WO2014175756A1

WO2014175756A1 - The carbon electrode and method of carbon electrode manufacturing

Info

Publication number: WO2014175756A1
Application number: PCT/RU2013/000341
Authority: WO
Inventors: Sergey Gennadyevich ULYAKHIN; Viktor Andreyevich NIKITIN; Gleb Sergeyevich KURKIN; Anton Valeryevich GLOTOV; Vyacheslav Ivanovich SHUMOVSKII
Original assignee: Zakrytoye Aktsionernoye Obshchestvo "Elton"
Priority date: 2013-04-22
Filing date: 2013-04-22
Publication date: 2014-10-30

Abstract

The invention relates to the field of electric engineering, in particular, to the field of porous carbon electrodes manufacturing technique. The method of carbon electrode manufacture embodiment: mixing and homogenizing porous carbon material with conductive additive, polymer binder and a process liquid, homogenizing the obtained mixture, obtaining the granules of the mixture, rolling the granules through the roll-mill with obtaining a semifinished products in a form of strip, cutting the strip into pieces of specific shape, stacking of the pieces one on another in a continuous multiple-layer string with partial overlapping based on the assumption that the contact area between the adjacent pieces is essentially constant and predetermined value, pressing the string of pieces until a semi-product in a form of carbon strip is formed, drying the obtained semi-product and finally calendering the semi-product with obtaining the carbon electrode with required parameters.

Description

THE CARBON ELECTRODE AND METHOD OF CARBON

ELECTRODE MANUFACTURING

The present group of inventions relates to electronics, particularly, to the field of porous carbon electrodes manufacturing. The carbon electrodes obtained with the use of the method disclosed can accumulate electric charge due to the electric double layer formation on its surface and can be used in the energy storage devices of different types.

The energy generation and consumption are the constituents of human progress. There is a great number of different methods of electric energy generation, and significant number of different types of consumers. Depending on the method of energy generation, its transmission is possible by means of electric circuit (electrons and ions movement), physical movement of energy resources, etc. But except generation, transmission and consumption of electric energy, its storing is also required.

Electric energy storage devices are well known. One of the first electric energy storage devices is considered to be Voltaic cell. This device was invented back in 1800 and had two plates made of Cu and Zn, which were immersed in a jar containing acid. Thus, a so called «galvanic cell» has been developed. The most successful were the galvanic cells made on the base of lead acid system. These devices have been developed more than 100 years ago and up to now are the most widely spread electrochemical energy storage devices.

Electrostatic capacitors as electric charge (and, relatively, electrical energy) storage devices have been developed even earlier. First records about the devices similar by their operation principle with the state of the art electrostatic capacitors were dated 1745 when the so-called «Leyden jar» has been invented. The method of electric energy storage in electrostatic capacitor concerns the polarization effect - phenomenon of spatial separation of charges. Electric energy accumulated in a capacitor is determined according to formula E = CU²/2, where U - voltage between the capacitor plates in Volts and C - capacitance value in Farads. In particular, capacitance of plane capacitor, wherein the plates comprise two parallel conductors with surface area S and distance d between them placed in a media with dielectric permeability ε is calculated by formula E = E£oS/d, where εο - electric constant, numerically equal to 8.85418782 ^χ lO-^ Fnr¹. Capacitance values of the modern electrostatic capacitors can be as high as several farads.

One of the most perspective electric energy storage devices is supercapacitor (ultracapacitor, double layer capacitor, electrochemical capacitor, EDLC, etc.). The principle of operation of electrochemical capacitor concludes in electric double layer formation at the electrode-electrolyte interface, comprising the pairs of positive and negative charged particles - ions, electrons and holes. The capacity of supercapacitors, as in case of traditional electrostatic capacitors, is determined substantially according to formula E = ££oS/d. Double layer capacitor has been developed and patented by General Electric company back in 1957. Usually, conducting materials with high specific surface area are used as the electrodes of double layer capacitors. In particular, these are various porous carbon materials produced of natural or synthetic raw materials.

One of the most prospective materials for the carbon electrodes are porous carbon powders, produced from plants or mineral raw materials by the activation method. The main advantage of such materials is their high specific surface area, reaching several thousand m²/g, as well as relatively low cost. For the purpose of providing better electric contact between particles of porous carbon powder and outer electric circuit, the electrodes are made from porous powders together with binding material and further formation of sheets or films of a certain thickness, having direct electrical contact with current collector. As a rule, the latter comprise the material with high conductivity - usually more than 10³ Sm/cm and more than 0,1 Sm/cm². The contact between the active electrode material and current collector is often provided by means of electrically conductive adhesive or by another material, which demonstrates the characteristics of high adhesion both to the current collector and to the porous active material. In some, cases, instead of electrically conductive adhesive, electric contact is provided by means of mechanic pressure between the current collector and the active material.

As mentioned above, while manufacturing the carbon electrodes in a form of sheets and films on the base of porous materials, different binder materials are used. It should be noted that binder must, on the one hand, provide mechanical (and, relatively, electrical) contact between the particles of the active material. Frequently it requires using the relatively large amount of binder. Moreover, binder is often selected from a number of thermoplastic polymers (for example, polyethylene, polypropylene, etc.), which don't possess intrinsic porosity and, therefore, the space, occupied by this binder, is unavailable for the ions of electrolyte. It is also evident that adding the binder into composite material decreases the amount of porous material contained in the electrode. This fact directly influences the capacitance and efficiency of electrochemical capacitors.

