CN220796810U - Separator for flow battery stack and single battery - Google Patents

Abstract

The application provides a membrane and a single cell for a flow battery stack. The membrane comprises a frame and an ion exchange membrane, wherein the frame comprises a non-reaction area and a first transition area, the non-reaction area is surrounded around the first transition area, the ion exchange membrane comprises a reaction area and a second transition area, the second transition area is surrounded around the reaction area, the first transition area and the second transition area are overlapped, and the material of the frame is a corrosion-resistant insulating material. The diaphragm is adopted to insulate the non-reaction area in the frame without ion exchange, thereby reducing self-discharge of the galvanic pile and greatly improving the mechanical strength of the non-reaction area.

Description

Separator for flow battery stack and single battery

Technical Field

The application relates generally to the field of flow batteries, and more particularly to a membrane and a single cell for a flow battery stack.

Background

The flow battery is a novel large-scale energy storage battery, and is one of the main stream means for solving the problem of intermittent instability of novel energy sources such as wind energy, solar energy and the like due to the advantages of high safety, long service life, large electric storage capacity, separation and adjustability of power and capacity and the like.

The electric pile is a core component of the flow battery, and a single electric pile mainly comprises key components such as an ion exchange membrane, an electrode, a bipolar plate and the like, wherein the ion exchange membrane is one of key materials of the flow battery, and the performance of the ion exchange membrane directly influences the performance and the service life of the flow battery. Because the flow battery is generally applied to a large-scale long-term energy storage system, the volume of a galvanic pile is large, the compression force and the shearing force required by the assembly and the sealing of the galvanic pile are large, and the non-reaction area of the ion exchange membrane is at risk of damage under the action of the compression force and the shearing force for a long time. In practical use, there is a small amount of ion exchange on both sides of the non-reaction zone of the ion exchange membrane, which can cause the precipitated crystals in the zone to abrade the ion exchange membrane.

On the other hand, in order to reduce concentration polarization of the flow battery, the flow battery pile usually adopts a short-flow (with a larger length-width ratio value) structural design, so that the utilization rate of the ion exchange membrane is greatly reduced. Therefore, aiming at the technical problems, how to improve the mechanical strength and the insulativity of the ion exchange membrane in the non-reaction area and reduce the material ratio of the ion exchange membrane in the non-reaction area is a technical problem to be solved in the field.

Disclosure of Invention

The technical problem to be solved by the application is to provide a diaphragm and a single cell for improving the mechanical strength and the insulativity of a non-reaction area of an ion exchange membrane and improving the utilization rate of the ion exchange membrane.

In order to solve the technical problem, the application provides a diaphragm for a flow battery pile, which comprises a frame and an ion exchange membrane, wherein the frame comprises a non-reaction area and a first transition area, the non-reaction area is enclosed around the first transition area, the ion exchange membrane comprises a reaction area and a second transition area, the second transition area is enclosed around the reaction area, the first transition area is overlapped with the second transition area, and the material of the frame is a corrosion-resistant insulating material.

In an embodiment of the present application, the material of the frame includes any one or a combination of a plurality of polypropylene, polyethylene and polytetrafluoroethylene.

In an embodiment of the present application, a first transition area of at least one surface of the frame is coated with an adhesive, and the first transition area and the second transition area are bonded by the adhesive.

In an embodiment of the present application, the non-reactive area of at least one surface of the bezel is also coated with the adhesive.

In one embodiment of the present application, the adhesive is a fluorine-containing adhesive.

In one embodiment of the present application, the adhesive comprises any one or a combination of a fluorine-containing polyacrylate adhesive, a fluorine-containing epoxy resin adhesive, and a fluorine-containing polyolefin adhesive.

In an embodiment of the present application, the thickness of the adhesive in the first transition region is smaller than the thickness of the adhesive in the non-reactive region.

