RU191378U1 - SUPERCAPACITOR - Google Patents

Abstract

The utility model relates to electrical engineering, in particular to supercapacitors. The supercapacitor consists of a sealed protective housing, the first and second electrodes, electrically isolated from each other. One or both of the electrodes are also isolated from the housing. The free volume of the cell and the space between the electrodes is filled with electrolyte. Carbon-containing materials containing the C-14 isotope are deposited on the surface of the first electrode. It is possible to create a device for the accumulation of electric charge that does not require charging from an external source of electricity and increase the duration of the device without using an external charging energy source.

Description

The technical field to which the utility model relates.

The utility model relates to electrical engineering, is intended for the accumulation and storage of electrical energy, can be used for generation, conversion, storage and long-term storage of electrical energy, in particular, as microelectronic power sources and autonomous electronic devices.

Characterization of analogues of a utility model (prior art)

A device (battery) for the accumulation of electricity is known, which operates on the principle of a secondary source of electrical energy, where electrical energy is converted into chemical energy (when charged) and back when discharged when chemical energy is converted into electrical energy. The most common type of lead battery. It consists of a housing, inside of which are placed positive electrodes of lead dioxide and negative electrodes of sponge lead. The space between the electrodes is filled with an electrolyte from an aqueous solution of sulfuric acid. During the discharge, the active mass of both the positive and negative electrodes is converted to lead sulfate. When the battery is operating, a chemical process is implemented, which is called double sulfization [Khrustalev D.A. Batteries - M: Emerald, 2003.], [Kashtanov V.P., Titov V.V., Uskov A.F. etc. Lead starter batteries. Leadership .. - M.: Military Publishing House, 1983. - 148 s]. Charging stops when the electrolyte reaches its maximum density. For an aqueous solution with sulfuric acid, it is 1.28 g / cm3. By the end of the discharge, the density decreases to 1.08-1.10 g / cm3, after which charging is required again.

These devices are the most common storage of electrical energy, due to the simplicity, manufacturability of their manufacture and relatively low cost. The devices have a high energy density and allow for repeated charging and discharging of the battery.

The disadvantages of this device are the need for an external source of electricity for charging, a long charging time, limited power, a small number of charge-discharge cycles. As a rule, the resource of such devices does not exceed 10 years.

A device for the accumulation of electric charge, known as a capacitor [Maxwell J.C. A Treatise on Electricity and Magnetism. - Dover, 1873. - P. 266 ff. - ISBN 0-486-60637-6. ], [B.M. Yavorsky, A.A. Detlaf. Handbook of physics for engineers and university students. - M: "Science", 1968.].

The simplest capacitor consists of two metal plates separated by a dielectric layer, a material that does not conduct electric current. If you connect the capacitor plates to a source of electrical energy, then the charging current will flow and positive and negative charges will accumulate on the metal plates. As soon as the capacitor is charged, the current in the circuit becomes equal to zero. If the capacitor is disconnected from the energy source, the accumulated charge will remain. When a capacitor is connected to a resistor, the capacitor discharge current flows through it until it is completely discharged. This cycle of charging - discharging can be repeated several times.

The advantages of capacitors as electric charge storage devices are their simplicity of manufacture, relatively short charging time, higher capacity and a greater number of charging cycles — discharging before failure, than with batteries.

The disadvantages of this device are the need for an external source of electricity to charge the capacitor.

Known devices for the accumulation of electric charge, called supercapacitors or ionistors [Conway V.E. Electrochemical Supercapacitors. Scientific Fundamentals and Technological Applications. N.Y .: Kluwer Academic Plenum Publ., 1999.], [Appl. Phys. Lett., 2000, 77, p. 2421], [Pankratov D.V. et al. Flexible thin supercapacitor based on a composite of multi-walled carbon nanotubes and electrically conductive polyaniline // Modern Problems of Science and Education. - 2012. - No. 4.], [http://pubs.acs.org/doi/abs/10.1021/n18038579].

The supercapacitor in the basic design has two electrodes in the form of plates of conductive material, between which is an organic or inorganic electrolyte. To improve the electrical parameters of the supercapacitor, the plates are additionally coated with a porous material (most often activated carbon). According to the principle of operation, a supercapacitor combines two devices - a capacitor and a battery.