To decrease binder impact on the specific capacitance and energy parameters of the carbon electrodes, the cold flow capable polymeric materials are used. They can form fibrillar matrix under the influence of the shear forces applied to the composite having such binder. Therefore, the electrodes of majority of commercial supercapacitors are produced with the use of polytetrafluorethylene (further referred to as - PTFE) as a binder. Another advantage of PTFE is its exclusive chemical and electrochemical resistance. In addition, PTFE is more or less cheaper and commercially available material. PTFE is used in a form of powders or dispersions, which are further mixed homogeneously with powders or dispersions of porous carbon materials.

To increase electric conductivity of the carbon electrodes the special electrically conductive additives are introduced. Such additives generally include carbon black, graphite, nanotubes, nano-graphene, metal powders and shavings, insertion of the conductive grid into the active material, etc.

In modern electrochemical capacitors with aqueous and organic electrolytes the carbon sheets and films on the base of different porous carbon materials are used as polarizable electrodes. Various carbon powders are known as constituents of the symmetrical and asymmetrical supercapacitors with high specific surface area (500 - 3000 m²/g) and providing specific capacitance as high as 50 - 300 F/g.

Up to now various technologies for the carbon sheets and strips manufacturing are known, which are wide spread in production of electrochemical capacitors of different systems with aqueous and organic electrolytes. In process of carbon sheets and strips manufacturing the porous carbon powders with high specific surface area, polymeric binder materials, conductive additives and, as a rule, different process liquids required for the technological operations.

One of the wide spread among the well known methods of the porous carbon electrodes manufacturing is the method of the strips rolling from granules. This method is often used in production of double-layer capacitors of a jelly roll structure: two electrodes in a form of thin layers on the surface of current collector divided by a separator are coiled into a roll (see. patent RU 2427052 CI, published on 20.08.2011). When using this structure, the thickness of porous carbon layer usually lies in the range of 0,05 to 0,5 mm (see. patent US6713034 published on 30.03.2004). The method of electrode strip manufacturing in such case implies the usage of a mixture of the dry carbon powders and a process liquid with subsequent stepped rolling in one direction by means of multiple-roll calender with rolls diameter ranging from 40 to 350 mm until a necessary thickness is achieved. Manufacturing techniques are fully described by the authors of US patents #6778379 B2, published 02.09.2004 and US patent #7160615 B2, published 03.06.2004. The US patent #4153661 published on 08.05.1979 describes the method of the composite sheets manufacturing on the base of different powders and PTFE as a binder. According to description, composite material formation is provided by means of preliminary mixing the PTFE dispersion with the filler in powder state and followed by a biaxial rolling of the obtained pasty mass through a calender several times with half-and-half product folding or decreasing calendar rolls gap between the stages of rolling. This method enables to produce composites of high homogeneity and mechanical strength. One of the main drawbacks of such process is its low productivity specified by use of a number of the repeating operations. It makes scaling of this process in commercial production quite complicated.

The patent US 6602742 B2 published on 25.07.2002 describes the method of supercapacitor carbon electrodes production including the following steps: mixing porous carbon material, conductive additive, fluorinated polymer binder, process liquid and temporal additive in a form of polypropylene carbonate, relieving the process of indicated mixture extrusion. Further after the electrode sheets formation the temporal additive is completely removed by means of heat treatment at 250 °C. According to description, this method allows to produce carbon electrodes with thickness ranging from 50 to 150 microns.

The method of carbon electrode manufacturing described by the authors of the US patent #8213156 B2 published on 13.05.2010 shows a possibility of only dry ingredients using during the carbon electrode manufacturing and, in its turn, eliminating a number of stages having negative impact on the purity of the carbon electrodes obtained. Special attention is paid to mixing the porous carbon powders with the particles of a dry polymeric binder by means of a jet mill, which ensures strong shear forces allowing the polymer particles to fibrillate. Further, powder is subjected to a single-step calendering with subsequent carbon strip of possible thickness from 100 to 250 microns obtaining. The latter restricts using this method for the manufacturing of carbon electrodes with high thickness. Another method of the supercapacitor carbon electrode material manufacturing is described in the patent application US 20110204284 Al published 25.08.2011. This method is the closest prototype of the proposed invention. According to the description, blending of porous carbon powder, carbon-black, polymer binder and a process liquid is done with subsequent extruding and benched flattening of carbon electrode in a form of strip. Technology involves the use of special additives, notably, at least the second binder, for example, styrene butadiene rubber in the amount of 0,1 to 5% and another additive, functioning as absorption material for process liquid, required for the continuous extrusion process. It should be noted that any substances, composing the electrode material, will contribute to the operating parameters of the capacitor. In most cases, any additional substances required for the implementation of a certain technology, are considered as pollutants and require further removal, for instance, by means of heat treatment or washing that in its turn makes production process more complicated and expensive. Also, according to the description this technology allows to produce carbon electrode materials with thickness from 30 to 250 microns.

