Method to produce composite nio/c material

FIELD: power engineering.

SUBSTANCE: method to produce a composite NiO/C material containing 15-60% NiO and representing crystallites β-NiO evenly distributed on a carbon carrier surface with the average size of 2-5 nm, is based on production of NiO nanoparticles as a result of electrochemical oxidation and destruction of two nickel electrodes in solutions of alkaline metal hydroxides with concentration of 2 mole/l under action of AC current with frequency of 50 Hz at average value of current referred to a unit of electrode surface area making 0.3-1.5 A/cm2, with simultaneous deposition of produced nickel oxide nanoparticles onto the carbon carrier, subsequent filtration of the produced suspension, washing of composite by distilled water and its drying at 80°C for 1 hour.

EFFECT: invention makes it possible to increase quality of produced material due to absence of admixtures and to reduce costs for its production.

4 ex

 

The invention relates to the field of electrochemical energy, namely, the preparation of the active mass of the electrode with nano-NiO particles on a carbon carrier used in chemical current sources, in particular Nickel-metal hydride batteries, and supercapacitors.

A method of obtaining (US patent # US 2010/0055568 A1, publ. 04.03.2010) composite materials (nanocomposites nanocomposite used in lithium batteries and supercapacitors, which represents an oxide of the transition metal on a carbon carrier. The method of obtaining nanocomposites nanocomposite consisting of an oxide of the transition metal (e.g., Ni) and one-dimensional multi-walled carbon nanotubes used as a carbon carrier, includes a preliminary dissolution of the surfactant in distilled water and mixing it with an ultrasonic stirrer for 1 hour. In the resulting solution was successively added carbon nanotubes, stirring the resulting suspension for 3 hours, then add the chloride of the metal as a precursor (such as NiCl2) and urea and stirred for another 20 minutes. With constant stirring, increase the temperature to 100°C and maintain it for 7 hours. The resulting suspension is dried in a vacuum at a temperature of 100°C, followed by heat-treatment is processing at a temperature of 300°C.

The disadvantage of this method is the length of the process and large energy costs associated with the need to use vacuum and repeated heat treatment in the temperature range of 100-300°C.

A method of obtaining nanocomposite material (Ji Yeong Lee, Kui Liang, Kay Hyeok An, Her Young Lee. Nickel oxide/carbon nanotubes nanocomposite for electrochemical capacitance // Synthetic Metals, 2005, V.150, R-157)consisting of Nickel oxide and multiwall carbon nanotubes as the carbon carrier used in supercapacitors. The method comprises pre-heating of nanotubes in 68% (by weight) solution of HNO320 hours for their effective dispersion, washing and filtering. Next, the nanotubes are mixed in an ultrasonic stirrer for 3 hours in distilled water. In a suspension of nanotubes add tetrahydroxide of Nickel acetate [Ni(CH3COO)2*4H2O] to obtain a 0.2 M solution of Nickel acetate. Then there is added 0.5 M solution of ammonium hydroxide. The resultant slurry is centrifuged to separate the obtained nanocomposites nanocomposite consisting of a hydroxide of Nickel and nanotubes. Nanocomposite mixed with distilled water in the ratio 1:1. The electrodes are prepared by immersing a substrate of Nickel foam in the slurry nanocomposites nanocomposite. After drying in air p is obtained samples of the parts are annealed at 280-320°C for 1.5 hours.

The disadvantage of this method is the duration of the preparatory phase using concentrated nitric acid, and pollution resulting product extraneous ions.

As a prototype, consider the method of preparation of a composite material (U.S. patent US No. 2003/0235760 A1, publ. 25.12.2003), consisting of carbon and Nickel are used as the anode in lead acid batteries.

The considered method of obtaining compounds of carbon and Nickel includes the preparation of an aqueous dispersion of carbon (e.g., acetylene black) and then adding water-soluble salts of Nickel (for example, of Nickel nitrate). Next, in the obtained dispersion is added dropwise a solution of sodium hydroxide to secure the connection of Nickel on the surface of the carbon. The obtained solid particles separated from the solution, washed with distilled water and dried for 2 hours at a temperature of 120°C. Then the particles maintained at a temperature of 300°C. in the presence of air for 30 minutes to obtain a carbon material containing NiO.

The disadvantages of the prototype should include pollution resulting product nitrite-ions, and the method of introduction of the sodium hydroxide in the solution, whereby a uniform distribution of particles of NiO on the surface of the carbon nanotubes and the size of the Cree is tallitot is determined by the technological parameters of the process: concentration and rate of introduction of the sodium hydroxide solution, as well as the intensity of mixing of the suspension. A significant impact on the structure of the obtained NiO particles will have a changing (decreasing) with time, the concentration of the precursor of Nickel, such as Nickel nitrate.