The energy is stored in a supercapacitor by two mechanisms:

- due to the capacity of the double electric layer, which is formed at the electrode-electrolyte interface. Capacity in this case is defined as

where ε is the relative permeability of the double layer medium, ε0 is the vacuum permeability, A is the specific area of the electrode, d is the effective thickness of the double electric layer.

- due to the pseudo-intensity due to the occurrence of reversible chemical reactions between the electrode and the electrolyte. In this case, the accumulation of electrons has a Faraday character, when electrons are formed as a result of an oxidative reaction and are transferred through the electrode – electrolyte interface. The theoretical pseudo-capacity of metal oxide can be calculated by the formula:

where n is the number of electrons released as a result of the oxidation reaction, F is the Faraday constant, M is the molar mass of metal oxide, V is the window of operating voltages.

Moreover, such hybrid supercapacitors can achieve higher capacitance and power densities, while maintaining good stability characteristics during cycling.

CNTs have both the capacity of a double electric layer and pseudocapacitance. Depending on the properties of CNTs and on the method of manufacturing and configuration of the electrode, the specific electric capacity of the supercapacitor can reach 350 F / g [Chongfu Zhou. // Carbon Nanotube Based Electrochemical Supercapacitors - 2006, School of Polymer, Textile and Fiber Engineering, Georgia Institute of Technology. - P-18]. To improve the capacitive characteristics of a supercapacitor, the so-called functionalization of CNTs is carried out, which consists in their special processing with the introduction of atoms, radicals and functional groups in the structure of CNTs. For example, the functionalization of CNTs by the COOH group leads to an increase in the specific electric capacitance of the capacitor from 0.25 to 91.25 F / g [Christopher M. Anton, Matthew N. Ervin // Carbon Nanotube Based Flexible Supercapacitors - Army Research Laboratory, 2011. - P 7]. The highest value of the specific capacitance of a supercapacitor with CNTs, achieved so far, is 396 F / g [http://scsiexplorer.com.ua/index.php/osnovnie-ponyatiya/1201-superkondensator.html], however, with the development of technologies this the characteristic is constantly increasing, and there are reports of reaching a value of 500 F / g [http://rusnanonet.ru/news/37452/].

Currently, the electrodes of most commercial supercapacitors are made from all kinds of carbon modifications (graphite, activated carbon, carbon nanotubes, graphene, composite carbon materials, etc.), which are affordable and inexpensive materials and have excellent anti-corrosion properties. At the same time, CNTs have higher electronic conductivity compared to activated carbon. Carbon-based supercapacitors have cyclic stability and long life, as neither on the surface nor in the volume of the material of the electrode during the charge / discharge chemical reactions occur, and the accumulation and storage of charge is due to the double electric layer.

Advantages of a supercapacitor with CNTs:

- Higher specific capacitance in comparison with capacitors, greater specific power than that of the battery.

- long life time, i.e. resistance to the number of charge-discharge cycles, which it can withstand up to 106 with virtually no decrease in capacity.

The main disadvantage of a supercapacitor, as for a battery, is the need for an external source of electricity to charge.

The well-known radioisotope source of electrical energy (Beta Cell), created in 1913 by the British physicist G. Moseley. It was a glass flask silvered from the inside, in the center of which radium salt was placed on an insulated electrode. Beta decay electrons created a potential difference between the silver layer of the glass sphere and the electrode with radium salt. The Moseley cell was charged to a high voltage, limited by the voltage of the gas breakdown, which could be increased by evacuating the flask.

A device is known [Patent RU 2113739 C1] for generating electricity from intra-atomic due to radioactive alpha or beta decay, containing two closed metal shells cooled by water or air (emitter and collector), located one in another with a gap with a vacuum of 10-5 - 10-6 mm Hg, in which the radioactive material is deposited on the emitter in the form of a metal layer with a thickness of 25-100 microns, facing the gap and collector. In the gap between the emitter and the collector, there is a control metal grid electrically connected to the secondary winding of the high voltage transformer, powered by an industrial AC network with a frequency of 50 Hz, and the emitter and collector are electrically connected to the primary high voltage winding of the second transformer, the secondary winding of which is connected to the energy consumer . The device works as a constantly recharged capacitor, the charging current of which is determined by the flow of particles from the emitter to the collector.