According to the data given in the article (Serbinovskyi M.Y., Dumchus A. M., Shkurakov V.L. Influence of molding process parameters upon the electrode strip density // Electrochemical power engineering, 2001. T.3. - P.74-79), for the manufacturing of carbon electrode with thickness of 500 microns at a single pass directly from granules, rolls' diameter should be about 0,5 m, and in case of carbon electrode manufacturing with thickness of 1000 microns and more, rolls over 2 m in diameter are required. The authors describe the method of strip formation by rolling the active mass from granulated active carbon materials, impregnated by a process liquid, by means of a roll mill with rolls diameter ranging from 40 to 350 mm with changeable gap between the rolls. Dry active mass of carbon electrodes contained carbon black and fluoroplastic binder in the amount of 8-10%. Thereby, carbon electrode manufacturing by a single-stage rolling becomes unacceptable in the case of necessity to produce carbon electrodes with thickness more than 1000 microns. The requirements to a large diameter of rolls are critical during formation of electrode material because the characteristics of the carbon electrodes of specific thickness are directly dependent on the rolls diameter. Besides the difficulties relating to manufacturing of carbon electrode with thickness more than 1000 microns, this method has one more significant drawback. As there is only one direction calendering, the mechanical and electrical characteristics in the machine and transverse directions may differ. It is explained by the internal processes, occurring in the material structure during rolling. During such material passing through the calender rolls, the binder generates the internal connections (fibrills, strands, fibres], basically, in the calendering direction. Therefore, in order to provide isotropy of the carbon electrode's mechanical and electrical properties, it is necessary to ensure rolling in all directions, which is impossible by using of the existing methods. Anisotropy of the electrode properties has an impact on the specific capacitance and specific energy parameters of the electrodes. In particular, electrodes manufactured by a single-pass rolling possess anisotropy of electrical resistance, which may lead to effectiveness decreasing of electric energy storage devices made with use of such electrodes.

The objective of the invention is improving the manufacturing methods of carbon electrode, having thickness more than 1000 microns. By using this method it is possible to produce the active material of carbon electrodes used in the electrochemical capacitors and hybrid energy storage devices.

To meet this objective, the manufacturing method of carbon electrode has been developed, composed of, but not limited to, porous carbon material, conductive additive and polymeric binder, wherein:

a. porous carbon material, conductive additive, polymer binder and a process liquid are homogeneously mixed together to form a pasty substance.

b. extraction of granules from the mixture obtained on the stage a); c. rolling of granules obtained on the stage b), through a roll mill with obtaining an intermediate product in a form of a strip;

d. cutting of a strip obtained on the stage c) into pieces of a certain shape;

e. placing the pieces obtained on the stage d) one on another in a continuous multiple-layer string with partial overlapping on the assumption of the fact that the contact area between adjacent pieces is essentially constant and predetermined;

f. pressing the string of pieces, obtained on the stage e), until the half- finished product in a form of a carbon strip with uniform thickness is obtained; g. drying the half-finished product, manufactured on the stage f);

h. calendering the half-finished product, manufactured on the stage g) with obtaining a carbon electrode with the required parameters.

Homogenizing the mixture containing porous carbon and conductive additive can be carried out by a mill.

Blending and homogenizing the mixture containing the porous carbon, conductive additive, polymer binder and a process liquid can be carried out by a twin-screw extruder or a continuous mixer with co-rotating screws.

The length and screws diameter (L:D) ratio may vary from 10:1 to 40:1;

The temperature of, at least, a part of a material cylinder of extruder or a continuous mixer in the process of operation may be selected from the range 20 - 100 °C;

Distilled or deionized water may be used as a process liquid.

Organic solvent may be used as process liquid.

The amount of process liquid in relation to the dry components may be selected from the range of 1,5:1 - 3:1.

Process liquid may be added on the stage of mixing in an extruder or a continuous mixer. Process liquid may be added before the stage of mixing in an extruder or a continuous mixer.

The material granules may be 1-5 mm in size;

Strip may be cut into parallelogram-shaped pieces;

At least one of the parallelogram vertices angle may be equal to 45 - 90°.

Pressing the parallelogram-shaped pieces may be executed by means of the caterpillar press.

Caterpillar press may contain two continuous conveyor belts, arranged one above the other.

The gap between the conveyor belts may depend on the size of the pieces being pressed.

The gap between the conveyor belts may depend on a number of pieces, arranged one above the other in a string before rolling through a caterpillar press.

The gap between the conveyor belts at the caterpillar press output may be, at least, not higher than the total thickness of the string of pieces, fed into the caterpillar press.

Pressing the parallelogram-shaped pieces may be executed by means of the multiple-roll press.

Rolls may be arranged in pairs.

The gap between the rolls arranged in pairs may be set, based on the thickness of the semi-products string, fed into the multiple-roll press.

The gaps between the rolls arranged in pairs may be set, based on the quantity of the finished products, arranged one above the other.

Number of rolls in the multiple-roll press may be selected from a range of 4-

40.

Maximum distance between the rolls, relating to different pairs, may not exceed maximum dimensions of the semi-finished products, feeding to the multiple-roll press. The strip cutting into pieces, their subsequent stacking, compaction and calendering may be repeated several times.

Drying may be carried out at the atmospheric pressure and the temperature of 20 - 300 °C .

Carbon strip drying duration may be chosen from the range 1 - 10 hours.

Drying may be carried out at the low pressure.

Pressure may be chosen from the range 0.1 - 0.5 bar.

