RU197738U1 - BATTERY DEVICE FOR MEMBRANE-ELECTRODE BLOCKS OF THE FLOWING BATTERY - Google Patents

Abstract

The claimed utility model of a battery of membrane-electrode blocks of a flowing battery relates to the field of renewable energy, namely, flowing redox batteries, which are a type of fuel cells, for storing, storing and reproducing electricity from renewable sources. This device is simple in design with a minimized value of shunt current, high resistance to chemically aggressive environments, thanks to the selected materials and the ability to work on various chemical reagents. device structures, Teflon plates with through holes, Teflon plates with engraved flow channels, Teflon plates for membranes and electrodes, slip rings with Viton rings, electrodes and proton exchange membranes in which flow fields for electrolytes are made out of contact with slip rings plates and are located inside two combined plates of fluoroplastic, allowing, thus, to work with highly chemically aggressive environments. The magnitude of the shunt currents is minimized by isolating the supply channels with electrolyte from the collector plates with Viton sealing rings. Current collector plates of each membrane-electrode block have ends that extend outward, which makes it possible to control the distribution of potential throughout the battery. 12 s.p. f-ly; 11il.

Description

Technical field

The claimed utility model relates to the field of renewable energy, namely to flow redox batteries, which are a type of fuel cell for storing, storing and reproducing electricity from renewable sources. This device is simple in design with a minimized value of the shunt current, high resistance to chemically aggressive environments, thanks to the selected materials and the ability to work on various chemical reagents.

The accumulation of electricity obtained by converting the energy of light, water and wind is one of the key provisions in the field of renewable energy and requires the use of special devices - flowing redox batteries, which differ from lithium-ion batteries in the principle of operation and device. These devices allow you to accumulate energy of a wide variety of volumes than they recommend themselves in a wide variety of applications. It is relevant to develop a universal design of a flow redox battery, the materials of which are highly resistant to aggressive environments. The claimed device has the ability to work on various chemically aggressive reagents.

State of the art

A well-known system of cells, membrane-electrode blocks (OIE), which together form a hybrid flow redox battery operating on metal (Fe ²⁺ / Fe ³⁺ ) redox pairs, with a plurality of flow-through electrolyte supplying the cell system through a whole structure placed in a certain way channels [US 9614244 B2, 2013]. The design of this device allows the use of plates of carbon material in the form of folded ribs as electrodes, which, in turn, may have perforation. A step-by-step system of flow channels for the electrolyte minimizes the magnitude of the shunt current. The disadvantage of such a hybrid flow redox battery is the large number of inlet and outlet openings on the end plates, which makes the structure cumbersome and increases the number of places where there is a high probability of leakage.

Known flowing metal-halogen battery [US 8137831 B1, 2011], the main functional parts of which are two half cells, each of which contains two electrodes and a reaction zone between them. This device is designed to work on metal-halogen redox pairs. This type of electrochemical system works as follows: the halogen component is reduced on a positively charged electrode, and the metal undergoes oxidation on a negatively charged electrode. An aqueous solution contributes to the replenishment of halogen particles at the surface of the electrode. One suitable system is a zinc-chlorine flow battery, where chlorine is used as halogen and zinc is used as metal. The disadvantage of this design is the narrow range of electrochemical systems that can be used, as well as a significant difference in the design of half cells, since with an increase in their number, which will increase battery power, there will inevitably appear inconsistencies between the functional units of each half cell during assembly.

A known design of a cell and a set of such cells forming a battery with a redox stream, as well as a method for producing it [WO 2017174053 A1, 2017]. This design has at least two frame elements of each cell, two electrodes and a membrane between them, duplicated as many times as necessary. Moreover, two frame elements of each half-cell are equipped with four channels, so that solutions of two electrolytes can flow along the internal parts of the half-cells without the possibility of mixing, since this structural element is hermetically sealed. The disadvantage of this design is the inability to check the potential difference between each cell, which is a functional unit of the entire battery with a redox stream, which can lead to an imbalance in the potential distribution and failure of the electrode material.

An urgent task is to create a battery of membrane-electrode blocks of a flowing battery with the ability to work on electrochemical systems of various nature (redox pairs), the minimum possible value of the shunt current, and also in conditions of their high chemical aggressiveness with the ability to control the distribution of potential relative to each OIE , which is part of the claimed utility model of the battery of membrane-electrode blocks of a flowing battery.