The disadvantages of the described device are the need to maintain a vacuum in the gap between the emitter and the collector, as well as the need for an external energy source that modulates the voltage on the grid with an amplitude sufficient to completely inhibit the particles of radioactive decay.

Prototype Characterization

A known construction of a supercapacitor (SC), in which the electrodes acting as plates in the simplest capacitor, are made of carbon nanotubes (CNTs) [Yu.M. Wolfkovich et al. Power electrochemical supercapacitor based on carbon nanotubes. // Electrochemical energy. 2008.V. 8, No. 2. - 106-110 p.]. The working electrode of the prototype is made by uniformly applying powder from nanotubes synthesized by the electric arc method onto a substrate of non-porous graphite. A solution of sulfuric acid with a concentration of 35 wt% (density 1.26 g / cm3) was used as an electrolyte. To improve the operating characteristics of CNTs, they were hydrophilized by exposure to an electrolyte with polarization at a potential of 1.1 V. The prototype has a wide range of working potentials (over 1.4 V), specific power of about 20 kW / kg and specific energy of ~ 1 Wh / kg

The disadvantage of the prototype, as with the previously described analogues, is the need for an external source of electricity to charge the supercapacitor.

Utility Model Disclosure

The supercapacitor includes a sealed protective case, the first (working) and second (auxiliary) electrodes made of silicon, molybdenum, niobium, tungsten, zirconium, or alloys based on them, or corrosion-resistant steel, placed inside the case. The electrodes are electrically isolated from each other by a separator, preventing the mechanical contact of the electrodes and the mixing of the cathode and anode electrolytes, one of which or both are also electrically isolated from the housing. An electrolyte that uses an acid solution, for example, H2SO4 or HNO3, alkali, for example, NaOH or KOH, or a salt solution, for example, KCl, NaCl, KNO3, Na2SO4 fills the free volume of the cell and the space between the electrodes. Carbon-containing materials are deposited on the surface of the first electrode in the form of an array of carbon nanotubes (CNTs), fullerenes, graphene, soot, graphite, or their mixtures containing the C-14 isotope. On the surface or inside CNTs, radionuclides N-3, nickel-63, Sr-90, Kg-85, At-241, Ac-227, Th-229 can be located.

The manufacture of a supercapacitor includes the following steps: preparation of the first (working) and second (auxiliary) electrodes, with the application of a surface layer of carbon-containing materials on the first electrode, for example, in the form of an array of carbon nanotubes (CNTs) of fullerenes, graphene, soot, graphite, or a mixture thereof containing the C-14 isotope or consisting of the natural C-12 isotope and impregnated with a chemical compound containing the C-14 isotope, placing the first and second electrodes in the sealed enclosure and electrically isolating them from each other, filling the electrolyte body. The C-14 isotope is introduced into the layer of carbon-containing materials on the surface of the first electrode. An alcohol solution of aniline hydrochloride containing the C-14 isotope is used as a chemical compound for impregnating an array of carbon-containing materials on the surface of the first electrode.

Technical result

The technical result of the utility model is to create a device for the accumulation of electric charge that does not require charging from an external source of electricity and increase the duration of the device without using an external charging energy source.

Brief Description of the Drawings

In FIG. 1 shows the design of a self-charging supercapacitor.

In FIG. 2 (a, b) presents the Design (a) and the appearance (b) of the investigated cell.

In FIG. Figure 3 shows a graph of the dynamics of the charge of a cell with aniline hydrochloride with an activity of C-14 equal to 1.74 and 6.0 mCi.

In FIG. Figure 4 shows the dynamics of the discharge of a cell with aniline hydrochloride with an activity of C-14 equal to 1.74 mCi.

In FIG. Figure 5 (a, b) shows the dynamics of the charge (a) and discharge (b) of a cell with an array of CNTs on a substrate impregnated with aniline hydrochloride with an activity of C-14 equal to 1.74 mCi in a cell filled with distilled water.

In FIG. Figures 6 (a, b) show the dynamics of the charge of a cell with aniline hydrochloride with an activity of C-14 equal to 6 mCi, with an electrolyte of 0.1 n H2S04 (a), and a change in the discharge current in the stationary mode at a load of 10 kOhm (b).