Drying period at low pressure may last from 10 to 120 minutes.

Calender rolls diameter may be selected from the range 90 - 1000 mm.

Temperature of calender rolls can be selected from the range 20 - 100 °C.

Furthermore, the carbon electrode has been developed based on the above described method, actually presenting a sheet composed of porous carbon material, containing conductive additive and polymer binder, characterized by a thickness lying in the range of 1-3 mm, electrical resistance uniformity along the carbon electrode area not higher than 10%, density lying in the range 0.6 - 0.7 g/cm³, tensile strength not less than 0,1 MPa, specific electrical capacitance in the sulphuric acid electrolyte equal to 1200 - 1600 F/g, capacitance density in sulphuric acid electrolyte is equal to 750-900 F/cm³.

Porous carbon material may comprise the powder with particles 0,5-10 microns in size.

Porous carbon material may be characterized by a specific surface area value equal to 500 - 3000 m²/g.

Content of porous carbon material in carbon electrode may be selected from the range 80-99%.

Carbon black, graphite powder, carbon nanotubes, graphene nanosheets or their mixture may be used as a conductive additive.

Content of conductive additive in carbon electrode may be selected from the range 0-15%.

PTFE may be used as a polymer binder. Content of polymer binder may be selected from a range of 1-10%.

Electric energy storage device has also been developed, containing, as a minimum, one carbon electrode, manufactured by the method being suggested, together with current collector, minimum one counter electrode, electrolyte, a separator and a body with terminals where the indicated components are placed.

Besides, a vehicle has been developed and manufactured with the use of such energy storage device.

Stationary energy storage system has been additionally developed using suggested electric energy storage device.

The essence of the present invention concerns to the development of a new continuous manufacturing method of the carbon electrode material for the chemical current source device which demonstrates characteristics of high specific capacitance and energy. The method implies initial mixing the carbon electrode components, partial fibrillation of the binder, granulating the obtained mass, forming a strip by means of a roll mill or a calender, cutting the strip into pieces, their imposition one above the other and further mutual pressing at some angle to the initial rolling direction.

The suggested group of inventions is described in the drawings below.

Fig.l Technological flowchart of the carbon electrode manufacturing.

Fig.2 Active mass granulation and carbon strip formation process.

Fig.3 Continuous carbon strip manufacturing process.

Fig.4 Formation of the continuous carbon strip out of the multilayer string by a multiple-roll press.

Fig.5 Vehicle made with the use of energy storage device containing carbon electrode.

Fig.6 Stationary energy storage system, using energy storage device, containing carbon electrode. The invention embodiment is using the mechanism of the semi-finished products stacking and rolling at different angles for continuous manufacturing of carbon electrode with thickness not less than 1000 microns having isotropic mechanical and electrical characteristics.

In order to implement continuous manufacturing of the carbon electrode with thickness not less than 1000 microns with isotropic mechanical and electrical characteristics, the mechanism of the products rolling at different angles has been developed according to the present invention. The process flowchart of carbon electrodes manufacturing is shown in Fig.l. According to this technology, in order to produce such electrode, the porous carbon powder is used (1) with high porosity and specific area. To increase electrical conductivity and achieve high homogeneity of the capacitive and energy parameters, it is necessary to use the conductive additive, such as nonporous carbon powder (2). Since the carbon materials are often delivered in granules with relatively large sizes, according to the present invention preliminary blending or grinding (5) of the fine-dispersed nonporous carbon powders together with porous carbon powders for the purpose of their homogenization may be applied. The conditions and duration of the materials dispersion depend on the initial and final parameters of particles distribution pursuant to their sizes. One of the most effective methods of homogeneous blending of active carbon material with conductive additive is their mutual grinding in a ball mill or a vibration mill. Grinding bodies made of sturdy materials which do not contain or isolate hazardous chemical elements are often used during operation process.

Upon completion of the homogenization stage the process liquid (3) and the polymer binder (4) are added to the indicated carbon-carbon mixture, afterwards additional blending of the indicated components and homogenization of obtained mixture is carried out (6), as a result the carbon-polymeric composition containing process liquid is obtained. Duration and conditions of homogenization depend on electrode material parameters, characteristics of binders and used materials. The obtained carbon-polymeric substance represents the initial material for the carbon electrode formation. The required properties of carbon electrodes manufactured by the method described are achieved by means of further mechanical interaction of the components at certain conditions. As a result of such interaction, polymer binder network composed of fibrils is formed under the active shear deformations inside the material containing such a binder.

The substance containing porous carbon powder, conductive additive, process liquid and partially fibrillated binder is fed to the device allowing making granules with specific size distribution (7). The composition of the substance is to be selected such that the granules obtained do not stick to each other during their handling.

The produced granules are fed to the hopper located directly over the rolls of a roll-mill. After passing through the roll-mill, the granules are formed in a continuous carbon strip [8) with a certain thickness. It should be noted that the mechanical and electrical characteristics of a carbon strip obtained at this step will differ in parallel and perpendicular directions towards rolling direction. To be noted as well, that the carbon strip manufactured at this process usually has multiple defects such as holes and cracks.