In one embodiment of the present application, the thickness of the adhesive in the first transition region is 5 to 50 μm, and the thickness of the adhesive in the non-reaction region is 30 to 75 μm.

In an embodiment of the present application, the widths of the first transition region and the second transition region are the same, and are both 5mm to 30mm.

In one embodiment of the present application, the thickness of the non-reactive region is 0.1mm to 1mm.

In an embodiment of the present application, the frame further includes a plurality of positioning structures, and the plurality of positioning structures are disposed in the non-reaction area.

In an embodiment of the present application, the frame further includes a plurality of common flow holes, and the common flow holes are disposed in the non-reaction region.

The application also provides a single cell for a flow battery pile for solving the technical problem, which comprises the diaphragm, wherein electrodes, electrode frames and bipolar plates are respectively arranged on two sides of the diaphragm in sequence.

The membrane and the single cell for the flow battery stack are provided for solving the problems that the mechanical strength of the flow battery ion exchange membrane in a non-reaction area is poor and the service life of the flow battery ion exchange membrane is short due to poor insulativity, and a frame is arranged for the ion exchange membrane. Meanwhile, the diaphragm of the application remarkably improves the utilization rate of the ion exchange membrane, reduces the cost of the ion exchange membrane of the flow battery, and can be welded or bonded and sealed with the electrode frame through the frame material, so that the use of traditional sealing rubber at the side of the galvanic pile membrane is reduced, and the maintenance cost is reduced. The diaphragm frame of this application has certain hardness, still further has solved the flow battery field because ion exchange membrane material is soft and be difficult to realize automated production's problem.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the accompanying drawings:

FIG. 1 is a schematic structural view of a membrane for a flow battery stack according to an embodiment of the present application;

fig. 2 is a schematic structural view of a flow battery stack according to an embodiment of the present application.

Detailed Description

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are used in the description of the embodiments will be briefly described below. It is apparent that the drawings in the following description are only some examples or embodiments of the present application, and it is obvious to those skilled in the art that the present application may be applied to other similar situations according to the drawings without inventive effort. Unless otherwise apparent from the context of the language or otherwise specified, like reference numerals in the figures refer to like structures or operations.

As used herein, the terms "a," "an," "the," and/or "the" are not specific to the singular, but may include the plural, unless the context clearly dictates otherwise. In general, the terms "comprises" and "comprising" merely indicate that the steps and elements are explicitly identified, and they do not constitute an exclusive list, as other steps or elements may be included in a method or apparatus.

The relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present application unless it is specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective parts shown in the drawings are not drawn in actual scale for convenience of description. Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but should be considered part of the specification where appropriate. In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.

In addition, the terms "first", "second", etc. are used to define the components, and are merely for convenience of distinguishing the corresponding components, and unless otherwise stated, the terms have no special meaning, and thus should not be construed as limiting the scope of the present application. Furthermore, although terms used in the present application are selected from publicly known and commonly used terms, some terms mentioned in the specification of the present application may be selected by the applicant at his or her discretion, the detailed meanings of which are described in relevant parts of the description herein. Furthermore, it is required that the present application be understood, not simply by the actual terms used but by the meaning of each term lying within.

Flowcharts are used in this application to describe the operations performed by systems according to embodiments of the present application. It should be understood that the preceding or following operations are not necessarily performed in order precisely. Rather, the various steps may be processed in reverse order or simultaneously. At the same time, other operations are added to or removed from these processes.

The membrane and the single cell for the flow battery stack can be applied to flow batteries, including but not limited to all-vanadium flow batteries, iron-based flow batteries, zinc-based flow batteries, lead-acid flow batteries and the like, and are particularly suitable for all-vanadium flow batteries.