In FIG. 7 is a graph of the voltage and load current in the charge-discharge mode on a cell with aniline hydrochloride with an activity of C-14 equal to 6 mCi, with an electrolyte of 0.1 n H2S04.

In FIG. Figure 8 (a, b) shows the dynamics of the charge of a cell with aniline hydrochloride with an activity of C-14 equal to 6 mCi, with an electrolyte of 0.01 n NaOH (a), and a change in the discharge current in a stationary mode at a load of 10 kOhm (b).

Utility Model Implementation

The stated technical problem is solved by the fact that in the inventive device one of the electrodes of the capacitor is made with carbon nanotubes of CNTs containing radioisotopes with beta radiation. In this case, CNTs are made from the C-14 radioisotope, or from a mixture of C-14 radioactive isotopes with stable carbon isotopes. The introduction of carbon-14 into CNTs can be carried out in three ways:

a) directly at the stage of synthesis of CNTs by using liquid, solid or gaseous carbon-containing materials as raw materials, which contain C-14 (for example, volatile organic compounds, methane, CO or CO2, etc.);

b) by impregnating CNTs made from natural stable carbon with solutions or volatile gaseous compounds containing the C-14 isotope;

c) the functionalization of CNTs using electrochemical, thermal, electrospark, laser, magnetic, ion-beam or other processing, introducing atoms, radicals, functional groups containing the C-14 isotope into CNTs.

Other beta-decay radioisotopes can be deposited onto the CNT surface, for example, H-3, Ni-63, Sr-90, Kr-85, Am-241, Ac-227, Th-229 radionuclides, which can significantly increase the electron yield and supercapacitor charge.

In this case, a self-charging supercapacitor is realized in which charging is performed not from an external source of electricity, but by converting the energy of the electrons of the beta sources during their decay.

In FIG. 1 shows the design of a self-charging supercapacitor. It consists of a metal substrate (pos. 1), on which an array of carbon nanotubes (CNTs) that contain the C-14 radioactive isotope (pos. 2) is grown. The substrate is placed in a fluoroplastic housing (pos. 3), where it is in contact with the lower electrode (pos. 4), which has an external terminal (pos. 5). A separator (pos. 6) is placed on top of the active substrate, which prevents the mechanical contact of unlike electrodes and makes it difficult to mix cathode and anode electrolytes. The cell body is filled with electrolyte (pos. 7) and closed with a plastic cover (pos. 8). A second electrode (pos. 9) in contact with the electrolyte is inserted into the lid. The cap (key 8) seals the cell.

In FIG. 2a and FIG. 2b shows the design and appearance of the mockups of the investigated supercapacitor cells. The cell consists of a housing 1 and a cover 2 made of stainless steel, inside which a fluoroplastic housing 3 is placed, and a collector electrode 4, isolated from the cover by a fluoroplastic gasket 5. The test working electrode 8, in the form of a substrate, is mounted facing up on a rubber ring 6, pressed thereto a fluoroplastic insert 7. On the bottom side of the substrate, an electric wire with a connector is supplied by a spring contact with a screw. The cell is filled with electrolyte through a hole in the electrode 4.

For given geometric dimensions, the open visible area of the substrate was 0.5 cm2, and the electrical capacitance of the dry cell was 82 pF.

The preparation of substrates with CNTs was carried out by repeatedly applying to the nanotubes an alcohol solution of aniline hydrochloride containing the C-14 isotope. The determination of the activity of the deposited isotope was determined by calculation by measuring the mass of the substrates before and after impregnation with the reagent, using the characteristics of the specific activity measured by the calorimetric method. The carbon-14 isotope activity thus determined was 1.74 and 6 mCi for two different substrates of the same type. Additionally measured (β-flux from the substrate, equal to 0.8 × 105 and 2.25 × 105 min-1 cm-2).

Studies of the electrical characteristics of supercapacitor cells were carried out using a Sch-31 digital nanovoltmeter (measurements on dry and electrolyte-filled cells), as well as a specially prepared automated measuring system based on ADAM 4017+ analog-digital modules, which allows continuous measurements in automatic mode (cells with electrolyte filling).