To eliminate the defects, the obtained semi-finished product in a form of a strip is cut into substantially equal pieces of a specific predetermined shape [9], which are then laid on the conveyor belt where they are subsequently stacked in a continuous string of multiple layers (10). The continuous string of pieces is delivered to the caterpillar press or multiple-roll calender, where pressing (11) of the obtained multi-layer structure is carried out till the layers are physically connected into a single strip. The next stage is the calendering (12) of the strip obtained to provide high thickness uniformity. As a result of the procedures mentioned above the homogenous semi-finished product in a form of a carbon strip and, substantially, having no defects and with high mechanical strength as compared to the initial material is manufactured. To decrease anisotropy of the mechanical properties, density increase, as well improvement of electrical and physical parameters of the carbon, the operations (9) - (12) can be repeated several times.

The next stage is drying procedure (13). Drying process has a substantial impact on the characteristics of the manufactured carbon strip. This process can be carried out (but not limited) by using the infrared heaters, by means of hot air or in a vacuum. The purpose of drying is removal of, at least, a part of a process liquid. As far as the manufactured carbon strips consist of, significantly, porous carbon materials, the considerable part of a process liquid is contained in the pores of a carbon material. Liquid is usually slowly removed from the porous material, therefore the drying duration should be in the range of 1 - 10 hours, depending on the pore sizes of the carbon powder, temperature of thermal drying and a process liquid volatility. Drying temperature is selected thus not to lead to irreversible changes of parameters of carbon powders (1, 2), binders (3) and a process liquid (4). This procedure is also affective at a lower pressure.

After the semi-finished carbon strip is formed and dried its calendering is carried out (14). This process may be performed by means of a two- or multiple- roll calender with rolls of specific diameter, heated up to the required temperature. Calendering process provides high density and certain thickness to the manufactured carbon electrode.

This invention allows to produce electrode active material of super capacitor with thickness not less than 1000 microns, allowing to increase specific electrical, energy and performance parameters of supercapacitors and hybrid energy storage devices and is characterized by a resistance of not higher than 1 Om*cm, resistance uniformity along the surface not higher than 10% and a tensile strength in all directions not less than 0.1 MPa. The produced electrodes are applicable for the manufacture of electric energy storage devices with high specific capacitance. They can be used both in stationary electric energy storage systems and vehicles. Exemplary embodiments: Example 1

1. The original powders of the activated carbon powder with size of 7 microns (D50) and carbon black were mutually grinded in a vibrating ball mill MB-001 in proportion 10 parts of porous carbon powder to 1 part of acetylene black.

2. Isopropyl alcohol of 200% mass concentration relative to dry components was used as a solvent.

3. PTFE suspension of 6% mass concentration in relation to dry components was used as a binder.

4. Mixing of all components was performed in a planetary mixer during 10 minutes until a pasty substance is formed.

5. The obtained pasty substance was transported to the mechanical grater with holes of 2 mm in diameter.

6. 1-3 mm sized granules were supplied to hopper, located above the horizontal rolls with diameter of 240 mm and a gap of 0,5 mm between them.

7. The strip obtained as a result of previous stage was cut into separate pieces of rhomb shape with one of the angles at the vertex of 60°. Each side of rhombs were 0,25 m in length.

8. The pieces were continuously laid one on the other in direction parallel to one of the rhombs sides in 5 layers with 50 mm horizontal displacement between them and rolled through a cascade of 3 pairs of 100-mm rolls with the gaps of 3 mm, 2 mm, 1 mm between them, respectively. As a result, a 1-mm strip has been obtained.

9. The strip obtained at the previous step was exposed to recurrent cutting into separate pieces of rhomb shape with one of the vertex angles of 60°. Each side of rhombs were 0,25 m in length. 10. The pieces obtained at the previous step were continuously laid one above the other in direction parallel to one of the rhombs sides in 5 layers with 50 mm horizontal displacement between them and rolled through a caterpillar press with initial gap of 6 mm and final gap of 4 mm between the belts. As a result, a 4- mm strip has been obtained.

11. The strip obtained at the previous step was put on a smooth horizontal surface and exposed to drying in the drying chamber at the temperature of 130°C during 4 hours.

12. The dried strip was fed into a calender with heated rolls having diameter 250 mm with a gap of 2 mm between them.

13. The carbon strip obtained has the following characteristics:

• Thickness - 2.15mm;

• Average specific electrical resistance - 0,85 Om*cm;

• Electric resistance non-uniformity over the surface - 0.05 Om*cm;

•Average tensile strength - 0,26 MPa

• Unevenness of tensile strength - ±0.01 MPa.

• Density - 0.63 g/cm³

• Specific electrical capacitance in sulfuric acid electrolyte - 1321 F/g.

• Capacitance density in sulfuric acid electrolyte - 858 F/cm³.

14. An asymmetrical electrochemical capacitor was assembled, containing 20 carbon electrode sheets, 11 current collectors, 10 lead-oxide electrodes, a separator, electrolyte in a form of 35% aqueous solution of sulfuric acid and a box containing the indicated components. Maximum capacity of the device was equal to 260 Ah, and specific energy - 0,17 MJ/kg.

15. The electric energy storage devices in the amount of 6 pieces were connected in series and mutually with control charge-discharge equipment and a power inverter installed on a transportation device containing internal combustion engine. As a result, energy saving due to the braking energy recuperation reached 40%. 16. The electric energy storage devices in the amount of 6 pieces were connected in series and mutually with control charge-discharge equipment and a power inverter were used as uninterruptible power supply. As a result, a continuous load of 500 W was kept operating during 4 h 45 m.

