Bipolar plate electrode arrangement using thermoplastic resin and method for its manufacture

Abstract

Bipolar plate electrode arrangement used in a redox flow battery stack, comprising a bipolar plate (140) made of a thermoplastic resin, Electrodes (170A, 170B) are arranged on opposite sides of the bipolar plate (140), wherein the electrodes (170A, 170B) are thermally compressed at a central section of the bipolar plate (140) so that they penetrate the bipolar plate (140), and Fiber mats (150A, 150B), wherein a size of the bipolar plate (140) is larger than a size of the electrodes (170A, 170B), the bipolar plate (140) has a periphery (141) which is outside the electrodes (170A, 170B), the fiber mats (150A, 150B) are hot-pressed so that they penetrate into the periphery (141) of the bipolar plate (140), and the intruded fiber mats (150A, 150B) have a shape that has an inner opening, and the outer size of the fiber mats (150A, 150B) is equal to the outer size of the bipolar plate (140) and the size of the inner opening is smaller than the outer size of the electrodes (170A, 170B).

Description

BACKGROUND OF THE INVENTION Area of ​​the invention

[0001] The present invention relates to a bipolar plate electrode arrangement used for a unit cell for a redox flow battery, and in particular to a bipolar plate electrode arrangement in which a thermoplastic resin is used, and to a method for its manufacture. Description of the state of the art

[0002] A redox flow battery is one of the key products closely linked to renewable energy, greenhouse gas reduction, rechargeable batteries, and smart grids, all of which have received considerable attention worldwide in recent years. Fuel cell batteries are increasingly gaining market share as a renewable energy source that replaces fossil fuels without emitting pollutants. Currently, most energy is derived from fossil fuels, but the use of such fuels causes severe environmental damage, including air pollution, acid rain, and global warming, and their energy efficiency is low.

[0003] To solve the problems caused by the use of such fossil fuels, interest in renewable energies and fuel cells has increased rapidly in recent years. Interest in and research into such renewable energies are being actively pursued, not only domestically but worldwide.

[0004] Although the renewable energy market has matured both domestically and internationally, the problem remains that the amount of energy generated is subject to significant fluctuations due to environmental factors such as time and weather, depending on the type of renewable energy source. Therefore, the widespread adoption of energy storage systems (ESS) for storing recovered energy, which is used to stabilize renewable energy generation, is urgently needed, and the redox flow battery is gaining attention as a high-capacity energy storage system of this kind.

[0005] An overall structure of the redox flow battery, which is the subject of the present invention, consists of a stack 1 with stacked cells in which an electrochemical reaction takes place, a container 3 for storing an electrolyte, and a pump 4 for supplying an electrolyte from the electrolyte container to the stack.

[0006] Fig. Figure 2 shows a simplified structure of the stack 1, which is the subject of the present invention, and shows an end plate 11, an insulating plate 12, a current plate 13, a bipolar plate 14, a seal 15, a flow frame 16, an electrode 17, a seal 15, an ion exchange membrane 18, a seal 15, an electrode 17, a flow frame 16, a seal 15, a bipolar plate 14, a current plate 13, an insulating plate 12, and an end plate 11 from the left side. A unit cell is formed from the bipolar plate 14 to the bipolar plate 14, and a stack is built up by stacking between several dozen and several hundred unit cells.

[0007] The present invention relates to the manufacture of an arrangement for the integration of a bipolar plate 14 and electrodes 17 arranged on both sides of the bipolar plate 14, and US patent 6656639 B1 exists for this purpose.

[0008] While in US 6656639 B1 the arrangement is produced by inserting an electrode and a resin film (material for a bipolar plate) into a stencil and thermally compressing it, the resin film is heated in a section that is not in contact with the electrode, and at the boundary between a section that is not in contact with the electrode and a section that is in contact with the electrode, a residual stress is generated during a cooling process, and this leads to the problem that the bipolar plate is deformed or its thickness is reduced when it is separated from the stencil.

[0009] US Patent 2004 / 0202915 A1 teaches a cell frame for a redox flow battery comprising a bipolar plate made of conductive plastic and a frame attached around a periphery of the bipolar plate. The frame comprises at least 50% by mass vinyl chloride, and the bipolar plate consists of conductive plastic comprising 10-80% by mass graphite and 10-60% by mass of a chlorinated organic compound. SUMMARY OF THE INVENTION

[0010] The object of the present invention is to produce a bipolar plate-electrode arrangement, and in particular an integrated bipolar plate-electrode arrangement, which can solve problems such as the deformation of the bipolar plate-electrode arrangement or the reduction of strength during cooling after thermal compression of a thermoplastic resin film as a bipolar plate material between electrodes.