Closest to the claimed solution is a high-performance flowing redox battery with a supporting frame element and a monolithic bipolar plate built into the frame element. A bipolar plate contains many flow channels on each side of it. The frame element contains two feed channels on the one hand and two on the other hand, discharging the reacted electrolyte. The specifics of the distribution of the system of thinner serpentine-type channels extending from the supply and intake channels is that they are pairwise aligned opposite each other. This arrangement of the flow channels allows one to minimize ohmic losses and reduce the internal resistance of the entire battery as a whole, as well as thereby optimizing the use of the useful surface of bipolar plates made of graphite-modified vinyl ether. The frame element is made of fiberglass modified vinyl ester. The use of these materials as structural materials allows you to work on highly aggressive environments and in a significant temperature range without changing the nature of the electrochemical reagents used in electrolytes. The disadvantage of this device is the use of labor-intensive materials in processing, requiring special equipment, which entails a large amount of waste. In addition, the location of the channels, although it makes it possible to achieve sufficiently high discharge characteristics without destroying the materials of the electrodes and bipolar plates, but during prolonged operation will lead to leakage due to the close proximity to the edge of the plates in which they are held. The solidity of the battery does not leave it possible to monitor the distribution of potential relative to each cell in the battery, no matter how many there are. Even the proven prototype manufacturing technology and its testing under various conditions for a long time does not guarantee that the potential will be stationary, and this requirement is one of the key in running redox batteries.

Disclosure of Entity

The technical problem of the claimed utility model is the creation of a battery of membrane-electrode blocks of a flowing battery, the structural elements of which are able to work in contact with highly chemically aggressive media of various nature, as well as providing the ability to control the magnitude of the potential on each membrane-electrode block included in the battery.

The technical result achieved by the claimed utility model is the creation of a battery of membrane-electrode blocks of a flow accumulator, in which flow fields for electrolytes are made out of contact with current collector plates and are located inside two combined plates of fluoroplastic, thereby allowing working with highly chemically aggressive environments. The value of the shunt currents is minimized by isolating the supply channels with electrolyte from the collector plates with Viton sealing rings. Current collector plates of each membrane-electrode block have ends facing out with copper contacts, which allows you to control the potential distribution throughout the battery.

The technical result is achieved as follows. In total, the claimed utility model of the battery of the membrane-electrode blocks of the flowing battery contains 10 cells - 10 OIE. Input of the supply channels is carried out from two sides (one input and output channel on each side) in such a way that each OIE is powered by an electrolyte in parallel. Initially, Viton gaskets are located at both ends of the battery to improve the tightness of the entire structure, then Teflon plates with through holes for moving the input and output feed channels from where they are located on the end plates to the place of feeding the entire battery of membrane-electrode blocks, according to the developed designs. The impossibility of the initial location of the inlet and outlet openings on the end plates in the right place is due to the piling of the structure from the outside. The sinuous-shaped feed channels are made in Teflon plates 1 mm thick by engraving with a carbon dioxide laser. The material Teflon is selected as suitable from the point of view of resistance to highly chemically aggressive environments, which are most often used as electrolyte components and as malleable to processing. The channels are engraved in two plates with a depth of 0.8 mm with a mirror reflection relative to each other along the vertical axis, thereby, when superimposed on each other, forming a single plate, hidden inside, with a single flow channel for each of two electrolytes. The length and thickness of the channels were calculated in advance, and an optimal ratio of these values was proposed for implementation, which allows minimizing the value of shunt currents. The plates are fastened by applying a glue solution (10% p-p parafilm in chloroform ch.ch.) to the front side of each plate at a temperature of 180 ° C and a pressure of 20-50 kg for 5 minutes. Each such glued plate has 2 flow channels for one electrolyte and two for the other, pairwise falling into the electrode space through the through holes located at the ends of the flow channels in the center of the plate. Current collection (graphlex) plates are made of thermally expanded graphite (hereinafter referred to as graphlex), the manufacture of which was carried out by the same method as Teflon, but with an increased pressure during pressing up to 6000 kg. A copper contact with the tail was introduced into the graphlex plate, which, subsequently, was fastened to the contact of the next current collector graphlex plate, forming a bipolar single plate. The supply channels passing through the battery are isolated from bipolar graphlex plates by inserting o-rings from Viton, which also helps to reduce the shunt current to its minimum value and increases the service life of the flow battery. In the design, a membrane with a thickness of about 75 microns is used as a proton exchange membrane, and segraset is used as the electrode material. The execution of Teflon and graphlex current collection plates in a single form factor allows you to control the distribution of potential for each OIE of the proposed utility model of the battery of membrane-electrode blocks of a flowing battery.

Brief Description of the Drawings

The utility model is illustrated by drawings, where in FIG. 1 shows the main structural elements of the claimed utility model in their chronological sequence during assembly, and in FIG. 2 - the claimed utility model of the battery of the membrane-electrode blocks of the flowing battery in assembled form. FIG. 3-9 show in more detail a part of the structural elements, namely: a Viton gasket (6), a Teflon plate (7) and (8), Teflon plates (9) and (10) with flow channels applied by engraving, as well as Teflon plates (14) and (17) under the proton exchange membrane and electrodes.