Example 2

1. Carbon black was exposed to grinding in a bead mill together with deionized water. The colloidal dispersion obtained was a 6% aqueous solution of acetylene black in water.

2. A colloidal dispersion of carbon black was mixed with porous carbon powder in 1:10 proportion during 3 minutes using a planetary mixer.

3. PTFE dispersion in the amount of 6% mass concentration in relation to dry components was used as a binder.

4. Carbon materials dispersions were mixed with PTFE binder solution within 3 minutes using a planetary mixer.

5. The obtained pasty mass was transported to the mechanical grater with holes of 2 mm in diameter.

6. 1-3 mm sized granules were supplied to hopper, located above the horizontal rolls with diameter of 240 mm and a gap of 1 mm between them.

7. The strip obtained at the previous stage was cut into separate pieces of rhomb shape with one of the angles at the vertices of 60°. Each side of rhombs were 0,25 m in length.

8. The pieces were continuously laid one on the other in direction parallel to one of the rhombs sides in 5 layers with 50 mm horizontal displacement between them and rolled through a cascade of 3 pairs of 100-mm rolls with the gaps of 5 mm, 4 mm, 3 mm between them, respectively. As a result, a 3-mm strip has been obtained. 9. The strip obtained at the previous step was put on a smooth horizontal surface and exposed to drying in the drying chamber at the temperature of 130°C during 5 hours.

10. The dried strip was fed into a calender with heated rolls having diameter 250 mm with a gap of 2 mm between them.

11. The carbon strip obtained has the following characteristics:

• Thickness - 2.16 mm;

• Average specific electrical resistance - 0,82 Om*cm;

• Electric resistance non-uniformity over the surface - 0.05 Om*cm;

•Average tensile strength - 0,19 M Pa

• Unevenness of tensile strength - ±0.04 MPa.

• Density - 0.61 g/cm³

• Specific electrical capacitance in sulfuric acid electrolyte - 1342 F/g.

• Capacitance density in sulfuric acid electrolyte - 855 F/cm³.

12. An asymmetrical electrochemical capacitor was assembled, containing 20 carbon electrode sheets, 11 current collectors, 10 lead-oxide electrodes, a separator, electrolyte in a form of 35% aqueous solution of sulfuric acid and a box containing all the indicated components. Maximum capacity of the device was equal to 260 Ah and specific energy - 0,17 MJ/kg.

13. The electric energy storage devices in the amount of 6 pieces were connected in series and mutually with control charge-discharge equipment and a power inverter were installed on a transportation device containing internal combustion engine. As a result, energy saving due to the braking energy recuperation reached 40%.

14. The electric energy storage devices in the amount of 6 pieces were connected in series and mutually with control charge-discharge equipment and a power inverter were used as uninterruptible power supply. As a result, a continuous load of 500 W was kept operating during 4 h 45 m. Example 3

1. Premixing of porous carbon powder and electrically conductive carbon black in the ratio 10:1 was carried out in a planetary mixer during 10 minutes.

2. Distilled water in the amount of 180% by weight of the dry components was added to the mixture of carbon materials and additional mixing was done during 10 minutes.

3. The mixture of PTFE suspension and water in the amount of 12% of the dry components was added to the colloidal solution obtained and then mixing was continued for 5 additional minutes.

4. Obtained pasty substance was fed to the lab extruder with screws diameter of 35 mm, L:D - 40:1. Rotation speed - 64 rpm, temperature of material cylinder - 25°C.

5. The obtained pasty substance was then transported to the mechanical grater with holes of 2 mm in diameter.

6. 1-3 mm sized granules were supplied to the hopper, located above the horizontal rolls with diameter of 240 mm and a gap of 1 mm between them.

8. The pieces obtained at the previous step were continuously laid one above the other in direction parallel to one of the rhombs sides in 5 layers with 50 mm horizontal displacement between them and rolled through a caterpillar press with initial gap of 6 mm and outlet gap of 4 mm between the belts. As a result, a 4- mm strip has been obtained.

9. The strip obtained at the previous step was fed into a calender with heated rolls having diameter 250 mm with a gap of 2 mm between them. 10. The strip obtained at the previous step was exposed to recurrent cutting into separate pieces of rhomb shape with one of the vertex angles of 60°. Each side of rhombs were 0,25 m in length.

11. The pieces obtained at the previous step were continuously put one above the other in direction parallel to one of the rhombs sides in 5 layers with 50 mm horizontal displacement between them and rolled through a caterpillar press with initial gap of 10 mm and final gap of 8 mm between the belts. As a result, a 8- mm strip has been obtained.

12. The strip obtained at the previous step was fed into a calender with heated rolls having diameter 250 mm with a gap of 4 mm between them.

13. The strip obtained at the previous step was put on a smooth horizontal surface and exposed to drying in the drying chamber at the temperature of 130°C during 5 hours.

14. The dried strip was fed into a calender with heated rolls having diameter 250 mm with a gap of 2 mm between them.

15. Additional drying has been carried out at the ambient pressure and 130°C during 1 hour.

16. The carbon strip obtained has the following characteristics:

• Thickness - 2.13 mm;

• Average specific electric resistance - 0,65 Om*cm;

• Unevenness of specific electrical resistance over the surface - 0.05 Om*cm;

• Average tensile strength - 0,30 MPa.