Fig. 1 is a schematic structural view of a membrane for a flow battery stack according to an embodiment of the present application. Referring to fig. 1, the membrane 100 of this embodiment includes a frame 110 and an ion exchange membrane 120, where the frame 110 includes a non-reaction region 111 and a first transition region 112, the non-reaction region 111 is enclosed around the first transition region 112, the ion exchange membrane 120 includes a reaction region 121 and a second transition region 122, the second transition region 122 is enclosed around the reaction region 121, the first transition region 112 and the second transition region 122 overlap, and the material of the frame 110 is a corrosion-resistant insulating material.

Specifically, referring to fig. 1, the separator 100 is generally rectangular in shape as a whole, with a longer length in the X direction and a shorter width in the axial direction, wherein the Y direction is the flow direction of the electrolyte, thus forming a structure with a larger aspect ratio value as shown in fig. 1, which is advantageous in reducing concentration polarization of the flow battery. The present application uses the X direction as the length direction and the Y direction as the width direction.

Ion exchange membranes 120 in the separator of the present application include, but are not limited to, perfluorosulfonic acid membranes.

As shown in fig. 1, the shape of the frame 110 is substantially rectangular, and it is a frame structure, that is, the interior of the frame has a hollow structure, and the area of the hollow structure corresponds to the reaction area 121. The length of the reaction zone 121 is denoted by c and the width of the reaction zone 121 is denoted by d. The first transition region 112 in the frame 110 is a rectangular annular region surrounding the periphery of the reaction region 121, which is indicated by hatching in fig. 1, and has widths S1, S2 in the X-direction and the Y-direction, respectively. In some embodiments s1=s2, in other embodiments s1+notes2. In some embodiments, S1 and S2 are both in the range of 5mm to 30mm.

The non-reactive region 111 is enclosed around, i.e. peripherally around, the first transition region 112. The non-reaction region 111 and the first transition region 112 are virtually integral, i.e., the bezel 110 is divided into the non-reaction region 111 and the first transition region 112. As shown in fig. 1, assuming that the separator 100 has a length a and a width b, the non-reaction region 111 includes four regions disposed above and below and around the first transition region 112, wherein the regions disposed above and below the first transition region 112 are wider and have a width of about: (b-d-2 s 2)/2, the regions to the left and right of the first transition region 112 being narrower and having a width of about: (a-c-2 s 1)/2. (a-c-2 s 1)/2 is less than (b-d-2 s 2)/2.

As shown in fig. 1, the ion exchange membrane 120 has a rectangular shape, and has a length of c+2×s1 and a width of d+2×s2. The desired dimensions may be obtained by clipping. The second transition region 122 coincides with the first transition region 112 and appears as the same shaded portion in fig. 1.

In a conventional flow battery stack, the separator is an entire ion exchange membrane, sandwiched between electrode frames on both sides, and sealed and connected by sealing rubber. The area of the ion exchange membrane covered by the electrode frame is a non-reaction area, and the part exposed in the hollow area of the electrode frame is a reaction area. During operation of the stack, the ion exchange membrane and the electrode frame are subjected to corresponding pressures due to the fastening pressure of the stack, and the phenomenon that electrolyte enters the non-reaction zone may occur. After the electrolyte enters the non-reaction zone, the electrolyte is not easy to flow in the non-reaction zone, and a dead zone is formed. In the charge and discharge process, electrochemical reaction in the dead zone is continuously carried out, and crystal precipitation occurs, so that the ion exchange membrane is punctured and damaged.

The membrane 100 of the present application differs in structure from conventional ion exchange membranes. The diaphragm 100 adopts a corrosion-resistant insulating material as a material of the frame, and the non-reaction area is arranged on the frame, so that the non-reaction area has certain strength, corrosion resistance and insulativity. The frame 110 and the ion exchange membrane 120 can be firmly coupled to each other by providing the first transition region 112 and the second transition region 122 to collectively form a transition region between the reaction region 121 and the non-reaction region 111.

The specific material of the frame 110 is not limited in this application, and in particular, the corrosion-resistant insulating material may include any one or a combination of a plurality of polypropylene, polyethylene, and polytetrafluoroethylene.