FIG. 10 is a graph of the average voltage across the battery during charge / discharge versus time for a composition of 1 M V 4 M H2SO4. The feed rate of electrolytes is 100 ml / min. Current at charge / discharge 600 mA.

FIG. 11 is a graph depicting the Faraday, voltaic, and energy efficiency of a battery of memrane-electrode blocks of a flowing battery depending on the discharge / charge cycle for a composition of 1 M V 4 M H2SO4 in relative units. The feed rate of electrolytes is 100 ml / min. Current at charge / discharge 600 mA.

Utility Model Implementation

Below is a more detailed description of the claimed utility model of the battery of memrane-electrode blocks of a flowing battery, not limiting its essence, presented in an independent claim, but only demonstrating the possibility of realizing the purpose with achieving the claimed technical result.

The inventive utility model of the battery of memrane-electrode blocks of a flowing battery can work on most well-known electrochemical systems that make up the electrolyte, having a sufficiently high resistance to aggressive environments and the lowest possible value of shunt currents.

The proposed utility model consists of end plates (1) and (19) having eight through holes (21) into which bushings (4) and screws (3) are inserted with their threaded end up. Further, all structural elements have the same eight holes (21), with the help of which they are mounted alternately on eight screws (3). Compression fittings (5) are threaded outwards into the end plates into the holes (22), on which caps (2) are screwed onto the end of the assembly. The Viton gasket (6) has two elevations (34), with which, when tightening, an additional sealing of the supply channels at the inlet and outlet of the device, as well as two through holes (35), occurs. The Teflon plate (7) has through holes (23), and the plate (8) has through holes (24). On the plate (9) made of the same Teflon material, four channels are flowed through the engraving method (25), fed from the supply channels through the through hole (26). Also on the plate (9) there are two through holes (27) through which the electrolyte circulates in the electrode space. (28), is a through hole and closes with the same hole (27) on the plate (10) (when superimposed), completely repeating the Teflon plate (9), except that (27) and (28) change in places. The collector plate (12) is equipped with a copper contact (31) for closing with subsequent formation of a bipolar plate. (12) also has two through holes (30) and four through holes (29) into which Viton O-rings (13) are inserted. The collector plate (18) completely repeats the geometry and shape of the collector plate (12), except that the through holes (30) are shifted 90 degrees clockwise, as well as the copper contact (31) is on the opposite side. The Teflon plate (14) has a square recess for laying the proton exchange membrane, a depth of half its cross section, and also four through holes (32). In addition, an engraving of the flow channels (33) is applied to the Teflon plate (14), through which the electrolyte enters directly into the electrode space formed by the cavity (34). The Teflon plate (17) completely repeats (14), except that the engraved flow channels are rotated 90 degrees clockwise horizontally and 180 degrees vertically. Next, four electrodes (15) are inserted into the cavity (34). A proton exchange membrane (16) is placed on top. In FIG. 1 a large square bracket indicates the area corresponding to one OIE in the claimed battery. In the proposed design there are only ten such OIE repeating each other. After the last one is assembled, the Teflon plates (8) and (7) are reinserted onto the screws (3), then the Viton gasket (6) and the end plate (19), which differs from the end plate (1) with a through diameter, completes the assembly holes (21).

Depending on the type of electrolyte used, atmospheric conditions and various requirements for flow redox batteries and similar systems, it is possible to use end plate materials, electrodes, plates with engraved flow channels and gaskets with lower chemical resistance in order to reduce the cost of construction: for the end plate - duralumin instead of titanium, for plates with engraved flow channels - ebonite, coprolon, polypropylene, etc., for electrodes - graphite foil, carbon fabric, etc.

The design of the battery of the membrane-electrode blocks of the flowing battery may undergo various changes and modifications understood by one skilled in the art upon reading the present description. Such changes do not limit the scope of claims. For example, the overall dimensions of all structural elements can change, provided that the channels and holes located inside remain in their places, the diameter of the screws by means of which the entire structure is screed, their number, etc.

Before carrying out test measurements, the battery is assembled according to the circuit depicted in FIG. 1. In the assembled state, the structure is shown in FIG. 2. At the same time, the proton exchange membrane (16) is preliminarily kept in distilled water for 10 minutes. 8 bushings (4) are inserted into the end plate (1), and 8 bolts (3) are inserted into them. Then, the viton gasket (6), the Teflon plates (7) and (8) are alternately put on. The plates (9) and (10) have flowing engraved channels (25) opposite each other. The following structural elements comprise one OIE (highlighted by square brackets in Fig. 1): current collector plate (12), through which 4 Viton O-rings (13) are inserted through holes (29); a teflon plate (14) into which 4 electrodes (15) and a proton exchange membrane (16) are inserted; a teflon plate (17), into which 4 electrodes (15) are also inserted, a current collection plate (18) with four Viton O-rings inserted (13) and two Teflon plates (9) and (10) with flowing engraved channels located opposite each other (25). Repeating these steps 9 more times allows achieving the image in FIG. 2, which shows the battery of membrane-electrode blocks of the flowing battery in assembled form. Upon completion of the duplication of parts, the Teflon plates (8) and (7), as well as the Viton gasket (6), are put on again. The assembly ends with the end plate (19). The whole structure is clamped on top with nuts for the screws (3).

