The effect of template residual content on supercapacitive characteristics of Ni(OH)2, obtained by template homogeneous precipitation

Кovalenko, Vadym; Kotok, Valerii

doi:10.15587/1729-4061.2019.181020

Cited by 3 publications

(6 citation statements)

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“…2) revealed the formation of aggregates of particles of increased size. Culminal C8465 as a template, most likely, in addition to the formation of a 3D matrix, interacts with the synthesized hydroxide and exhibits the properties of a binder, causing particle aggregation, especially at high concentrations, which is consistent with the data reported in [52,53]. The freshly made electrode shows very low capacities at a current density of 10 mA/cm 2 , 0.9 F/g, and 0.35 mA⋅h/g.…”

Section: Discussion Of the Study Of The Characteristics Of Nickel Hydroxide Obtained By Cold Template Homogeneous Precipitationsupporting

confidence: 85%

“…To synthesize the starting Ni(OH) 2 , we used the method of template homogeneous precipitation from a 1 M solution of nickel nitrate containing 1 M urea in the presence of a high molecular weight soluble template Culminal C8465 with a concentration of 0.5 wt %. In contrast to the method described in [53], the synthesis was carried out at room temperature (20-30 °С) for 6 months. After obtaining, the precipitate was filtered under vacuum, dried at 75 °С for a day, ground, soaked in distilled water (for 24 hours), filtered, and re-dried under the same conditions.…”

Section: Methods Of Obtaining the Main Sample Of Nickel Hydroxidementioning

confidence: 99%

“…However, it is promising to use another strategy -the use of a template as an internal binder at the stage of forming a pasted-type electrode. The possibility of implementing this strategy is shown in [53].…”

Section: °с the Electrochemical Characteristics Of The Sample Were Studied By Cyclic Voltammetry And Galvanostatic Charge-discharge Cyclimentioning

confidence: 99%

“…Both methods were carried out in a special electrochemical cell SEC-2 (USSR) using an electronic potentiostat-galvanostat Ellins R-8 (RF). For research, we made binder-free working electrodes (without the introduction of an external binder [52,53]). The composition of the active mass: nickel hydroxide (84 wt %), GAK-2 graphite (16 wt %).…”

Section: Study Of the Characteristics Of Nickel Hydroxide Samplesmentioning

confidence: 99%

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Synthesis of Ni(OH)2, suitable for supercapacitor application, by the cold template homogeneous precipitation method

Кovalenko

Kotok

2021

EEJET

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α-Ni(OH)2 obtained by template homogeneous precipitation exhibits high electrochemical activity in supercapacitors. The main disadvantage is the high energy consumption for maintaining a high temperature during synthesis. To reduce energy consumption, it is proposed to lower the synthesis temperature. In the study, α-Ni(OH)2 was obtained by the method of cold template homogeneous precipitation using Culminal C8465 (0.5 %) as a template for 6 months at t=20–35 °С. The electrochemical characteristics of the sample were studied by cyclic voltammetry and galvanostatic charge-discharge cycling of a pasted binder-free electrode made without introducing an external binder in the supercapacitor mode. It was determined that low-crystalline α-Ni(OH)2 was formed, consisting of agglomerates of spherical particles. Low specific characteristics of nickel hydroxide were revealed at the beginning of cycling due to blocking of the active surface. It was shown that the specific capacity of the sample increased with further cycling due to the breakdown of aggregates into smaller particles; specific capacities of 80 F/g and 38 mA⋅h/g were obtained. However, the lack of binding properties of the template residues was revealed, resulting in a decrease in specific characteristics. It was concluded that it was necessary to introduce an external binder. A previously undescribed effect of a significant increase in the specific capacity during drying of an alkali-impregnated electrode caused by the disintegration of particle agglomerates during alkali carbonization (the maximum capacity is 135 F/g and 69 mA⋅h/g) was revealed. It was concluded that using the revealed effect of any nickel hydroxide samples obtained by various methods of bulk template synthesis was promising

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Section: Discussion Of the Study Of The Characteristics Of Nickel Hydroxide Obtained By Cold Template Homogeneous Precipitationsupporting

confidence: 85%

Section: Methods Of Obtaining the Main Sample Of Nickel Hydroxidementioning

confidence: 99%

Section: °с the Electrochemical Characteristics Of The Sample Were Studied By Cyclic Voltammetry And Galvanostatic Charge-discharge Cyclimentioning

confidence: 99%

Section: Study Of the Characteristics Of Nickel Hydroxide Samplesmentioning

confidence: 99%

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Synthesis of Ni(OH)2, suitable for supercapacitor application, by the cold template homogeneous precipitation method