It will be appreciated that the bezel 110 has a thickness and has two opposing surfaces. In some embodiments, the first transition region 112 of at least one surface of the bezel 110 is coated with an adhesive, and the first transition region 112 and the second transition region 122 are bonded by the coated adhesive.

In some embodiments, the thickness of the border 110 of the non-reactive region 111 is 0.1mm to 1mm.

In some embodiments, the ion exchange membrane 120 is bonded to a surface of the frame 110 via a second transition region 122. At this time, the thickness of one frame 110 is 0.1mm to 1mm. In these embodiments, the non-reactive region 111 of the bezel 110 is not coated with adhesive, but is coated with adhesive only in the first transition region 112.

In other embodiments, the ion exchange membrane 120 is bonded between two opposing rims 110. In these embodiments, the two opposing sides of the two rims 110 are coated with an adhesive. Specifically, when the membrane 100 is prepared, two identical frames 110 may be first prepared, non-reaction regions and first transition regions on opposite surfaces of the two frames 110 are coated with an adhesive, and then the ion exchange membrane 120 is sandwiched between the two frames 110, so that the two non-reaction regions of the two frames 110 are bonded to each other, and the two first transition regions are located on two sides of the second transition region and bonded to the second transition region. According to this embodiment, the ion exchange membrane 120 is protected by double-sided lamination. Meanwhile, in these embodiments, adhesive is applied only to two opposite sides of the bezel 110, and adhesive is not applied to the other two opposite sides. At this time, the thicknesses of the two frames 110 are 0.1mm to 1mm in total.

In some embodiments, the adhesive is a fluorine-containing adhesive. More specifically, the adhesive includes any one or a combination of a plurality of fluorine-containing polyacrylate adhesives, fluorine-containing epoxy resin adhesives, and fluorine-containing polyolefin adhesives.

In some embodiments, the thickness of the adhesive in the first transition region 112 is made smaller than the thickness of the adhesive in the non-reaction region 111 when the adhesive is applied, so that after the ion exchange membrane 120 is bonded, the thickness of the membrane 100 as a whole tends to be uniform, and there is no significant height difference on the surface of the membrane 100, since the ion exchange membrane 120 also has a certain thickness.

In some embodiments, the thickness of the diaphragm 100 is uniform. The thickness of the adhesive of the first transition region 112 plus the thickness of the ion exchange membrane 120 is equal to the thickness of the adhesive of the non-reactive region 111.

Specifically, the thickness of the adhesive in the first transition region 112 is 5 to 50 μm, and the thickness of the adhesive in the non-reaction region 111 is 30 to 75 μm.

In some embodiments, the membrane 100 of the present application further includes a plurality of positioning structures 130 on the rim 110. As shown in fig. 1, the positioning structures 130 in this embodiment are positioning holes, and the frame 110 includes four positioning holes, which are located on two long sides of the frame 110. Meanwhile, each long side is also provided with a bulge 131, and the positioning hole is positioned at the bulge 131. The purpose of these positioning structures 130 is for alignment of each cell in the stack, including alignment of electrode frames, separator membranes, bipolar plates, etc. in each cell, when the stack is assembled.

In some embodiments, the frame 110 of the diaphragm 100 of the present application has a plurality of common flow holes 140 disposed in the non-reaction region 111. As shown in fig. 1, four common flow passage holes 140 are provided at four corners of the diaphragm 100, respectively, and two of them are located at one long side of the non-reaction region 111 and the other two are located at the other long side of the non-reaction region 111.

The present inventors have compared the membrane 100 of the present application with a conventional ion exchange membrane by experiments, and specific experiments and results are as follows.

Example 1

The material of the frame is selected from PP (polypropylene) materials with the thickness of 0.2mm, wherein the length of a non-reaction area is a=650 mm, the width b=350 mm, the length of a reaction area is c=580 mm, the width d=250 mm, and the width of a transition area is s1=s2=10 mm. And (5) carrying out mechanical strength test on the non-reaction area material and calculating the utilization rate of the ion exchange membrane. The ion exchange membrane utilization was calculated from the ratio of the area of the reaction zone to the total area of the ion exchange membrane.