[0011] Another objective of the present invention is to increase the strength by penetrating a fiber mat into a section where the strength of the thermoplastic resin film may be reduced during the thermal compression process of the electrode and the thermoplastic resin film.

[0012] According to one aspect of the present invention, a bipolar plate-electrode arrangement for use in a redox flow battery stack is provided, comprising a bipolar plate made of a thermoplastic resin, electrodes arranged on opposite sides of the bipolar plate, wherein the electrodes are thermally compressed at a central section of the bipolar plate so that they penetrate the bipolar plate, and fiber mats, wherein a size of the bipolar plate is larger than a size of the electrodes; the bipolar plate has a periphery that is outside the electrodes, the fiber mats are heat-pressed so that they penetrate the periphery of the bipolar plate, and the penetrated fiber mats have a shape having an inner opening, and the outer size of the fiber mats is equal to the outer size of the bipolar plate and the size of the inner opening is smaller than the outer size of the electrodes.

[0013] Part of the fiber mats can be positioned between the periphery of the electrode and the bipolar plate and hot-pressed to penetrate the bipolar plate.

[0014] According to a further aspect of the present invention, a method for producing a bipolar plate-electrode assembly is provided, comprising: arranging a fiber mat having an inner opening on each of the two sides of a thermoplastic resin film as the material of a bipolar plate; arranging an electrode material on a central section of each of the two sides of the thermoplastic resin film; arranging templates on the fiber mats; and hot-pressing the outer surfaces of the templates and the electrode material, wherein the outer size of the fiber mats is equal to the outer size of the bipolar plate and the size of the inner opening is smaller than the outer size of the electrodes.

[0015] The order of arranging the electrode material and the stencil can be interchangeable.

[0016] The template can have a shape that features an inner opening, the outer size of the template can be equal to the outer size of the fiber mats, and the size of the inner opening can be equal to the outer size of the electrode material.

[0017] A flow path can be formed via the electrodes.

[0018] A fiber mat penetrates a thermoplastic resin film of a bipolar plate material that is not in contact with the electrode in the embedded bonding body of the bipolar

[0019] The electrode stands to reduce warping and deformation and increase strength, thereby producing a high-quality bonding body of the bipolar electrode.

[0020] Furthermore, the fiber mat is reinforced on the inside of the electrode's edge, thus preventing tearing at the electrode's periphery.

[0021] Furthermore, the stacking frame is bonded and firmly attached, thus preventing performance degradation due to electrolyte leakage at the stacking frame.

[0022] Furthermore, it provides stable protection against corrosion or breakage during long-term use, as the resin film does not deteriorate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above-mentioned and other aspects, features and other advantages of the present invention will become clearer from the following detailed description, which is to be understood in conjunction with the accompanying drawings, in which: Fig. 1 a schematic view of a redox flow battery which is the subject of the present invention; Fig. 2 a perspective exploded view of a redox flow battery stack according to the prior art; Fig. 3 shows a structural element for the production of a bipolar plate-electrode arrangement according to the invention; Fig. 4-6 show a method for producing a bipolar plate electrode arrangement of the present invention; Fig. 7 is a perspective view of a bipolar plate electrode arrangement according to the invention; Fig. Figure 8 shows a further embodiment of a bipolar plate electrode arrangement according to the invention; Fig. 9 a manufacturing process of the embodiment of Fig. 8 shows; and Fig. 10 another manufacturing process of the embodiment of Fig. 8 shows. DETAILED DESCRIPTION OF THE PREFERRED EXECUTION FORM

[0024] The present invention will now be described in more detail with reference to the accompanying drawings.

[0025] The accompanying drawings represent exemplary embodiments of the present invention and serve to explain the present invention in detail. However, the technical scope of protection of the present invention is not limited to these.

[0026] The present invention describes a method for producing a bipolar plate-electrode arrangement. The electrode is a location through which the electrolyte passes and where an electrochemical reaction occurs, and a porous conductive material is used, with graphite felt 170 being preferred. In a unit cell, an anode electrode 170A and a cathode electrode 170B are inserted sequentially. (However, a flow path can be formed in the anode electrode and the cathode electrode, as shown in...) Fig. (6 shown.)