The technical object of the present invention is to develop a method of producing composite NiO/C material containing crystallites of β-NiO 2-5 nm in size, allowing to improve the quality of the material due to the absence of impurities and reduce the cost of its receipt by reducing energy costs by reducing the time of the process and reducing the temperature of the heat treatment.

The production of composite NiO/C material containing nano-sized crystallites of β-NiO, provided the proposed method. The essence of the method consists in the electrochemical production of Nickel oxide in the oxidation and destruction of the Nickel electrodes under the action of a current of alternating polarity in suspension carbon carrier in a solution of a hydroxide of one of the alkali metals with simultaneous precipitation of the formed nanoparticles of Nickel oxide on a carbon carrier, followed by filtering, washing and drying the precipitate.

The electrochemical process is carried out under the action of alternating current with frequency of 50 Hz with an average amount of current, referred to the unit area on top of the spine electrodes, 0.3-1.5 a/cm2using two Nickel electrodes in solutions of hydroxides of alkali metals concentration of 2 mol/l, the solution temperature is 40-50°C, and the drying is performed at a temperature of 80°C for 1 hour.

The proposed method of obtaining composite NiO/C material is based on the phenomenon of electrochemical oxidation and destruction of Nickel electrodes in solutions of hydroxides of alkali metals under the action of a current of alternating polarity with the simultaneous precipitation of the formed nanoparticles of Nickel oxide on a carbon carrier.

The proposed method allows to obtain a composition that does not contain impurities NiO/C material with the size of the crystallites of β-NiO 2-5 nm.

The method is performed using two identical electrodes made of Nickel foil. As the carrier uses carbon media (Vulkan XC-72). In 2 mol/l solution of alkali metal hydroxide is introduced under stirring carbon media, and then immersed in a solution of parallel electrodes, the distance between them is about 2 cm per hour on the electrodes an alternating current frequency of 50 Hz with an average amount of current, referred to the unit area of the electrode surface is equal to 0.4 A/cm2. The temperature of the solution is in the range of 40-50°C. the Obtained su is pensio composite material is filtered, wash the precipitate with distilled water, dried at a temperature of 80°C for 1 hour.

Example 1.

Composite NiO/C material was manufactured in the following way. In the sodium hydroxide solution concentration of 2 mol/l with stirring, was introduced carbon media Vulkan XC-72, in the amount of 2.5 g/L. Then in the solution were immersed electrodes of Nickel foil. The electrodes were applied alternating current density of 0.3 A/cm2within 2 hours, the suspension is continuously stirred, the temperature was maintained within 40-42°C. the resulting suspension composite material was filtered, the precipitate washed with distilled water, dried at 80°C for 1 hour. The content of nanoparticles of β-NiO composite material was 25%. The size of the crystallites of β-NiO amounted to 1-3 nm.

Example 2.

The process is similar to that shown in example 1 and was characterized by the fact that the current density of 0.8 A/cm2current was applied for 1 hour. The temperature was maintained within 47-50°C. the Content of nanoparticles of β-NiO composite material was 35%. The size of the crystallites of β-NiO was 2-4 nm.

Example 3.

The process is similar to that shown in example 1 and was characterized by the fact that the process took place in a solution of potassium hydroxide concentration of 2 mol/l, the current density was 0.3 A/cm2current was applied for 2.5 hours,the temperature was maintained within 40-43°C. The content of nanoparticles of β-NiO composite material was 20%. The size of the crystallites of β-NiO was 3-5 nm.

Example 4.

The process is similar to that shown in example 3, and was distinguished by the fact that the current density was 0,8A/cm2current was applied for 3.5 hours. The temperature was maintained within 48-51°C. the Content of nanoparticles of β-NiO composite material was 60%. The size of the crystallites of β-NiO was 2-3 nm.

On the basis of the performed experiments it can be concluded that the inventive method enables the production of composite NiO/C material without impurities content of β-NiO from 15 to 60% and the size of crystalline β-NiO 1-5 nm.

A method of obtaining a composite NiO/C material including electrochemical receipt of Nickel oxide by oxidation and destruction of Nickel electrodes in the suspension of the carbon carrier in a solution of a hydroxide of one of the alkali metals with simultaneous precipitation of the formed nanoparticles of Nickel oxide on a carbon carrier, subsequent filtration, washing and drying the sludge, characterized in that the electrochemical receipt of Nickel oxide is realized under the action of alternating current with frequency of 50 Hz with an average amount of current, referred to the unit area of the electrode surface, 0.3-1.5 a/cm2using two Nickel electrodes in solutions of hydroxide is in the alkali metal concentration of 2 mol/l, while the solution temperature is 40-50°C, and drying is carried out at a temperature of 80°C for 1 h



 

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