Example 2

The material of the frame is PE (polyethylene) material with the thickness of 0.5mm, the length of the non-reaction area a=1150 mm, the width b=500 mm, the length of the reaction area c=1100 mm, the width d=340 mm, and the width S1=S2=15 mm. And (5) testing the mechanical strength of the material in the non-reaction area and calculating the utilization rate of the ion exchange membrane.

Comparative example 1

The membrane adopts a whole perfluorosulfonic acid membrane, and has the length of 650mm and the width of 350mm. In the comparative example, the whole perfluorosulfonic acid membrane seat ion exchange membrane is adopted, and the frame is not included, so that the utilization rate of the ion exchange membrane is equal to the area of the reaction area/the area of the perfluorosulfonic acid membrane.

Comparative example 2

The diaphragm adopts a whole perfluorosulfonic acid film, and has the length of 1150mm and the width of 500mm.

Performance tests and comparisons were made for examples 1 and 2 of the present application with comparative examples 1 and 2, respectively, and the test results are shown in table 1 below.

TABLE 1

The tensile strength of the non-reaction area is measured by a tensile test instrument, the insulativity of the non-reaction area is obtained by material characteristics, and the utilization rate of the ion exchange membrane is obtained by calculation. The length a and width b of the non-reactive region of example 1 are equal to those of the perfluorosulfonic acid membrane of comparative example 1, indicating that the profile dimensions of the two membranes are equal, and the tensile strength of the non-reactive region of comparative example 1, i.e., the perfluorosulfonic acid membrane. From the test results, the tensile strength and the ion exchange membrane utilization of example 1 are significantly higher than those of comparative example 1, and the non-reactive region of example 1 also has insulating properties. Similarly, example 2 also has similar results as compared to comparative example 2. According to the test results of the examples and the comparative examples, the separator 100 of the present application has remarkable improvement effect of mechanical strength and insulation in the non-reaction region, and the improvement of the utilization rate of the ion exchange membrane is remarkable.

The diaphragm 100 of the present application utilizes a corrosion-resistant insulating border material to replace the original non-reactive area of the ion exchange membrane, so that the area is insulated and free of ion exchange, the self-discharge of the galvanic pile is reduced, and the mechanical strength of the area is greatly improved. Meanwhile, the frame material is used for replacing the ion exchange membrane in the non-reaction area, so that the utilization rate of the ion exchange membrane is remarkably improved, the cost of the ion exchange membrane of the flow battery is reduced, the diaphragm 100 can be welded or bonded and sealed with the electrode frame through the frame material, the use of traditional sealing rubber on the membrane side of the galvanic pile is reduced, and the maintenance cost is reduced. The diaphragm frame of the application has certain hardness, and the problem that the automatic production is difficult to realize due to the fact that the ion exchange membrane material is soft in the field of flow batteries is further solved.

Fig. 2 is a schematic structural view of a flow battery stack according to an embodiment of the present application, in which the structure of one unit cell 202 in the stack 201 is shown in the form of an exploded view, the unit cell 202 including a separator 210, and electrodes 220, an electrode frame 230, and a bipolar plate 240, which are disposed on both sides of the separator 210, respectively, in sequence. A plurality of unit cells 202 are stacked to form a main structure of the stack 201. Diaphragm 210 may be welded or adhesively sealed to electrode frame 230 by its frame material, reducing the use of conventional sealing rubber on the galvanic film side and reducing maintenance costs.