The implementation of the utility model is illustrated by the following examples.

Example 1

Substrates with pre-formed one-sided coatings in the form of an array of CNTs with a thickness of ~ 10 μm are impregnated with an alcohol solution of aniline hydrochloride, in which about half of the carbon atoms are represented by the C-14 isotope. The total activity of C-14, determined by the increase in the mass of the substrates after drying, was 1.74 and 6.0 mCi for the first and second substrates, respectively. The substrates were placed in cells with the construction described above, and the voltage on the cell, determined by its charge due to beta decay of the C-14 isotope, was recorded. The charge kinetics of the dry cells are shown in FIG. 3.

The charge of the cells proceeds with the emission of negatively charged electrons, as a result of which the substrate with CNTs acquires a positive charge. After charging the cells during the day and reaching a voltage of about 400 mV, the cells were discharged on the load resistor with the voltage recorded on it. The cell discharge on the 10 kΩ resistor proceeded for fractions of a second, and on the 47 MOhm resistor, for several minutes. The discharge dynamics in the latter case is represented by the diagram in FIG. four.

The initial section of the cell discharge, which lasts about 10 minutes, follows an exponential trend. Further, a noticeable deviation from the exponent was observed, and in the stationary mode the discharge curve reaches a constant level, determined by the equality of the discharge velocities and the cell charge, the current of which is determined by the activity of the beta source on the substrate.

The experiments described above demonstrate the low efficiency of a dry cell when it is directly charged by beta decay electrons, since only an insignificant part of the decay electrons is involved in the cell charge process, reaching the collector electrode. In addition, part of the beta decay electrons compensates for the positive charge of the substrate, being absorbed in the CNT array on the substrate.

Example 2

A cell with a substrate with an activity of C-14 equal to 1.74 mCi, after experiments with the charge and discharge of a dry cell, was filled with distilled water. The characteristics of the charge and discharge of the cell were measured.

The dynamics of the voltage across the cell and the discharge current at the 10 kΩ load resistor is shown in FIG. five.

At the initial time for ~ 20 h, starting from the moment of filling with water, the cell efficiency is low due to the low ionic conductivity of pure water. The cell voltage at this stage for the most part did not exceed 50 mV. After the dissolution of some of the aniline hydrochloride from the substrate in water with the formation of additional ions in it, the voltage on the cell gradually increases over the next 10-12 hours. In stationary mode, the voltage on the cell stabilizes, approaching a constant value of ~ 300 mV, and is maintained at this level while water is present in the cell. At this stage, the load current of the cell on the 10 kΩ resistor (Fig. 5b) is stabilized, amounting to about 1 μA / cm2.

The described experiment shows that the efficiency of a condenser cell filled with distilled water as a converter and an electric energy storage device with an array of CNTs with carbon-14 is significantly higher than that of a similar cell without water.

Example 3

A cell with a substrate prepared as described in Example 1 with an array of CNTs impregnated with an aniline hydrochloride alcohol solution with an activity of C-14 equal to 6 mCi, after experiments with charge and discharge in a cell with distilled water, was dried, and then filled with electrolyte 0.1 n H2SO4.

The change in cell voltage is characterized by the time diagram shown in FIG. 6a, and the dynamics of the discharge current in stationary mode at a load of 10 kOhm is shown in FIG. 6b.

At the initial moment, the discharge current in the peak mode reaches 4 μA / cm2, after which it decreases to 1 μA / cm2, reaching the maximum values of 1.5 μA / cm2 in the intermediate period. The diagram also shows the finish portion of the discharge curve with a decrease in current to zero, corresponding to the evaporation (or radiolysis) of water from an unpressurized cell.

In FIG. 7. The diagram of the cell in the "charge-discharge" mode when using a load resistor of 10 kOhm is shown.

The diagram shows that at the time of connecting a 10 kΩ load resistor to the cell, the discharge current (curve 2) has a maximum value of 4–9 μA / cm2, decreasing within a few seconds to 2 μA / cm2. When the load resistor is disconnected, the voltage on the cell (curve 1) quickly increases due to internal charging, reaching 50-70 mV in two seconds, and rises to 90-100 mV by the end of the 5-second cycle.