[0027] The bipolar plate 140 is a component that separates the unit cells, completely blocks the electrolyte, and allows only one flow of electricity. In the present invention, a thermoplastic resin film is used as the bipolar plate. The thermoplastic resin itself is non-conductive. However, during thermocompression, the electrode penetrates the resin, and during this process, the resin becomes conductive.

[0028] Fig. Figure 3 shows components for manufacturing the arrangement of electrode 170 and the bipolar plate of Fig. 7 as an embodiment of the present invention.

[0029] A fiber mat 150 is preferably made of an electrically conductive material such as a thin film (material similar to a nonwoven fabric) made of a fibrous material (carbon fiber, glass fiber or similar) or carbon felt of very low thickness, but is not limited to this.

[0030] However, in order for the fiber mat 150 to be used on the redox flow battery, it is necessary to use an acid-resistant material, and the outer size of the fiber mat 150 must be equal to the outer size of the thermoplastic resin film as the material of the bipolar plate 140, and the inner opening must be smaller than the outer size of the electrode 170.

[0031] A mounting template 160 compresses the fiber mat and the bipolar plate 140, which is the thermoplastic resin film, in a hot pressing process, so that the fiber penetrates the bipolar plate, and the thickness of the mounting template 160 is less than that of the electrode 170. The outer size of the mounting template is equal to the outer size of the bipolar plate 140, and the inner opening is equal to the outer size of the electrode 170.

[0032] Fig. 4 shows a state in which the in Fig. The three listed components are stacked between heating plates 200A and 200B. Fiber mats 150A and 150B are arranged at both peripheries of the bipolar plate 140. The outer size of the fiber mat 150 is equal to the outer size of the thermoplastic resin film, which is the material of the bipolar plate 140, so that the fiber mat and the bipolar plate can be aligned parallel to each other.

[0033] Subsequently, the electrodes 170A and 170B are arranged on both central sections of the bipolar plate 140, and since the outer sizes of the electrodes 170A and 170B are larger than the inner openings of the fiber mats 150A and 150B, an overlapping section like a circle A is created.

[0034] The stencils 160A and 160B are then positioned on the fiber mats 150A and 150B. The outer dimensions of the stencils are equal to the outer dimensions of the bipolar plate 140, and the inner opening is equal to the outer dimensions of the electrodes 170A and 170B, so that the stencils 160A and 160B are positioned only on the fiber mats 150A and 150B. When hot pressing is subsequently carried out with the heating plates 200A and 200B positioned on both sides, a pressing situation is created as shown in Fig. 5 shown.

[0035] Additionally, the order in which electrodes 170A and 170B and templates 160A and 160B are arranged can be changed.

[0036] When hot pressing is performed, the fiber mats 150A and 150B, arranged on both sides of the bipolar plate 140, and the electrodes 170A and 170B penetrate the bipolar plate to be integrated into it, forming the bipolar plate-electrode arrangement as shown in Fig. 6 and Fig. 7 is shown, it is formed.

[0037] Only the fiber mats 150A and 150B penetrate the periphery 141 of the bipolar plate 140, and the electrodes 170A and 170B penetrate the center of the bipolar plate. The fiber mat and the electrode penetrate the bipolar plate simultaneously at the inner section of the electrode periphery.

[0038] According to the invention, the fiber mat 150 is applied to the periphery 141 of the bipolar plate 140 without the electrode 170 to increase the strength, and the electrode 170 and the fiber mat 150 partially overlap to prevent a weakening of the periphery of the electrode 170 or the fiber mat 150.

[0039] The fiber mat 150 penetrates completely into the bipolar plate 140 in the form of the resin film through the compression process, so that a smooth surface is formed at the periphery 141, and the smooth surface 141 can be attached to the adjacent flow frame 16.

[0040] Fig. Figure 8 shows a further embodiment of the present invention in which a flow path 142 is formed through the electrode 170 on the bipolar plate 140. This allows the electrolyte to pass between two or more rectangular felt electrodes to reduce the pressure drop of the electrolyte, thereby improving system efficiency.

[0041] The electrode / bipolar plate arrangement of Fig. 8 can form a flow path at a central section of electrode 170 in the electrode / bipolar plate arrangement, which is in Fig. 6 is produced using a machining tool or engraving tool, as in Fig. 9 shown. The bipolar plate felt connected to the electrode has penetrated an inserted section (141), and the inserted section has a sufficiently high thickness.