• Unevenness of tensile strength - ±0.02 MPa.

• Density - 0.64 g/ cm³.

• Specific electrical capacity in sulfuric electrolyte - 1315 F/g.

• Capacitance density in sulfuric acid electrolyte - 834 F/cm³.

17. An asymmetrical electrochemical capacitor was assembled, containing 20 carbon electrode sheets, 11 current collectors, 10 lead-oxide electrodes, a separator, electrolyte in a form of 35% aqueous solution of sulfuric acid and a box containing all the indicated components. Maximum capacity of the device was 250 Ah and specific energy - 0,16 MJ/kg.

18. The electric energy storage devices in the amount of 6 pieces were connected in series and mutually with control charge-discharge equipment and a power inverter were installed on a transportation device containing internal combustion engine. As a result, energy saving due to the braking energy recuperation reached 40%.

19. The electric energy storage devices in the amount of 6 pieces were connected in series and mutually with control charge-discharge equipment and a power inverter were used as uninterruptible power supply. As a result, a continuous load of 500 W was kept operating during 4 h 20 m.

Example 4

1. Premixing of porous carbon material powders and electrically conductive carbon black in the ratio 10:1 was carried out in a planetary mixer during 10 minutes.

4. A carbon pasty substance obtained at the previous step was fed to the lab extruder with screws diameter of 35 mm, L:D - 40:1. Rotation speed - 64 rpm, temperature of material cylinder - 25°C.

5. The obtained pasty substance was transported to the mechanical grater with holes of 2 mm in diameter. 6. 1-3 mm sized granules were supplied to hopper, located above the horizontal rolls with diameter of 240 mm and a gap of 1 mm between them.

8. The pieces obtained at the previous step were continuously laid one above the other in direction parallel to one of the rhombs sides in 5 layers with 50 mm horizontal displacement between them and rolled through a caterpillar press with initial gap of 6 mm and final gap of 4 mm between the belts. As a result, a 4- mm strip has been obtained.

9. The strip obtained at the previous step was fed into a calender with heated rolls having diameter 250 mm with a gap of 2 mm between them.

10. The strip obtained at the previous step was exposed to recurrent cutting into separate pieces of rhomb shape with one of the vertex angles of 60°. Each side of rhombs were 0,25 m in length.

11. The pieces obtained at the previous step were continuously laid one above the other in direction parallel to one of the rhombs sides in 5 layers with 50 mm horizontal displacement between them and rolled through a caterpillar press with initial gap of 10 mm and final gap of 8 mm between the belts. As a result, a 8- mm strip has been obtained.

12. The strip obtained at the previous step was fed into a calender with heated rolls having diameter 250 mm with a gap of 2 mm between them.

14. The carbon strip obtained has the following characteristics:

• Thickness - 2.21 mm;

• Average specific electric resistance - 0,69 Om*cm; • Unevenness of specific electrical resistance over the surface - 0.07 Om*cm;

• Average tensile strength - 0,17 MPa.

• Unevenness of tensile strength - ±0.01 MPa.

• Density - 0.52 g/cm³.

• Specific electrical capacity in sulfuric electrolyte - 1338 F/g.

• Capacitance density in sulfuric acid electrolyte - 728 F/cm³.

15. An asymmetrical electrochemical capacitor was assembled, containing 20 carbon electrode sheets, 11 current collectors, 10 lead-oxide electrodes, a separator, electrolyte in a form of 35% aqueous solution of sulfuric acid and a box containing all the indicated components. Maximum capacity of the device was 220 Ah and specific energy - 0,14 MJ/kg.

16. The electric energy storage devices in the amount of 6 pieces were connected in series and mutually with control charge-discharge equipment and a power inverter were installed on a transportation device containing internal combustion engine. As a result, energy saving due to the braking energy recuperation reached 35%.

17. The electric energy storage devices in the amount of 6 pieces were connected in series and mutually with control charge-discharge equipment and a power inverter were used as uninterruptible power supply. As a result, a continuous load of 500 W was kept operating during 4 h 00 m.

The invention was disclosed with reference to the specific embodiments thereof. A specialist can also assume any other embodiments close to the present description by its essence. The invention should be considered limited only by the content of the mentioned below patent formula and claims thereof.

Claims

Patent Claims:

1. A manufacturing method for carbon electrodes consisting essentially of a porous carbon material, conductive additive and the polymer binder in accordance with the following steps:

a. porous carbon material, conductive additive, polymer binder and a process liquid are homogeneously mixed together;

b. granules are extracted from the mixture obtained on the step a);

c. granules obtained on the step b) are passed through the two rolls with obtaining a strip of carbon-polymer material;

d. strip obtained on the stage c) is cut into pieces of predetermined shape;

e. pieces obtained on the step d) are laid one on another in a continuous multi-layer string with partial overlapping in a way that the contact area between adjacent pieces is essentially constant and predetermined.

f. string of pieces obtained on the step e) is fed into a continuous press at a certain angle towards the initial direction until a single strip-shaped semiproduct is formed;

g. semi-product obtained on the step f) is calendered;

h. calendered semi-product obtained on step g) is dried to remove at least a part of a process liquid;

i. semi-product obtained on the step h) is subjected to final calendering so that a carbon electrode with the required properties is obtained.