Example 4

A cell with a substrate with an array of CNTs impregnated with an alcohol solution of aniline hydrochloride with an activity of C-14 equal to 6 mCi, after experiments with charge and discharge in a cell with 0.1 n H2SO4 described in the previous Example 3, was dried and then filled electrolyte 0.01 n NaOH.

The change in the cell voltage was characterized by the time diagram shown in FIG. 8a, and the dynamics of the discharge current in stationary mode at a load of 10 kOhm is shown in FIG. 8b.

In a cell with an electrolyte of 0.01 n NaOH, as well as in a cell with an electrolyte of 0.1 n H2S04, the double layer of a supercapacitor is self-charged due to beta decay energy with a steady state level of ~ 300 mV. The discharge current at a load of 10 kΩ at the initial time reaches 18 μA / cm2, then gradually decreases, assuming a value of ~ 40 μA / cm2 in steady state.

Thus, in experiments using electrolytic cells with electrodes in the form of substrates containing arrays of CNTs with the C-14 radioisotope, the operation of a self-charging supercapacitor was demonstrated. The device performs multiple charging and discharging without an external current source.

The above information indicates the following conditions are met when using the claimed utility model:

- a device in the form of a supercapacitor, embodying the claimed utility model in its implementation, accumulates and stores electrical energy without charging it from external energy sources;

- the claimed device for charging a supercapacitor uses beta decay of the C-14 isotope, whose half-life is 5700 years. When the device is sealed, the consumption of electrode materials and cell bodies made of corrosion-resistant alloys is minimal, there is no electrolyte consumption.

- for the claimed device and the method of its manufacture in the form described in the independent clauses of the stated utility model formula, the possibility of their implementation using the means and methods described in the application or known prior to the priority date is confirmed;

- a device embodying the claimed utility model in its implementation, is capable of achieving the achievement of the technical result perceived by the applicant.

The advantage of the utility model is that:

The efficiency of converting beta decay energy into electrical energy increases, which is expressed in an increase in the generated current and energy compared to analogues.

The cost of manufacturing a power source made in the form of a supercapacitor is reduced due to the use of the C-14 isotope - one of the cheapest (per unit of activity) and available on the market isotopes, as well as by simplifying the design and manufacturing technology of the device.

The proposed device can be implemented taking into account already existing experience in the manufacture of power devices for mobile devices using supercapacitor technology with electrodes that use coatings on the electrodes in the form of an array of carbon nanotubes.

Therefore, the claimed utility model meets the condition of "industrial applicability".

Features of achieving a technical result

Feature # 1 is that in a device that converts the energy of radioactive beta decay into electrical energy, a supercapacitor is used, the working electrode (s) of which is made in the form of a substrate with an array of carbon nanotubes.

Feature No. 2 is that the substrate with an array of carbon nanotubes is impregnated with a solution of a chemical compound that contains the C-14 isotope, or the carbon nanotubes are made using the C-14 isotope.

Feature 3 is that the substrate with an array of carbon nanotubes is placed in an electrolyte, in which the double layer formed at the interface between each individual nanotube in the array and the electrolyte, being an asymmetric potential barrier to the charges generated during decay, plays the role of an effective charge separator and at the same time an electric energy storage device.

Claims (8)

1. A supercapacitor, including: - sealed housing - the first and second electrodes placed inside the housing, electrically isolated from each other, one of which or both are also electrically isolated from the housing, - a separator installed between the electrodes - electrolyte filling the free volume of the cell and the space between the electrodes, characterized in that carbon-containing materials containing a mixture of radioisotopes with beta decay S-14, H-3, Ni-63, Sr-90, Kg-85 are deposited on the surface of the first electrode. 2. The supercapacitor according to claim 1, characterized in that the carbon-containing materials on the surface of the first electrode are deposited in the form of an array of carbon nanotubes (CNTs), fullerenes, graphene, carbon black, graphite, or a mixture thereof containing the C-14 isotope. 3. The supercapacitor according to claim 1, characterized in that the electrolyte is a solution of an acid, for example, H ₂ SO ₄ or HNO ₃ , an alkali, for example, NaOH or KOH, or a solution of salts, for example, KCl, NaCl, KNO ₃ , Na ₂ SO ₄ .

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