Abstract
Nickel hydroxide is widely used as the active material of supercapacitors. The most active are samples of Ni(OH)2 with (α+β) layered structure, synthesized in the slit diaphragm electrolyzer. Influence of carbonate anion on the structure and electrochemical properties of nickel hydroxide samples has been studied by means of sample synthesis in the slit-diaphragm electrolyzer with the use of the diaphragm and cation-exchange membrane as chamber separator. The experiment revealed that when the diaphragm is used, there is a filtration flow from the anodic chamber (alkali with carbonate) into the cathodic chamber. Thus, the samples synthesized with the diaphragm are formed in the presence of carbonates, while the samples synthesized with the cation-exchange membrane – in the absence of carbonates. Crystal structure of the samples was studied by means of X-ray diffraction analysis, electrochemical characteristics – by means of cyclic voltammetry and galvanostatic charge-discharge cycling in the accumulator regime. Comparative analysis of the samples synthesized in the presence or absence of carbonates has been conducted. By means of X-ray diffraction and cyclic voltammetry, the key role of carbonate ions in the formation of monophase layered (α+β) structure has been revealed. The absence of carbonate resulted in lower crystallinity, α-phase content, the formation of the bi-phase system, composed of the mixture of β-form and (α+β)-structure, at high current densities (12 and 15.7 A/dm2). The study of electrochemical characteristics revealed a decrease in specific capacity by 14.7–31.4 % for hydroxide samples formed in the absence of carbonate ions. The highest specific capacity was obtained for the samples synthesized in the SDE at i=10 A/dm2 with the diaphragm (in the presence of carbonates) and with the membrane (in the absence of carbonates), and are 216.8 and 185 mA·h/g respectively. To increase specific capacity, it is recommended to conduct synthesis in the SDE with the use of the diaphragm and introduce an additional quantity of sodium carbonate into the anolyte
Highlights
Various modifications of nickel hydroxide possess high electrochemical activity [1], which results in their wide application in various electrochemical devices.Ni(OH)2 and nickel-based double and ternary hydroxides are the main component for the active material of nickel oxide electrode in alkaline Ni-Cd, Ni–Fe and Ni–MeH accumulators [2, 3]
While in the paper [33] it is noted that carbonate ions possess greater stabilizing properties. All these studies were conducted for layered double hydroxides (LDH), crystal lattice of which requires the presence of intercalated ions in order to compensate for the excess of positive charge
The aim of the work is to study the influence of carbonate cation on the formation and properties of nickel hydroxide synthesized in the slit-diaphragm electrolyzer with the diaphragm and with the cation-exchange membrane
Summary
Various modifications of nickel hydroxide possess high electrochemical activity [1], which results in their wide application in various electrochemical devices. Nickel hydroxide is used as active material for Faradic electrode in asymmetric supercapacitors. For thin-layer supercapacitors, a film of nickel hydroxide can be formed on a conductive substrate [10]. Because thin film of Ni(OH) is practically transparent and NiOOH has dark-brown color, nickel hydroxide is used as electrochromic material [11, 12]. Nickel hydroxide possesses high electrocatalytic activity and is used for oxidation of various organic compounds [13, 14], and in sensors [15, 16]. Determining the influence of synthesis parameters on the properties of resulting hydroxide is a relevant problem
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Eastern-European Journal of Enterprise Technologies
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