2. The method as in claim 1, wherein porous carbon and conductive additive are preliminarily mixed together in a mill or a mixer.

3. The method as in claim 1, wherein mixing and homogenizing the porous carbon material, conductive additive, polymer binder and a process liquid is carried out by means of a twin-screw extruder or a continuous mixer with co- rotating screws.

4. The method as in claim 3, wherein the ratio between the screw length and the screw diameter (L:D) is chosen from the range of 10:1 to 40:1;

5. The method as in claim 3 wherein the temperature of at least a part of the extruder material cylinder or continuous mixer is selected from the range of 20-100 °C;

6. The method as in claim 1, wherein distilled or deionized water is used as a process liquid.

7. The method as in claim 1, wherein organic solvent is used as a process liquid.

8. The method as in claim 1, wherein the mixture of organic solvent and water is used as a process liquid.

9. The method as in claim 1, wherein the amount of a process liquid in relation to dry components is selected from the range 1,5:1 - 3:1.

10. The method as in claim 1, wherein the manufactured granules of the material are 1-5 mm in size;

11. The method as in claim 1, wherein the strip is cut into separate parallelogram-shaped pieces;

12. The method as in claim 11, wherein at least one angle at the parallelogram vertices is equal to 45 - 90°.

13. The method as in claim 1, wherein the continuous pressing of a string of the pieces is carried out using the caterpillar press.

14. The method as in claim 13, wherein the caterpillar press contains two continuous conveyor belts, located one above the other.

15. The method as in claim 14, wherein the gap between the conveyor belts is a value dependent on the dimensions of the pieces being pressed.

16. The method as in claim 14, wherein the gap between the conveyor belts is the value, dependent on a number of the pieces, stacked one on another before rolling through the continuous press.

17. The method as in claim 14, wherein the gap between the conveyor belts at the caterpillar press outlet is, at least, not higher than the total thickness of the string of pieces stacked together before feeding to a caterpillar press.

18. The method as in claim 1, wherein the continuous pressing of a string of the pieces is carried out using the multiple-roll calender.

19. The method as in claim 18, wherein the rolls are combined in pairs.

20. The method as in claim 19, wherein the gaps between the rolls combined in pairs is set based on the thicknesses of the pieces delivered to the multiple-roll calender.

21. The method as in claim 19, wherein the gap between the rolls combined in pairs is set based on a number of layers forming the string of pieces stacked one on another.

22. The method as in claim 18, wherein a number of rolls is selected from the range of 4-40.

23. The method as in claim 19, wherein the maximum distance between the rolls pertaining to different pairs does not exceed the maximum dimensions of the pieces stacked in a continuous string and delivered to the multiple-roll calender.

24. The method as in claim 1, wherein the stages d] - g] are repeated several times.

25. The method as in claim 1, wherein the drying is fulfilled at the ambient pressure and a temperature of 20 - 300 °C.

26. The method as in claim 26, wherein the duration of the carbon strip drying is selected from the range of 1 - 10 hours.

27. The method as in claim 1, wherein drying is carried out at the low pressure.

28. The method as in claim 28, wherein pressure is selected from the range of 0.1 to 0.5 atm.

29. The method as in claim 28, wherein drying duration is selected from the range of 10-120 minutes.

30. The method as in claim 1, wherein the diameter of calender rolls is selected from the range of 90 to 1000 mm.

31. The method as in claim 1, wherein the temperature of the calender rolls is selected from the range of 20 - 100 °C.

32. The carbon electrode obtained by the method as in claims 1-31, consisting substantially of porous carbon material, containing conductive additive and polymer binder, which is characterized by a thickness of 1-3 mm, electric resistance uniformity along the carbon electrode surface not higher than 10%, density of carbon electrode in the range of 0.6 - 0.7 g/cm³, tensile strength not less than 0,1 MPa, specific electric capacitance in sulfuric electrolyte reaches 1300 - 1600 F/g, capacitance density in sulfuric acid electrolyte is equal to 750 - 900 F/cm³.

33. The electrode as in claim 32 in which a porous carbon material particle size lies the range of 0,5 - 10 microns.

34. The electrode as in claim 32 in which a porous carbon material is characterized by a specific surface area of 500 - 3000 m²/g-

35. The electrode as in claim 32 in which the content of a porous carbon material is selected from the range of 80 - 99%.

36. The electrode as in claim 32 in which the conductive additive is selected from carbon black, powdery graphite, carbon nanotubes, graphene nanosheets or their mixture can be used.

37. The electrode as in claim 32 in which the content of a conductive additive is selected from the range of 0 - 15%.

38. The electrode as in claim 32 in which substantially polytetrafluoroethylene (PTFE) is used as a binder.

39. The electrode as in claim 32 characterized by the factor that the content of polymer binder is selected from the range of 1-10%.

40. The electric energy storage device containing at least one carbon electrode according to claim 32, produced according to claim 1, together with current collector, at least one counter electrode, an electrolyte, a separator and as well the container wherein the indicated components are placed.

41. Vehicle using the electric energy storage device according to claim 40.

42. Stationary energy storage system using the electric energy storage device according to claim 40.