In order to prepare the separator 100 described above, the present application also proposes a method for preparing a separator for a flow battery stack. The preparation method is used to form the separator 100 shown in fig. 1, and thus the foregoing description of the separator 100 can be equally applied to the description of the preparation method. It should be noted that fig. 1 is not intended to limit the specific shape and size of the separator 100. The diaphragms formed based on the ideas of the present application are all within the scope of the claimed application. Referring to fig. 1, the preparation method comprises the following steps:

step S310: the frame material is pre-cut to form a frame 110, a hollowed-out area is arranged in the frame 110, the hollowed-out area corresponds to a reaction area 121 of the ion exchange membrane 120 of the membrane 100, the frame 110 comprises a non-reaction area 111 and a first transition area 112, and the non-reaction area 111 is surrounded on the periphery of the first transition area 112.

Step S320: an adhesive is applied to the first transition region 112 of at least one surface of the frame 110, and the applied adhesive is thermally cured.

Step S330: the ion exchange membrane 120 is cut, and the ion exchange membrane 120 includes a reaction region 121 and a second transition region 122, and the second transition region 122 is enclosed around the reaction region 121.

Step S340: attaching the ion exchange membrane 120 to the frame 110, and overlapping the first transition region 112 and the second transition region 122;

step S350: performing hot pressing treatment on the frame 110 and the ion exchange membrane 120;

step S360: and carrying out cold press curing shaping treatment on the frame 110 and the ion exchange membrane 120 after the hot pressing treatment.

The foregoing description of the materials, dimensions, and the like, involved in the separator 100 may be used in the above-described preparation method.

In some embodiments, in step S320, adhesive is applied only to the first transition region 112 of one surface of one frame, and the ion exchange membrane 120 is attached to the frame in step S340.

In other embodiments, in step S320, adhesive is applied to the opposing surfaces of the two rims while the non-reaction region 111 and the first transition region 112, and the ion exchange membrane 120 is disposed between the two rims in step S340.

In step S320, the purpose of the heat curing process is to cause the adhesive to be heat cured. In some embodiments, the heat curing treatment is performed at a treatment temperature of 80 to 100 ℃ for a treatment period of 5 to 300 seconds. Specifically, the frame material coated with the adhesive can be put into an oven for drying and heat preservation, so that the adhesive is solidified and attached to the surface of the frame.

In step S330, the ion exchange membrane 120 is trimmed, which may be in accordance with the dimensional requirements for the reaction zone 121 and the second transition zone 122 described above.

In step S350, the sandwich structure including the frame-ion exchange membrane-frame is aligned and abutted by the positioning structure before the hot pressing process. The heat pressing treatment is to compact and adhere the three-layer structure. In some embodiments, the autoclave is operated at a temperature of 120 to 150℃and a pressure of 1 to 2.5MPa for a period of 30 to 60 seconds.

In step S360, if naturally cooled after the hot pressing process, deformation of some materials may be caused, thereby deforming the entire diaphragm 100 by warping, wrinkling, or the like. Such deformation can be avoided by cold-press curing and shaping, and the surface of the diaphragm 100 can be flattened. In some embodiments, the pressure of the cold press solidification shaping treatment is 5-10 Mpa, and the treatment duration is 90-300 s.

In some embodiments, in step S310, further comprising: a plurality of positioning structures 130 are formed in the non-reaction region 111. As shown in fig. 1, to form the positioning structure 130, when the frame material is pre-cut, the outline of the frame 110 may be formed according to the design, including cutting out the protruding portion 131, and forming a positioning hole by digging a hole in the protruding portion 131. These alignment holes may also be used for alignment of the two rims 110 in step S350.

In some embodiments, after step S360, further comprising: the frame 110 and the ion exchange membrane 120 after the cold press curing and shaping treatment are cut to meet the requirement of the outline size of the diaphragm 100, and the common flow passage holes 140 are formed on the frame 110. In combination with the foregoing steps S310 to S360, it can be understood that the frame 110 and the ion exchange membrane 120 are cut 2 times. By the second cutting, the misalignment error due to the bonding, deformation, etc. in the above steps can be eliminated, so that the shape and size of the finally formed diaphragm 100 can achieve a predetermined effect.