Before taking measurements, hoses made of polytetrafluoroethylene, as the most resistant to aggressive media material, are connected to the assembled battery using a cap (2) screwed onto a compression fitting (5). Connect the electrochemical equipment (potentiostat-galvanostat) to the end terminals of the battery.

To demonstrate the operation, a battery of mem- brane-electrode blocks of a flowing accumulator was manufactured and cyclic charge / discharge measurements of 50 cycles were performed on an electrolyte solution of 1 M p-p vanadyl sulfate in 4 M sulfuric acid.

The experiment was to test the battery performance at an average level of load on the device. The measurements were carried out in the galvanostatic mode with a superimposed current of 600 mA of alternating sign and boundary conditions for potentials of 16 V for the charged state of the battery and 8 V for discharged. These experimental conditions are fully consistent with the operating mode of flowing redox batteries.

In FIG. 10 is a graph describing the behavior of a battery of membrane-electrode blocks of a flowing battery in operating mode. Based on the data shown in FIG. 11, we can conclude that for 18000 seconds the device worked without any deterioration in its performance. Energy efficiency is in the range of 75-78%, voltaic - 65-75%, and Faraday 88-95%. The set of values shown in FIG. 10 and 11, illustrates the performance of the system close to the maximum possible.

Thus, tests of the battery of memrane-electrode blocks of a flowing accumulator showed that the value of shunt currents is minimized, since, otherwise, the combination of all efficiencies would be 20-30% lower in their values. The position of the graph in FIG. 10 proves battery performance in contact with highly chemically aggressive environments. The chemical effect of other redox pairs will be at the same or less high level, which means that the ability to work on electrochemical systems of various nature (redox pairs) is confirmed. The potential distribution between each membrane-electrode block included in the test battery was monitored. The difference between each of them ranges from 100-200 mV, which is the norm for energy storage systems of this type.

Claims (13)

1. The battery of membrane-electrode blocks of a flowing battery, consisting of end titanium plates, viton gaskets, creating an additional seal of the device structure, Teflon plates with through holes, Teflon plates with engraved flow channels, Teflon plates for the membrane and electrodes, collector plates with inserted through holes with Viton sealing rings, electrodes and proton exchange membranes, characterized in that the Viton gaskets have protrusions at the through holes, which creates an additional seal and seals the area of the electrolyte duct, plates for the membrane and electrodes have a groove for electrodes and flow channels of a smaller section than in plates with engraved flow channels, which leads to an increased pressure drop and a uniform flow of electrolyte in the electrode space, using the entire surface of the electrode material. 2. The battery according to claim 1, characterized in that the plates with engraved flow channels are made of highly chemically inert materials. 3. The battery according to claim 1, characterized in that the membrane plates and electrodes are made of highly chemically inert materials. 4. The battery according to claim 1, characterized in that all the structural elements are made in a square single form factor with holes for the screed removed from the main field. 5. The battery according to claim 1, characterized in that the collector plates are made of thermally expanded graphite and have protruding copper contacts designed to create a bipolar plate, and allowing to control the potential distribution on each membrane-electrode block. 6. The battery according to claim 1, characterized in that the through holes in the collector plates are isolated from the supply channel by Viton O-rings. 7. The battery according to claim 1, characterized in that the Teflon plates with engraved flow channels are hermetically attached to each other with a 10% paraphilic solution in chloroform chemically pure 8. The battery under item 1, characterized in that the Teflon plates under the membrane and electrodes are hermetically attached to each other with a 10% solution of paraphilic in chloroform reagent grade 9. The battery according to claim 1, characterized in that the design assumes how much a suitable increase in its power by duplicating the composition of the parts making up a single membrane-electrode block. 10. The battery under item 1, characterized in that the selected length of the flow channels determines the minimum value of the shunt currents. 11. The battery under item 1, characterized in that the thickness of the collector plates is 0.8 mm 12. The battery under item 1, characterized in that the thickness of the Teflon plates with engraved flow channels is 1 mm. 13. The battery according to claim 1, characterized in that the thickness of the Teflon plates for the membrane and electrodes is 1 mm.

Images