nickel hydroxide. Characteristics of double Ni–Co (Ni:Co=8:1) and triple Ni–Co–Al (Ni:Co:Al=8:1:2) hydroxides, synthesized by single-stage reverse titration method were studied. Crystal structure of the samples was studied by means of X-ray diffraction analysis, thermogravimetry and differential scanning calorimetry, electrochemical characteristics were studied by means of cyclic voltammetry and galvanostatic charge-discharge cyclic in supercapacitor regime. Comparative analysis of characteristics of double Ni–Co and triple Ni–Co–Al hydroxide was conducted. By means of XRD analysis, thermogravimetry, and differential scanning calorimetry it was found that Ni–Co–Al is layered triple hydroxide with the structure of α-Ni(OH)2 with high crystallinity. Ni-Co hydroxide is double Ni–Co hydroxide with the crystal lattice of β-Ni(OH)2, in which part of Ni2+ is isostructurally substituted by Co2+, and low crystallinity. By means of cyclic voltammetry and galvanostatic charge-discharge cycling, high electrochemical activity of Ni–Co hydroxide was found. By means of cyclic voltammetry, an abnormal, α-like behavior of Ni–Co with β-Ni(OH)2 lattice was found. The electrochemical activity of triple Ni–Co–Al hydroxide was found to be significantly lower than that of double Ni–Co hydroxide (maximum specific capacities are 550.4 F/g and 741.5 F/g, respectively), despite the structure of pure layered double hydroxide and presence of two activators. A hypothesis was proposed on the poisoning of Ni–Co–Al LTH with free aluminum compounds during reverse titration synthesis |
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| ISSN: | 1729-3774 1729-4061 |