[0042] The in Fig. The electrode / bipolar plate arrangement shown in Figure 8 can be formed as follows: Arranging a fiber mat 150' having two or more internal openings on both sides of the bipolar plate 140, as shown in Figure 8. Fig. Figure 10 shows the arrangement of two or more electrodes 170', and the subsequent arrangement and hot pressing of a template 160' having two or more internal openings.

[0043] Additionally, the order of arranging the electrode 170' and the template 160' can be changed.

[0044] The electrode material can be graphite felt, carbon felt, carbon paper, carbon cloth or similar.

[0045] The thermoplastic resin film that forms the material of the bipolar plate 140 can use polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polycarbonate (PC), polyethylene terephthalate resin (PET), polyethylene terephthalate (PETG), polymethyl methacrylate (PMMA) and acrylonitrile butadiene styrene (ABS) films.

Claims

[1] Bipolar plate electrode arrangement used in a redox flow battery stack, comprising a bipolar plate (140) made of a thermoplastic resin, Electrodes (170A, 170B) are arranged on opposite sides of the bipolar plate (140), wherein the electrodes (170A, 170B) are thermally compressed at a central section of the bipolar plate (140) so that they penetrate the bipolar plate (140), and Fiber mats (150A, 150B), wherein a size of the bipolar plate (140) is larger than a size of the electrodes (170A, 170B), the bipolar plate (140) has a periphery (141) which is outside the electrodes (170A, 170B), the fiber mats (150A, 150B) are hot-pressed so that they penetrate into the periphery (141) of the bipolar plate (140), and the intruded fiber mats (150A, 150B) have a shape that has an inner opening, and the outer size of the fiber mats (150A, 150B) is equal to the outer size of the bipolar plate (140) and the size of the inner opening is smaller than the outer size of the electrodes (170A, 170B). [2] Bipolar plate electrode arrangement according to claim 1, wherein a portion of the fiber mats (150A, 150B) is arranged between the periphery of the electrode (170A, 170B) and the bipolar plate (140) and is hot-pressed to penetrate the bipolar plate (140). [3] Bipolar plate electrode arrangement according to claim 1, wherein a flow path (142) is formed over the electrodes (170A, 170B). [4] Bipolar plate electrode arrangement according to claim 2, wherein a flow path (142) is formed over the electrodes (170A, 170B). [5] Method for manufacturing a bipolar plate electrode arrangement, comprising: Arranging a fiber mat (150A, 150B) having an inner opening on each of both sides of a thermoplastic resin film as material of a bipolar plate (140); Arranging an electrode material on a central section of each of the two sides of the thermoplastic resin film; Arranging stencils (160A, 160B) on the fiber mats (150A, 150B); and Hot pressing of the outer surfaces of the stencils (160A, 160B) and the electrode material, where the outer size of the fiber mats (150A, 150B) is equal to the outer size of the bipolar plate (140) and the size of the inner opening is smaller than the outer size of the electrodes (170A, 170B). [6] Manufacturing method according to claim 5, wherein the sequence of arranging the electrode material and the arranging the template is interchangeable. [7] Manufacturing method according to claim 6, wherein the template (160A, 160B) has a shape having an inner opening, the outer size of the template (160A, 160B) is equal to the outer size of the fiber mats (150A, 150B) and the size of the inner opening is equal to the outer size of the electrode material. [8] Manufacturing process according to claim 5, further comprising: Forming a flow path (142) on the electrode material with a machining tool or an engraving bit after hot pressing. [9] Manufacturing process according to claim 6, further comprising: Forming a flow path (142) on the electrode material with a machining tool or an engraving bit after hot pressing. [10] Manufacturing process according to claim 5, further comprising: Forming a flow path (142) on the electrode material with a machining tool or an engraving bit after hot pressing. [11] Manufacturing process according to claim 6, further comprising: Forming a flow path (142) on the electrode material with a machining tool or an engraving bit after hot pressing. [12] Manufacturing method according to claim 5, wherein each of the fiber mats (150A, 150B) has two or more internal openings, two or more electrode materials are arranged, the template (160A, 160B) has two or more internal openings, and a flow path (142) is formed which crosses the electrode material. [13] Manufacturing method according to claim 6, wherein each of the fiber mats (150A, 150B) has two or more internal openings, two or more electrode materials are arranged, the template (160A, 160B) has two or more internal openings, and a flow path (142) that crosses the electrode material is formed.

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