Кovalenko

Kotok

2021

EEJET

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“…They can be used as the basis of pigments [2]. Due to the high electrochemical activity, various forms of nickel hydroxide are used in chemical current sources (batteries [3] and supercapacitors [4,5]). Because the oxidized form (NiOOH) has a brown-black color, and the reduced form (Ni(OH) 2 ) is practically transparent, nickel hydroxide is used as an active substance in sensors [6] (similar to other electrochemical sensors [7]) and as electrochromic substance [8,9].…”

Section: Introductionmentioning

confidence: 99%

Definition of the role of polyvinyl alcohol during formation and in the structure of cathodic synthesized composite electrochromic nickel hydroxide layer: template or surfactant

Кovalenko

Kotok

Zima

et al. 2022

EEJET

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One of the promising applications of nickel hydroxide is electrochemical electrochromic devices. To significantly improve the characteristics, the role of polyvinyl alcohol (PVA) in the synthesis and structure of composite Ni(OH)2-PVA films was investigated by studying the effect of its concentration (30, 40, 50 g/l) and polymerization degree (17-99, 24-99, 30-99 types). Adhesion was investigated visually, and electrochemical and electrochromic properties – by cyclic voltammetry with simultaneous recording of optical characteristics. It was shown that at a concentration of 30 g/l, the film peeled off and had weak electrochemical and electrochromic properties. The presence of two cathodic peaks (E=500–510 mV and E=560 mV) on the cyclic voltammetry showed the presence of nickel hydroxide in the PVA matrix and nickel hydroxide with adsorbed PVA. This indicates the dual role of PVA as a surfactant and as a template. At low concentrations, the role of PVA as a surfactant prevailed. Increasing the concentration led to an increase in the film characteristics by strengthening the role of PVA as a template: at 50 g/l, the film did not peel off and has good electrochemical and electrochromic characteristics. It is shown that at a low degree of polymerization, PVA (17-99 type) mainly played the role of a surfactant but was also a template. The film cracked and had mediocre characteristics. The use of medium polymerization PVA (24-99 type) gave a film with high adhesion, electrochemical and electrochromic characteristics. It is shown that in this case, PVA performed the function of a template, there was only one cathodic peak on the voltammogram at E=500–510 mV. It was found that the use of PVA with a high degree of polymerization (30-99 type) led to a significant deterioration of the characteristics, including complete peeling of the film. This is probably due to the loss of PVA in the film

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Nickel Hydroxides: Requirements, Targeted Construction and Choice of Characteristics and Industrially Applicable Synthesis for Targeted Use in Electrochemical Devices

Kovalenko,

Kotok

2024

ChemistrySelect

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Nickel hydroxides (monohydroxides of several modifications and layered double hydroxides, based on nickel hydroxide) have high electrochemical, electrochromic, and electrocatalytic properties that allow them to be effectively used as an active substance in alkaline batteries, hybrid supercapacitors, electrochemical sensors, for electrocatalytic oxidation of organic substances and as an electrochromic device. Each application has its specific requirements for nickel hydroxides which must be defined. For an effective application, it is necessary to carry out a targeted construction of structure and composition, and selection of characteristics of nickel hydroxides and to develop targeted methods and conditions for nickel hydroxide synthesis. The structure, properties, and methods of preparation for use in various fields of nickel hydroxide application have been considered from the targeted ternary points of view: requirements definition, types and characteristics selection, and applying the synthesis method in industry. The 3‐level hierarchical complex of mechanisms for the formation of nickel hydroxides has been described. Also, the contribution of Ukrainian scientists to research in the field of nickel hydroxides is considered.

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The effect of template residual content on supercapacitive characteristics of Ni(OH)2, obtained by template homogeneous precipitation

Cited by 3 publications

References 50 publications

Synthesis of Ni(OH)2, suitable for supercapacitor application, by the cold template homogeneous precipitation method

Synthesis of Ni(OH)2, suitable for supercapacitor application, by the cold template homogeneous precipitation method

Definition of the role of polyvinyl alcohol during formation and in the structure of cathodic synthesized composite electrochromic nickel hydroxide layer: template or surfactant

Nickel Hydroxides: Requirements, Targeted Construction and Choice of Characteristics and Industrially Applicable Synthesis for Targeted Use in Electrochemical Devices

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