While the basic concepts have been described above, it will be apparent to those skilled in the art that the foregoing application disclosure is by way of example only and is not intended to be limiting. Although not explicitly described herein, various modifications, improvements, and adaptations of the present application may occur to one skilled in the art. Such modifications, improvements, and modifications are intended to be suggested within this application, and are therefore within the spirit and scope of the exemplary embodiments of this application.

Meanwhile, the present application uses specific words to describe embodiments of the present application. Reference to "one embodiment," "an embodiment," and/or "some embodiments" means that a particular feature, structure, or characteristic is associated with at least one embodiment of the present application. Thus, it should be emphasized and should be appreciated that two or more references to "an embodiment" or "one embodiment" or "an alternative embodiment" in various positions in this specification are not necessarily referring to the same embodiment. Furthermore, certain features, structures, or characteristics of one or more embodiments of the present application may be combined as suitable.

Likewise, it should be noted that in order to simplify the presentation disclosed herein and thereby aid in understanding one or more inventive embodiments, various features are sometimes grouped together in a single embodiment, figure, or description thereof. However, this method of disclosure does not imply that more features than are previously mentioned are required for the subject of the present application. Indeed, less than all of the features of a single embodiment disclosed above.

In some embodiments, numbers describing the components, number of attributes are used, it being understood that such numbers being used in the description of embodiments are modified in some examples by the modifier "about," approximately, "or" substantially. Unless otherwise indicated, "about," "approximately," or "substantially" indicate that the number allows for a 20% variation. Accordingly, in some embodiments, the numerical parameters employed in this application are approximations that may vary depending upon the desired properties sought for the individual embodiment. In some embodiments, the numerical parameters should take into account the specified significant digits and employ a method for preserving the general number of digits. Although the numerical ranges and parameters set forth herein are approximations that may be employed in some embodiments to confirm the breadth of the range, in particular embodiments, the setting of such numerical values is as precise as possible.

Claims (10)

1. The membrane for the flow battery pile is characterized by comprising a frame and an ion exchange membrane, wherein the frame comprises a non-reaction area and a first transition area, the non-reaction area is surrounded around the first transition area, the ion exchange membrane comprises a reaction area and a second transition area, the second transition area is surrounded around the reaction area, the first transition area and the second transition area are overlapped, and the frame is made of a corrosion-resistant insulating material.

2. The membrane of claim 1, wherein the material of the frame comprises any one or a combination of polypropylene, polyethylene, polytetrafluoroethylene.

3. The diaphragm of claim 1, wherein a first transition region of at least one surface of the frame is coated with an adhesive, the first transition region and the second transition region being bonded by the adhesive.

4. A diaphragm according to claim 3, wherein the non-reactive areas of at least one surface of the frame are also coated with the adhesive.

5. The separator according to claim 3 or 4, wherein the adhesive comprises any one of a fluorine-containing polyacrylate adhesive, a fluorine-containing epoxy resin adhesive, and a fluorine-containing polyolefin adhesive.

6. The separator of claim 4, wherein the thickness of the adhesive in the first transition region is less than the thickness of the adhesive in the non-reactive region, and the thickness of the non-reactive region is between 0.1mm and 1mm.

7. The separator of claim 6, wherein the adhesive has a thickness of 5 to 50 μm in the first transition region and a thickness of 30 to 75 μm in the non-reactive region.

8. The separator of claim 1, wherein the first transition region and the second transition region are the same width, both being 5mm to 30mm.

9. The diaphragm of claim 1 wherein said frame further comprises a plurality of locating structures and a plurality of common flow holes, said plurality of locating structures and said plurality of common flow holes being disposed in said non-reaction region.

10. A single cell for a flow battery stack, comprising a separator according to any one of claims 1-9, wherein electrodes, electrode frames and bipolar plates are provided in sequence on both sides of the separator, respectively.